United States
Environmental Protection
Agency
February 1981
Region 10
1200 6th Avenue
Seattle, WA 98101
EPA-10-ID-Boise/Eagle-Ada-WWTW-81
Environmental Draft
Impact Statement
Wastewater Management for
Boise, Eagle, and Ada County,
Idaho
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U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION X
1200 SIXTH AVENUE
SEATTLE, WASHINGTON 98101
REPLY TO ..._ .._
ATTN OF: M/S 443
TO ALL INTERESTED AGENCIES, PUBLIC GROUPS AND CITIZENS:
We are forwarding for your review and comment this-Draft Environmental
Impact Statement (DEIS) for Wastewater Management for Boise, Eagle
and Ada County, Idaho.
The Environmental Protection Agency (EPA) is preparing this EIS
pursuant to Section 102(2)(c) of the National Environmental Policy
Act of 1969 and implementing Agency regulations. We have prepared the
EIS to serve as an informational document on the potential impacts of
construction of wastewater treatment facilities for the Cities of Boise
and Eagle. Discussions of alternative solutions that have been con-
sidered during the planning process are included, as well as measures
that may be taken to minimize the environmental impacts.
Availability of the EIS will be announced in the Federal Register on
Friday, March 27, 1981, beginning a 45-day comment period. When you
have reviewed the DEIS, if you have any comments on it or wish to provide
additional information for inclusion in the final EIS, we would appreci-
ate hearing from you before the close of the comment period on May 11,
1981. All comments received will be given consideration in evaluating
the alternatives before EPA's decision is made on the proposed project.
Comments or questions concerning this Draft EIS should be submitted to
the attention of Ms. Norma Young (M/S 443) at the above address. Copies
of the EIS are available for review at EPA's Idaho Operations Office in
Boise, in the Seattle Regional Office and in the Boise and Eagle public
libraries.
A technical Appendix has been prepared to accompany this DEIS. General
distribution has not been made of the Appendix; however, copies are
available for review in the offices and libraries named above. If you
have a pressing need for\a personal copy of the Appendix, please send
your request to M's. Young in the Seattle Regional Office.
A public hearing will be held to discuss the Draft EIS at 7:30 p.m.
on April 30, 1981 in the Les Bois Room on the third floor of Boise City
Hall. We invite you to attend the hearing. All are welcome and will
have an opportunity to be heard.
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Draft
Environmental Impact Statement
Wastewater Management for
Boise, Eagle and Ada County, Idaho
Prepared by:
U. S. Environmental Protection Agency
Region 10
Seattle, Washington 98101
With technical assistance from:
Jones & Stokes Associates, Inc.
2321 P Street
Sacramento, California 95816
Responsible
JOTS
Regional Administrator
F£B 1 2 198.1
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TABLE OF CONTENTS
EXECUTIVE SUMMARY i
Purpose and Need for Action i
Project Alternatives iii
Background iii
No Action v
Alternatives Available to EPA v
Other Alternatives Considered vi
City and Facilities Plan Recommendations vi
Description of Alternatives vii
Impacts of the Proposed Alternatives xiv
Summary Comparison of Alternatives xiv
CHAPTER 1 - INTRODUCTION 1
The EIS Process 1
Grant Programs Under the Clean Water Act 1
Background to Development of This EIS 2
Report Format 2
CHAPTER 2 - COORDINATION 5
Introduction 5
Coordination Efforts to Date 5
Continuing Coordination Efforts 7
CHAPTER 3 - WATER QUALITY MANAGEMENT IN ADA COUNTY 9
Locational Setting 9
Existing Wastewater Treatment Facilities 9
City of Boise Facilities 9
Eagle Water and Sewer District 15
Southwest Community Wastewater Management Study 15
Facility Problems 15
Gowen Field Treatment Plant 18
Lander Street Treatment Plant 18
West Boise Treatment Plant 18
Eagle Water and Sewer District Facilities 18
Southwest Community Area 18
CHAPTER 4 - WASTEWATER TREATMENT ALTERNATIVES 21
Introduction 21
City of Boise Facilities 21
Discharge Requirements 21
Staging and Capacity Considerations 22
Development of Project Alternatives 30
Energy Requirements 41
Project Costs 43
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Eagle Water and Sewer Facilities 43
Flow and Waste Load Projections 50
Treatment Alternatives 50
Interceptor Systems 52
Energy Requirements 53
Project Costs 53
Southwest Community 58
Operation and Maintenance Program Alternatives 58
Costs 59
Best Management Plan 59
CHAPTER 5 - ANALYSIS OF FACILITY PLANNING POPULATION
PROJECTIONS 63
Introduction 63
EPA Policy on Population Projections for Facilities
Planning 63
EPA Approved Population Projections for Facilities
Planning in Ada County 63
Description of Facility Planning Population
Projections 64
Boise Planning Area 64
Southwest Planning Area 64
Eagle Planning Area 64
Growth Accommodated by Facility Plans 66
Introduction 66
Boise Facility Planning 66
Eagle Facility Planning 67
Indirect Impacts of Growth 67
Summary 67
CHAPTER 6 - LAND USE CONDITIONS AND TRENDS 69
Introduction 69
Land Use Planning Framework 69
Study Area Characteristics 70
Wastewater Facility Planning Areas 70
Existing Land Use 73
Land Use Plans and Policies 75
Boise Planning Area 75
Southwest Planning Area 78
Eagle Planning Area 79
Future Land Use 79
Boise Planning Area 81
Southwest Planning Area 84
Summary 86
CHAPTER 7 - AIR QUALITY 87
Introduction 87
Terminology 87
Meterological Factors 88
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Existing Air Quality Problems 91
Summary 92
ESL/CH2M Hill Study 93
EPA Study 93
Idaho Air Quality Bureau Study 93
Permanent Monitoring Station Data 96
Idaho Transportation Department Monitoring Data 98
Air Quality Management Considerations 103
Institutional Framework 103
Emissions Inventories and Forecasts 106
Future Air Pollution Potential in Ada County 114
State Implementation Plan Consistency 128
CHAPTER 8 - GROUNDWATER RESOURCES 131
Geology 131
Regional Geology 131
Geology of Study Area 131
Groundwater Hydrology 135
Boise Valley Aquifers 135
Groundwater Occurrence and Flow 136
Groundwater Quality 137
"Nonpoint Source Waste Loadings of the Groundwater 142
Summary of Existing Nonpoint Source Discharges
to Groundwater in Ada County 142
Impact of On-Site Wastewater Disposal Systems on
Groundwater Resources 144
Groundwater Conditions and Land Use Change 145
Mitigation Measures 146
Impacts of Sludge Disposal on Groundwater Resources 147
Boise Sludge Disposal Site 147
Mitigation Measures 148
Eagle Water and Sewer District Disposal Site 149
CHAPTER 9 - HYDROLOGY AND SURFACE WATER QUALITY 151
Existing Conditions 151
Hydrology 151
Water Quality 158
Impact Analysis 166
Hydrologic Changes 166
Water Quality Changes 166
Construction Impacts 169
Mitigation Measures 169
Summary of Impacts 170
CHAPTER 10 - FISHERY RESOURCES 171
Existing Habitat Conditions and Species Productivity 171
Boise River 171
Impacts of Flow Augmentation and Discharge
Routing Alternatives 182
Direct Impacts on Fisheries 187
Indirect Impacts on Fisheries 187
Summary of Impacts 188
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CHAPTER 11 - VEGETATION AND WILDLIFE 189
Environmental Setting 189
Vegetation and Wildlife Habitats 189
Wildlife 191
Impact Analysis 200
Direct Impacts ^03
Indirect Impacts ^
9 n R
Impact Summary ^UJ
Potential Mitigation Measures 205
CHAPTER 12 - AGRICULTURAL LANDS IN ADA COUNTY 207
Introduction 207
Agricultural Resources in Ada County 207
Trends in Agricultural Use 208
Agricultural Lands Conversion Process 208
An Overview of Agricultural Land Conversion
Process 208
Existing Measures for Retention of Agricultural
Lands in Ada County 213
Impact - Conversion of Agricultural Land to Urban
Uses Through Provision of Wastewater Treatment 216
Boise Planning Area 216
Southwest Planning Area 217
Eagle Planning Area 218
Summary of Impacts 218
Potential Measures Available to Mitigate
the Loss of Agricultural Lands 219
CHAPTER 13 - PUBLIC SERVICES AND FACILITIES 221
Drainage 221
Impacts 221
Mitigation Measures 222
Community Services 222
Water Supply 222
Gas and Electricity 224
Solid Waste Management 224
Schools 225
Police Protection 225
Fire Protection 226
Recreation 226
Mitigation Measures 227
Fiscal Overview 227
Introduction 227
Ada County 228
City of Boise 228
City of Eagle 229
Southwest Area 229
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CHAPTER 14 - ARCHEOLOGICAL AND CULTURAL RESOURCES 231
Introduction 231
Impacts 231
CHAPTER 15 - SUMMARY OF SIGNIFICANT PROJECT-RELATED
IMPACTS 235
Direct Wastewater Treatment and Disposal Impacts 235
Boise River 235
Growth Impacts 236
Air Quality 236
Conversion of Agricultural Land to Urban Uses 237
Public Services and Facilities 238
Vegetation, Wildlife and Fisheries 239
Drainage 239
Resources and Energy Use 240
Traffic Congestion 240
Water Resources 240
Construction-Related Impacts 241
Noise, Dust and Erosion 242
Traffic Disruption 244
Vegetation and Wildlife 244
Fisheries 246
Archeological and Cultural Resources 247
Disruption of Effluent Flow 248
Resources and Materials 248
No-Action Alternative 248
Boise 248
Eagle 249
LIST OF REPORT PREPARERS 251
ACRONYMS AND ABBREVIATIONS 255
EIS DISTRIBUTION LIST 257
BIBLIOGRAPHY 259
Reference Documents 259
Personal Communications 267
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LIST OF TABLES
Table Page
1 Impacts (Lander Street, West Boise and Eagle
Treatment Plants) xv
2 No-Action Alternatives xix
4-1 Boise Treatment Plant Effluent Limitations
Future and Historical 25
4-2 Sewage Generation Rates Used for the Boise Area 26
4-3 Existing and Projected Sewage Flows from Sewer
Service Areas in Boise 27
4-4 Population Projections for Sewer Service Areas
Served by the Lander Street and West Boise
Treatment Plant 28
4-5 Projected Commercial and Industrial Acreage
in Boise Area 29
4-6 Projected Waste Load from Sewer Service Areas
in Boise 31
4-7 Cost Analysis - West Boise Sludge Treatment 33
4-8 Sludge Management Alternatives 36
4-9 Capital Costs of Alternative Plans - North
Boise Interceptor 40
4-10 Ammonia Limitations 42
4-11 Process Energy Consumption for West Boise
Alternatives 44
4-12 Energy Consumption for Sludge Transportation
Alternatives 45
4-13 Recommended Alternative Cost Estimate Summary -
Stage One Expansion 46
4-14 Recommended Alternative Cost Estimate Summary -
Stage Two Expansion 47
4-15 User Impacts 48
4-16 Flow and Waste Load Projections - Eagle 51
4-17 Primary Energy Consumption 54
4-18 Present Worth and Annual Operation and
Maintenance Costs of Projected Alternatives
Eagle Water and Sewer District 55
4-19 Cost Summary - Eagle 57
4-20 Monetary Costs Analysis of On-Site Management
Program Alternatives - Southwest Area 60
5-1 Summary of DED Planning Area Population
Projections 65
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Table Page
6-1 1975 Vacant Land by Zoning Categories in
Boise Metropolitan Area 74
6-2 Land Use in Eagle's Area of City Impact in 1977 76
6-3 Target Holding Capacities for Boise Planning
Subareas 77
6-4 Allocation of Population and Land by Population
Planning, Subareas for the Boise Planning Area 82
7-1 Summary of Carbon Monoxide Emission Forecasts
for Northern Ada County 109
7-2 Carbon Mnoxide Emission Densities in Northern
Ada County 112
7-3 Community Planning Area - Characteristics
Reflected in the Emission Inventories and
Forecasts 118
7-4 Forecasts of Air Pollution Potential 121
7-5 Reductions from Projected CPA Emissions Required
to Indicate Attainment of 8-Hour CO Standard 122
7-6 Base Year (1977) Air Quality Values Used for
Rollback Analyses 126
8-1 Chemical Analyses of Deep and Shallow Ground-
water, Boise River Water and Agricultural
Drainage Waters in Boise Valley, Idaho 139
8-2 Summary of Estimated Nitrogen and Total Salt
Loadings to Groundwater from Irrigated
Croplands, Animal Husbandry and On-Site
Waste Disposal in Ada County, 1980 143
8-3 Summary of Estimated Nitrogen and Salt Loadings
to Groundwater Resulting from Irrigated
Agriculture, On-Site Waste Disposal and
Animal Husbandry in the Southwest Study
Area, 1980 143
9-1 Principal Reservoirs in the Boise River Basin 153
9-2 Lucky Peak Reservoir Storage Allocation 154
9-3 Protected Beneficial Uses of Waters of the
Boise River Basin below Lucky Peak Dam 160
9-4 Summary of Idaho State Water Quality Standards
for Designated Beneficial Uses 161
9-5 Average Water Quality Conditions of the Boise
River Main Stem 163
9-6 Average Water Quality Data Above and Below
Lander Street and West Boise Sewage Treatment
Plant Outfalls, October 1975-April 1980 165
9-7 Projected Fall and Winter Low Flow Conditions
in the Boise River 167
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Table Page
10-1 Fishes of the Boise River Between Lucky
Peak Dam and the River Mouth 173
10-2 Recommended Low Flow Regime in cfs for the
Boise River from Lucky Peak Dam to Snake
River 178
10-3 River Operation Mode Descriptions 184
10-4 Available Flows for River Operations Modes 185
11-1 Vegetation - Candidate Threatened or Endangered
Plant Species 192
11-2 Terrestrial Wildlife - Endangered and Threatened
Species and Species of Special Concern 196
12-1 Soils Capability for Agriculture 210
12-2 Farms, Land in Farms, and Land Use in Ada
County 1974 and 1969 211
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LIST OF FIGURES
Figure Page
1 Regional Setting iv
2 Existing Sewer Service Areas viii
3 Facility Planning Areas for the Eagle Water
and Sewer District ix
4 North Boise Interceptor Alternatives x
5 Alternative South Boise Interceptor Routes xi
6 Sludge Pipeline Routing and Land Application
Site xii
3-1 Regional Setting 10
3-2 Sewer Service Areas in the Boise Metropolitan
Area 11
3-3 Lander Street Treatment Plant Site Plan 13
3-4 West Boise Treatment Plant Site Plan 14
3-5 Eagle Water and Sewer District Facilities 16
3-6 Southwest Community Wastewater Management Study
Area 17
4-1 Existing Sewer Service Areas 23
4-2 Proposed Sewer Service Area 24
4-3 Sludge Pipeline Routing and Land Application
Site 35
4-4 North Boise Interceptor Alternatives 38
4-5 Alternative South Boise Interceptor Routes 39
4-6 Eagle Water and Sewer District Study Area 49
6-1 Incorporated Areas, Urban Service Planning
Areas and "Areas of City Impact" in Northern
Ada County 71
6-2 Boise Population Planning Areas and Subareas 72
6-3 Southwest Sketch Plan 80
7-1 Relationship Between Atmospheric Stability and
Inversion Conditions 90
7-2 Monitoring Sites Used in the ESL/CH2M Hill
Study 94
7-3 Monitoring Sites Used During the EPA Carbon
Monoxide Study 95
7-4 Monitoring Sites Used During the Idaho Air
Quality Bureau CO Study 97
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Figure Page
7-5 Average Winter Carbon Monoxide Levels at
the Boise Odd Fellows Hall Monitoring Site 99
7-6 Average Winter Carbon Monoxide Levels at the
Central District Health Department Monitoring
Station 100
7-7 Time Periods with 8-Hour CO Levels >9.0 ppm
at the Boise Odd Fellows Hall Monitoring
Station 101
7-8 Time Periods with 8-Hour CO Levels >9.0 ppm
at Central District Health Department
Monitoring Station 102
7-9 Community Planning Areas Outside the Boise
Metropolitan Area 107
7-10 Community Planning Areas in the Metropolitan
Boise Area 108
7-11 1980 Emission Source Density Index Values (daily
basis) for the Boise Metropolitan Area 115
7-12 1987 Emission Source Density Index Values (daily
basis) for the Boise Metropolitan Area 116
7-13 2000 Emission Source Density Index Values (daily
basis) for the Boise Metropolitan Area 117
7-14 Emission Reductions Needed to Achieve the
8-Hour CO Standard in 1987 124
7-15 Emission Reductions Needed to Achieve the
8-Hour CO Standard in 2000 125
8-1 Generalized Geologic Cross Sections of Boise
Valley 132
8-2 Generalized Geologic Map of the Boise-Nampa
Area 133
9-1 Boise River Watershed 152
9-2 Average Monthly Flow at Four Locations on
Boise River 156
9-3 Hydrologic Characteristics of the Boise River
Below Lucky Peak Dam and at Boise 157
10-1 Surface Waters 172
10-2 Percentage Composition for Total Fish, Game
Fish, and Nongame Fish in Electrofishing
Sample from the Boise River 11 July to
2 August 1974 174
10-3 Distribution of 13 Fish Species in the Boise
River from Barber Dam Downstream to the Mouth
as Determined by Electrofishing During
January-February, July-August and October 1974 176
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Figure Page
10-4 Comparison of Trout and White Fish Life
History, Stream Flow, in the Boise River
and'Recommended Maintenance Flows 179
11-1 Species of Special Concern Habitat 194
11-2 Deer and Elk Habitat 194
11-3 Waterfowl Habitat 201
11-4 Quail and Grouse Habitat 201
11-5 Partridge Habitat 202
11-6 Pheasant and Dove Habitat 202
12-1 Soil Capability for Agriculture in Ada County 209
12-2 Program for the Preservation of Agricultural
Land in Ada County 215
15-1 Noise from Construction Equipment 243
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EXECUTIVE SUMMARY
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EXECUTIVE SUMMARY
(x) Draft Environmental Impact Statement
( ) Final Environmental Impact Statement
Type of Action: Administrative
Purpose and Need for Action
In Ada County, Idaho, the City of Boise and the Eagle
Water and Sewer District (EWSD)* have initiated wastewater
treatment facility planning programs under the Clean Water
Grant program.
The Ada Planning Association (APA) has also requested
grant funds to evaluate wastewater management alternatives
in the rural portions of Ada County, particularly in the
ayrea Southwest of Boise.
The U. S. Environmental Protection Agency (EPA) has
awarded the City of Boise and the EWSD, Step I 201 funds
to develop facilities .plans for needed improvements in waste-
water treatment. The 208 funds were granted to APA for an
areawide study of wastewater management.
The intent of the Boise wastewater facilities planning
.was to develop a management plan to serve the Boise Metro-
politan Area through the year 2000. This plan includes a
means of improving water quality in the Boise River, and
for serving an expanding population base.
The City of Boise is currently served by three waste-
water treatment plants: Lander Street, West Boise, and Gowen
Field.
The Lander Street plant is currently operating at capacity,
both hydraulically and organically. The plant is not de-
signed to remove ammonia.
West Boise treatment plant is currently overloaded hydrau-
lically during the summer months due to high amounts of infil-
tration/inflow (I/I). Its organic load is far below capacity.
It is designed to remove ammonia throughout the year.
* A list of abbreviations and acronyms is found on page 255.
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The Gowen Field plant is underloaded both hydraulically
and organically. Effluent quality is generally good throughout
the year.
The operation of three dams located on the Boise River
above the City of Boise results in large flows in the Boise
River during the summer irrigation season and low flows during
the winter months. During the winter flow, conditions in
the Lander Street wastewater treatment plant may need modi-
fications to meet proposed water quality standards because
of ammonia concentrations in the effluent.
In order to meet water quality standards the Lander
Street plant will require construction of ammonia removal
facilities, and minimum instream flows in the Boise River
will be needed during the winter months, or both.
The Lander Street and West Boise wastewater treatment
plants need to be expanded, and the capacity of the Gowen
Field plant needs to be reevaluated.
The existing EWSD wastewater treatment facility is
operating at a 790 dwelling unit limit. Treatment facilities
must be upgraded to improve the quality of current discharge
and to allow further development options in the Eagle area.
Before additional Section 201 funds for design (Step 2)
and construction (Step 3) of a selected project can be awarded,
EPA must complete an environmental review of potential impacts
of the proposed projects to meet the requirements of the
National Environmental Policy Act (NEPA). EPA has prepared
this Environmental Impact Statement (EIS) to provide the
required review.
In the Boise preliminary draft facilities plan prepared
by CH2M Hill, it was assumed that the unincorporated South-
west Community would be served by the West Boise treatment
plant. However, during the development of the Southwest
Community wastewater management study by APA, a decision
was made not to provide sewers to this area.
Data from the Boise facility plan have been adjusted
in the DEIS to reflect that decision.
11
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Project Alternatives
Background
Ada County, Idaho is located north of the Snake River in
the southwestern part of the state (Figure 1). Encompassing
673,000 acres, most of the county is between 2,500 and 3,300
feet elevation. The northeastern portion of the county in-
cludes the slopes of the Boise Front, which rises to elevations
of about 5,900 feet. The southern part of the county is
primarily desert, with urban and agricultural areas concen-
trated in the northern half of the county. The northern
half of the county is drained by the Boise River, which joins
the Snake River along the border between Idaho and Oregon.
The City of Boise straddles the Boise River, with the
northern portions of the city against the lower slopes of
the Boise Front. The southern part of the city occupies
a series of river terraces (benches) rising south of the
Boise River. The City of Eagle is also located along the
Boise River, about 9 miles northwest (downstream) from down-
town Boise. The City of Meridian is located about 9 miles
due west of downtown Boise, while the small Town of Kuna
is 13 miles southwest of Boise. The Cities of Nampa and
Caldwell in neighboring Canyon County are about 18 and 24
miles west of Boise.
Boise is experiencing a rapid population increase. The
sewered population is expected to double in the next 20 years
to over 230,000 people. This rapid growth is placing a heavy
burden upon local public services, including schools, recre-
ation, fire and police protection, and drainage.
The present wastewater treatment facilities at Landers
Street and West Boise are essentially at capacity and effluent
discharges occasionally violate water quality standards.
On-site waste disposal is used in parts of Boise and
the surrounding area, and this is a threat to groundwater
quality. Existing facilities will not be able to handle
new population growth in the area without violation of National
Pollutant Discharge Elimination System (NPDES) standards.
The City of Eagle and vicinity is served by wastewater
treatment facilities managed by the EWSD. These facilities
are not able to meet new NPDES standards. New population
growth within the area is expected to more than double by
2000 and will require additional waste treatment facilities
in order to avoid continuing violation of waste discharge
criteria.
111
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-LEGEND-
•'iiini BOISE VALLEY BOUNDARY
ADAPTED FROM NACE.1903
BASE MAP'USGS 1:260,000 "BOISE",
REVISED 1976
FIGURE 1. REGIONAL SETTING
IV
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The APA has conducted a Southwest Community wastewater
management plan financed under Section 208 of the federal
Clean Water Grant which has culminated in adoption of a rural
lifestyle land use plan which limits growth in that area.
New growth, therefore, is expected to occur in other
areas of the county including those areas sewered by Boise
and by Eagle. This growth must be anticipated and the required
services, including wastewater treatment, must be provided
by the districts in which growth will occur.
No Action
Federal regulation (40 CFR, Part 6) requires that all
EISs consider the impacts of continued use of the wastewater
treatment and disposal methods currently serving area residents.
This is the no-action alternative.
For Boise this would mean that the existing Lander Street
and West Boise plants would continue to operate as is, with
the potential for ammonia toxicity, residual chlorine toxicity
and reduced oxygen levels during low river flows. There
is no capacity to handle additional population growth in
the area. Most of the Boise area residents using septic
tanks would continue to do so with potential surface and
groundwater contamination. The city would be unable to extend
central wastewater service to new residential, commercial
or industrial development.
For the EWSD the no-action alternative would mean con-
tinuing violation of the District's NPDES discharge permit
and would not provide for any improvement in the quality
of effluent being discharged into the Boise River. New
development would have to rely on the use of septic tanks.
Alternatives Available to EPA
EPA's principal roles in this project are to provide
an environmental review and to administer design and con-
struction funds available through Section 201 of the Clean
Water Act. EPA has a number of options available in acting
on the grant applicants' (City of Boise and EWSD) request
for federal funding of the wastewater project. In terms
of the structural configuration of treatment and disposal
processes, EPA could offer funds for a combination of pro-
cesses not currently included in a single alternative in
v
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the facilities plan. Although this is unlikely, it could
be done for environmental or economic reasons. In terms
of administrative actions, after review of the facilities
plan and the environmental impacts of construction of the
proposed project, EPA could: 1) fund the project as described
and recommended by the applicants, 2) not fund the project,
3) provide funding at a level below that requested by the
applicants, 4) provide funding in excess of the level re-
quested by the applicants, 5) fund the project in stages,
or 6) fund the project only after attaching certain condi-
tions to the grant award. These administrative actions would
be in response to regulatory requirements, funding availability,
environmental concerns or some combination of all three.
If EPA determines that the projects selected by the
City of Boise and the EWSD were excessive in cost or would
result in adverse environmental impacts which could be miti-
gated, it may wish to remedy these problems by placing condi-
tions on the award of subsequent grants rather than supporting
a different alternative or modifying the funding. EPA admini-
strative procedures allow this mitigation approach and place
the burden of action on the grant applicant. Grant conditions
can include specific monitoring requirements, requests for
supporting ordinances, or a variety of other controls on
the construction and operation of wastewater treatment and
disposal facilities.
Other Alternatives Considered
A number of other alternatives were considered by the
Boise facility plan engineers. These included land disposal
of treated effluent, expanding Gowen Field facilities, landfill
disposal of sludge, various locations of interceptors, possible
river crossings, river flow augmentation, sludge treatment
and transport, aerobic digestion, and location of sludge
disposal sites.
These were considered in preliminary studies but were
dropped because of adverse cost or environmental effects.
City and Facilities Plan Recommendations
The EWSD has recommended that Alternative D (rapid
infiltration and discharge to the Boise River) be implemented.
The Boise facility plan engineers have recommended that the
Lander Street plant be modified to meet discharge requirements
VI
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with no increase in capacity; also, that the West Boise treat-
ment plant be expanded in a two-stage approach, including
anaerobic digestion and disposal of liquid sludge by agri-
cultural use by pipeline transport to the state prison farm.
Description of Alternatives
Boise (Figure 2).
Treatment.
o Lander Street plant to remain at present capacity
with minor modifications to meet effluent discharge
requirements. These modifications include dechlorina-
tion and more efficient use of methane gas.
o West Boise plant to have major facilities expanded
in a two-stage approach. First stage in 1983 would
add 10.7 MGD of capacity, increasing total capacity
to 17 MGD. Three sludge digestion alternatives would
be considered. These include continued aerobic
digestion; continued aerobic digestion with modifi-
cation to simplify conversion to anaerobic digestion;
and conversion to anaerobic digestion. The second
stage would include construction of an equal capacity
plant (17 MGD) adjacent to the present and Stage 1
expansion facilities.
o Three basic sludge management alternatives have
been defined:
Digested (liquid) sludge truck transport to agri-
cultural use/disposal.
Digested (liquid) sludge pipeline transport to agri-
cultural use/disposal.
Digested sludge (dewatered) with truck transport
and landfill disposal.
o Three alternative sludge pipeline corridors (Figure 6)
o Four alternative interceptor alignment plans have
been studied for the North Boise area. These include
four plans as shown in Figure 4.
o Four alternative alignments and two additional routings
were studied for the South Boise area (Figure 5).
Vll
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FIGURE 2.
EXISTING SEWER SERVICE
-LEGEND-
WEST BOISE
UNDER STREET
P] GOWEN FIELD
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:GEND-
- — EAGLE FACILITY PLAN STUDY AREA
. .... EAGLE FACILITY PLANNING AREA
•••— CORPORATE CITY LIMITS
| EXISTING FACILITY SITE
PROPOSED FACILITY SITE
''
MILES (APPROX. )
FIGURE 3. FACILITY PLANNING AREAS FOR THE EAGLE
WATER AND SEWER DISTRICT
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MAINS AREA SERVED BY
ALTERNATIVE MAINS INCLUDED NOT INCLUDED LI FT STATION
PLAN 1 A. C &B
PLAN 2 A, C &F
PLAN 3 A, E 8.F
PLAN 4 A, E 8.B
D D
E a B [ 1
C & B [~ |
n n
\
•C*^^- MAIN D
"T* -NLI FT STATION,
15
'!" T*-.v,M <„,,'.-..:> .-- •'' V^/%";^|yj/\i
e-«; ^/,>l, W
/V
MAIN F
jl ' .WAIN B
O
,!:!•'
i-WIAINC
1 \ /
\s^
WEST BOISE \
TREATMENT PLANT '
MAIN A
XN
SOUTH BOISE
INTERCEPTOR
* \- i A ii'x^vs
• P x>. ^ Tt!—^
^,--i
^BOUNDARY
^ V> '.Mj -li-'-'
• STATE STREET :N\ "
'., SE;R,VICE AREA \ A •
:.:•; /k
GLENWO(bD STREET !•
INTERCEPTOR.. J• *. /_ -j. !_iv-.
POINT OF'F?LOW DIVERSION TO NORTH
,„ BOISE INTERCEPTOR
' / GLENWOOD STREET
PUMP STATION
FIGURE 4.
NORTH BOISE INTERCEPTOR ALTERNATIVES
-------
-LEGEND-
— ALTERNATIVE INTERCEPTOR ROUTES
— — FUTURE INTERCEPTOR EXTENSION
Existing
South
Interc
Lander Street
Wastewater
Treatment Plant
RiyER WEST., ,,;
r ' ••s-
_1T .*--•*:• INLAND
RIVER "EAST' ., <^ [N Point
'* '^'1 N
' ' y^V^VH';;. .,
L__:__X ^y*/^y?c3^\S^' . ' 1 '
*l £ ux ;\ Future Extension
" •""••' I South Boise
1 Interceptor >
uJfeGrme Sd)!!.'.".".!!!.'.:!!
FIGURE 5. ALTERNATIVE SOUTH BOISE INTERCEPTOR ROUTES
-------
WEST BOISE TREATMENT PLANT
. '/" PUMP STATIC^ NO.1 • -
- PUMP STATIONING..?
r ALTERNATIVE _A" "'j**
. . .........^ .. ^
.-':, .-I £1^" -''' "
£1; -LANDER STREET TREATMENT PLANT
PUMP STATION NO.2 ,., - !
• --±-' .^ -"' "
- •-:~i-^~'^-~~r—.:-.
j ALTERNATIVE_B ;
J. '-PUMP .STATIQNJNQ^^lr^;"^
ALtERNAfiVEC
~" -J- ''• • ' - '-' '"'
"CURTIS ROUTE'i^V:^-?
HILLIP,P4 .
.... ^ _ ._, .-. .- ,v^ _. .--
. J GOWEN FIELD TREATMENT PLANT 1 '^ORCHARD
: PUMP STATION NO. 4; v '-|\ -v-.vi-
.S.
'A v»
PRISON AREA AGRICULTURAL
LAND APPLICATION SITE STORAGE.
AND PUMP STATION LOCATION
.- PRISON FARM B_OUNDARY-
• PLEASANT ..VALLEY.
Ln
MILES
FIGURE 6. SLUDGE PIPELINE ROUTING
& LAND APPLICATION SITE
xii
-------
Eagle (Figure 3). Five waste treatment alternatives
have been studied. These include:
o Alternative A - oxidation ditch and discharge to
the Boise River.
o Alternative B - pump to West Boise treatment plant.
o Alternative C - land application by irrigation.
o Alternative D - rapid infiltration with discharge
to the Boise River.
o Alternative E - on-site disposal.
Southwest Community (Figure 1). Three wastewater
treatment alternatives were developed by the APA Southwest
waste management program. These include:
o Central wastewater collection system and treat-
ment at the West Boise treatment plant.
o Central wastewater collection and treatment at a
Southwest community wastewater treatment plant
with land disposal of effluent.
o Wastewater collection and treatment at community
lagoons with land disposal of effluent at
separate sites or a common site.
Three variations to these alternatives were evaluated: Plan A
urban growth, Plan B - urban reserve, and Plan C - rural
lifestyle. The Board of Ada County Commissioners in August
1980, adopted Plan C - rural lifestyle land use plan allowing
for 1 unit per 5 acres. As a result of that decision, the
use of individual on-site surface disposal systems became
the only feasible wastewater management alternative for
the Southwest community.
Operation Management Program Alternatives.
o Mandatory operation and maintenance program.
o Volunteer/mandatory operation and maintenance program.
o Volunteer operation and maintenance program.
o No-action program.
Xlll
-------
Impacts of the Proposed Alternatives
The environmental impacts and potential mitigation measures
for the project alternatives are summarized in the following
tables. Only the more significant or potentially significant
impacts have been summarized.
Following the tables is a short narrative summary of
these impacts.
The mitigation measures listed are possible methods
of avoiding or reducing the severity of adverse impacts.
Mitigation measures are not necessarily those that will be
implemented should a project be constructed. The adopted
mitigation measures will be included in EPA's Record of
Decision on the project, which will be prepared after the
completion of the Final EIA. EPA will not be responsible
for all mitigations required. Local, regional, and state
agencies will be called upon to initiate those mitigation
measures that are within their respective functional capa-
cities .
Summary Comparison of Alternatives
Under the no-action alternative, presently unsewered
areas will continue to constitute a threat to surface and
groundwater quality. This could result in fish mortality
in the Boise River, particularly under low flow conditions
and to potential public health problems for groundwater
contamination by septic tanks.
Upgrading the Boise Lander Street plant will remove
water quality problems associated with chlorine and ammonia
now entering the Boise River.
Modifying the West Boise plant to include anaerobic
digestion and increased hydraulic capacity will permit the
sewering of areas not now sewered, as well as accommodating
new growth.
The anaerobic digestion will permit a significant reduc-
tion in net energy consumption due to methane recovery and
use in facilities equipment.
Installation of the proposed North Boise and South Boise
interceptor lines will accommodate growth as well as provide
for sewering of areas using on-site treatment. The most
significant potential impacts will result from river crossings
crossing Eagle Island, and destruction of riparian habitat
in areas near the Boise River bank. These impacts may be
mitigated by controlled and approved construction methods,
and by revegetation and by limitations on land use within
the pipeline corridors.
xiv
-------
Table 1. Impacts
(Landers Street, West Boise, and Eagle Treatment Plants)
Area of Impact
Description of Impact
Possible
Mitigation Measures
Direct
Groundwater quality
Eventual elimination of on-site None
wastewater disposal system.
Centralized treatment capacity None
for new residents.
Surface water quality
Elimination of wastewater dis-
charges to the Boise River that
violate state and federal waste
discharge requirements assuming
dependable water flows.
Negotiate dependable
water flows from Lucky
Peak Reservoir.
Sludge disposal area
health threat
No significant impact upon public
health or groundwater as proposed
and described in Boise facilities
plan. Eagle disposal method has
not been described.
None
Costs
No significant difference in
cost between present aerobic
digestion and anaerobic dig-
estion in the West Boise plant.
No significant difference in
cost between North Boise inter-
ceptors.
Truck transport of liquid or
dewatered sludge is 4-6 times
as expensive as pipeline
transport.
Boise user charge for average
domestic household system will
increase from $7.70 per month
to approximately $8.60 per month
for Stage 1 improvements, and
to $9.20 per month for Stage 2.
None
Convert to pipeline trans-
port of sludge.
None
Growth
Growth implications
population increase
Approximately 214,000 popula-
tion will be accommodated on
Boise sewer system. Net
increase of 88,000 by year
2000.
Eagle would increase from
approximately 4,500 to 13,300,
an increase of 8,800.
Loss of agricultural land.
xv
Encourage infill and
increased urban densities.
Limit amount of urban
development.
Increase density of
urban development.
Allow development only
on land not suited for
agricultural use.
Preserve existing
agricultural uses.
Limit expansion or
extension of urban
services.
Strengthen competitive
position of agriculture.
Use tax incentive to
encourage agricultural
uses or discourage urban
uses of agricultural
lands.
-------
Area of Impact
Description of Impact
Possible
Mitigation Measure
Decreased air quality
Vegetation, fish and wildlife
will be adversely affected by
loss of habitat due to develop-
ment, and by disturbance due to
humans and pets in and near
developed areas or increased
recreational areas.
Drainage - as increased devel-
opment occurs there will be
increased runoff, sedimentation
and potential flooding as
a result of construction and
changes in drainage patterns.
Develop and implement
air quality maintenance
plan.
Carpooling, bicycle
routes, mass transit,
etc., as now being
studied by APA.
Plan urbanization and
recreation within Barber
Park to minimize bald
eagle disturbance.
Direct development
away from long billed
curlew nesting areas.
Implement drainage and
runoff control measures
to prevent sediment
from entering streams
and rivers.
Designate agency to
implement countywide
drainage planning and
facility maintenance
and administration.
Seek legislative clari-
fication to provide
full drainage authority
and funding.
Develop, adopt, and
implement consistent
drainage criteria.
Prepare, adopt and
implement drainage
master plans.
Resource and energy
use
Population increase in sewered
areas will use energy in the
residential and transportation
sectors and stimulate consump-
tion in the industrial and
commercial sectors.
Institute energy con-
servation measures.
Traffic
Population growth supported by
increased wastewater treatment
capacity will add traffic loads
to the existing roadway system.
Develop local traffic
plan considering air
quality attainment
standards.
Southwest area
groundwater
There would be no significant
adverse impacts under rural
lifestyle plan.
Establish regular moni-
toring programs of shallow
and deep groundwater
quality. Implement
APA comprehensive plan
on-site waste management
program.
Construction Related
Noise, dust and erosion
Short-term impacts from con-
struction of interceptors,
and sludge pipelines (river
north, river west, and Adams
Street).
No significant adverse impacts
from Eagle pipeline construction.
Equip internal combustion
engines with adequate
mufflers.
Limit construction to
daylight working hours.
Use normal dust control
measures.
Revegetate exposed area
following construction.
None
-------
Area of Impact
Description of Impact
Possible
Mitigation Measures
Vegetation and
wildlife
Proposed Eagle alternative
projects will eliminate signi-
ficant amounts of important
riparian wildlife habitat.
Proposed South Boise inter-
ceptor routes located
near the river would destroy
riparian habitat. River
north and river west would
destroy 5-7 acres.
Proposed North Boise inter-
ceptor routes would have
significant adverse impacts
on vegetation where Main A
would cross Eagle Island to
the river and where Main E
would cross the river. A
great blue heron rookery
would be disrupted.
EPA and City of Eagle
will evaluate alterna-
tive sites that may
avoid or lessen the
impact upon the existing
wetland.
If no feasible alterna-
tive exists, EPA will
propose mitigation
measures to be coor-
dinated with the U. S.
Fish and Wildlife Service.
Locate pipelines to
avoid riparian habitat
where feasible. Other
land uses should be
avoided in pipeline
corridors which would
prevent re-establish-
ment of vegetation
or result in distur-
bance by humans.
Fisheries
All of the Boise interceptor
and sludge lines would cross
the river at least once with
temporary adverse effects
upon the biota. These impacts
will not be significant if
conducted as advised by the
Idaho Department of Fish and
Game, and by the U. S. Army
Corps of Engineers.
Consult with Idaho
Department of Fish and
Game and the U. S. Army
Corps of Engineers for
specific mitigation
methods. These include
avoiding discharges in
spawning areas during
spawning seasons. Avoid
discharges in wetlands.
Reduce the watercourse
to preconstruction
bottom contours and
remove excess materials
to upland disposal site,
and others.
Cultural and
archeological
resources
No cultural resources have
been identified at the pro-
posed Eagle treatment site
or along the proposed Boise
interceptor sludge lines.
Excavations have the poten-
tial for disturbing previously
unknown historical or archeo-
logical sites.
Excavations in areas de-
signated by the state
archeological officer
as potential sources of
archeological artifacts
should be conducted as
advised by professional
archeologists. The state
archeologist should be
kept informed of the
progress of the proposed
project and the opportu-
nity provided for pro-
fessional examination of
excavated sites and
materials.
Description of
effluent flow
Disposal of effluent during
phases of new construction
could be impaired.
Retain existing pipe-
lines, pumping stations,
etc., until new facil-
ities are put into
operation.
Traffic
congestion
Excavation and placement of
interceptors and sludge pipe-
line will temporarily disrupt
traffic.
Reroute trucks with
oversized loads, and
avoid peak traffic
periods and major local
arterials.
xvi i
-------
Possible
Area of Impact Description of Impact Mitiaation Measures
Resources and All of the proposed wastewater Recover methane gas from
materials treatment facilities will anaerobic digestion to
require the irretrievable aid in operation of
expenditure of energy and waste treatment equip-
materials. ment. Reduce pumping
loads, reduce infiltra-
tion/inflow in sewer
lines, and establish
water conservation pro-
grams .
-------
Table 2. No-Action Alternatives
Possible
Area of Impact Description of Impact Mitigation Measures
Construction None
Surface water quality Occasional elevated levels of
chlorine, total suspended
solids, and ammonia nitrogen
(Boise). Present Eagle
system is designed for 3
year interim period. Expect
violations of NPDES ,discharge
permit conditions.
Boise River Potential toxic levels of Add dechlorination ore-
fishery ' ammonia and chlorine may be cess.
discharged. Augment river flow.
Resources use Continue high energy costs of Use pipeline transport.
transporting sludge to dis-
posal site by truck (Boise).
Continue aerobic digestion of Convert to anaerobic
West Boise plant; this will digestion; this will
require net 1,830 kilowatt require a net of 920
hours per MGD. kilowatt hours per
MGD.
Archeological None
resources
Growth Local growth can be reduced
implication or halted.
xix
-------
Disposal of liquid sludge by pipeline at the state prison
farm will be the most energy conserving alternative and will
permit the beneficial use of sludge as a fertilizer under
controlled disposal and monitoring conditions.
The proposed Eagle wastewater treatment facilities will
destroy significant areas of riparian wildlife habitat. The
loss of wetlands to treatment ponds, buildings, parking lots,
roads, and other construction-related activity is not mitigable,
Loss of habitat to pipelines may be mitigated by revege-
tation and limiting land use within corridors.
Both the Boise and Eagle proposed wastewater treatment
projects will accommodate significant growth in the Boise-
Eagle area, and a number of significant growth-related impacts
will result.
These impacts, due to increased growth, include further
deterioration of air quality in Boise. A decrease in the
adequacy of public services, increased drainage problems,
loss of valuable agricultural land to urban uses, conflicts
with wildlife and fisheries uses through loss of habitat
to development and possible disruption or loss of cultural
or historic resources due to physical changes of development.
These potentially significant impacts may be mitigated through
development and implementation of land use plans.
The design for the Boise wastewater treatment facilities
assumes a dependable, adequate flow in the Boise River. Thus,
it will be essential that a minimum water flow release from
Lucky Peak Reservoir be negotiated with the U. S. Water and
Power Resources Service.
xx
-------
Chapter 1
Introduction
-------
Chapter 1
INTRODUCTION
The EIS Process
National Environmental Policy Act of 1969 (NEPA) requires
that all agencies of the federal government must evaluate
the environmental consequences of actions they undertake
or sponsor. Consistent with other essential considerations
of national policy, agencies are directed to avoid or mini-
mize possible adverse effects of their actions on the quality
of the human environment. The major implementation tool
of NEPA is the Environmental Impact Statement (EIS). An
EIS serves as a decision-making document which describes
and analyzes alternative actions or projects. The EIS process
serves as a means of obtaining input into agency decisions
from other federal agencies, state and local agencies, and
the^general public.
The EIS process also provides a means for ensuring that
project planning considers the requirements of applicable
"laws and policies. Examples of broadly applicable federal
legislation include the Clean Water Act, the Clean Air Act,
the Safe-Drinking Water Act, the Endangered Species Act,
the Fish and Wildlife Coordination Act, and the National
Historic Preservation Act. Various Executive Orders and
agency policies also must be considered in connection with
the protection of floodplains, wetlands, and prime farmland.
A
Grant Programs Under the Clean Water Act
The federal Clean Water Act establishes a basic goal
of achieving "fishable, swimmable" surface waters throughout
the country by 1983, and the elimination of pollutant dis-
charges by 1985. The act establishes a permit system (National
Pollutant Discharge Elimination System [NPDES]) to regulate
the discharge of pollutants to waters of the United States.
The various provisions of the Clean Water Act are administered
by the U. S, Environmental Protection Agency (EPA). The
responsibility for processing NPDES permits is normally
transferred to state water quality agencies, with EPA re-
taining a review and approval role. In Idaho, NPDES permits
are processed by the Idaho Department of Health and Welfare.
-------
Section 201 of the Clean Water Act provides a program
to help meet the costs of upgrading publicly-owned wastewater
treatment systems. These "clean water grants" administered
by EPA provide up to 75 percent (or up to 85 percent for
innovative treatment/disposal systems) of the planning and
construction costs for eligible facility improvements. In
order to receive this funding assistance, local wastewater
management projects must be planned and designed in accor-
dance with various EPA requirements.
Section 208 of the Clean Water Act provides a separate
grant program to fund studies of "areawide" water quality
problems.
Background to Development of This EIS
A number of public wastewater treatment systems in Ada
County have received EPA grant funds in recent years, in-
cluding facilities for the City of Meridian and the City
of Kuna. Recently, the City of Boise and the Eagle Sewer
and Water District also initiated facility planning programs
under the Clean Water Grant program. In addition, the Ada
Planning Association requested grant funds to evaluate waste-
water management alternatives in the rural portions of Ada
County. Particular attention was focused on the area south-
west of Boise.
EPA decided that a single EIS should be prepared to
evaluate proposed wastewater management projects in the Boise
area. While the individual projects can be analyzed separately,
the significance of project-specific impacts is best determined
from an areawide or cumulative perspective. The individual
projects under consideration include those of the City of
Boise, the Eagle Sewer and Water District, and the Ada Plan-
ning Association's Southwest Area study.
Report Format
This EIS is organized into chapters which discuss general
topic areas investigated during report preparation. The
initial chapters provide information on the wastewater manage-
ment programs planned for the area. Subsequent chapters
discuss major topic areas related to potential impacts. Each
such chapter includes discussion of essential background
information, relevant project details, impact analyses, and
potential mitigation measures. Some of the chapters in this
EIS are based on special studies described in more detail
by separate study reports or appendix documents.
-------
Several reports have been prepared specifically for
this project, and represent a considerable amount of supple-
mental technical information which may be useful to those
reviewing this Draft EIS. These reports include:
o Ground Water Resources p_f Boise Valley, Idaho,
H. Esmaili & Associates, Inc. June 1980.
o Nonpoint Source Waste Loadings in Ada County
and Southwest Community Study Area, H. Esmaili &
Associates, December 1980.
o Drainage Task Report - Drainage Planning and
Institutional Evaluations, Jones & Stokes
Associates, Inc. February 1980.
o A Tethersonde Field Study Examining Low Level
Stability in the Boise Valley, North American
Weather Consultants. April 1980.
o Ozone Data for Ozone Special Study, Boise, Idaho,
Earthmetric's Incorporated. November 1979.
These reports are available for review in the EPA Boise
office. If a strong need is identified by a reviewer, a
copy of the required report will be provided.
In addition, other technical information which has been
developed as background for this Draft EIS has been included
in a separate appendix. This appendix may be reviewed in
the EPA Boise office, or requested from the EPA, Region 10
headquarters in Seattle.
-------
Chapter 2
Coordination
-------
Chapter 2
COORDINATION
Introduction
Section 6.203 of the EPA procedures for implementation
of the National Environmental Policy Act (Federal Register,
Vol. 44, No. 216, November 6, 1979) requires that all EISs
discuss the extent and results of coordination activities
conducted prior to publication of EISs. This chapter describes
the involvement of government agencies, special interest
groups, and the public in general in determining the scope
and content of this EIS. It also describes, how, when, and
where coordination efforts will continue.
Coordination Efforts to Date
Scoping meetings were held in Boise on March 23, April 24,
and May 9, 1979. At that time the contractor met with repre-
sentatives of EPA, state, and local agencies.
The discussions at these meetings centered on: 1) the
issues associated with the proposed Ada County water quality
management plan being prepared by the Ada Planning Association
(APA) under Section 208, 2) the work plans and schedules
.of the planning projects to be funded by EPA, and 3) the
coordination of the EIS with the environmental review of
the funded projects.
The principal issues discussed included the following:
o Water quality standard vs. wastewater treatment
and disposal and augmentation of instream flow
in the Boise River.
o Evaluation of status of programs and projects con-
cerned with population distribution and density
vs. air quality maintenance programs designed to
achieve air quality compliance for carbon monoxide.
o Community wastewater facilities plans vs. APA and
local community ordinances, policies, and goals to
conserve and,manage land and water resources.
o Population distribution and density vs. cost-effective
wastewater treatment and disposal.
o Population distribution and density vs. the quality
of drinking water supplies for communities and
individuals.
5
-------
o The effects of land use plans on the long-term
beneficial uses of groundwater resources.
o The effects of land use plans on the long-term
beneficial uses of surface waters and riparian lands.
o The requirements to meet air quality and water quality
standards vs. implementation schedules for EPA grant-
fundable projects.
o Public participation and the adequate presentation
of sufficient information to understand the cumulative,
secondary effects of funded projects on the renewable
natural and socio-economic resources.
o The primary and secondary economic impacts of popu-
lation distributions not in conformance with the
comprehensive plan on land owners and a community
ability to provide social and utility services.
On May 13 and 14, 1979, three workshops were held in
Boise covering issues associated with air quality, surface
water and groundwater.
These workshops were followed by a public meeting in
Boise on May 14, 1979. This public meeting was publicized
by the mailing by EPA of 150 flyers to interested parties
in the study area. In addition, many flyers were posted
in post offices and public buildings in Boise and the sur-
rounding area including Eagle. The Idaho Statesman high-
lighted the scheduled meeting.
The public did not respond to this publicity and only
personnel from the various agencies concerned with the pro-
posed project appeared at the meeting.
The EPA issued a Notice of Intent (NOI) to prepare an
EIS on June 7, 1979, following a meeting with facilities
plannin-g personnel and APA representatives.
Numerous contacts with individuals and agencies have
been made by the EIS contractor during frequent trips to
Boise in the course of this study. Progress reports have
been made on occasion to the APA staff and board.
A representative of the contractor was located in Boise
for approximately 6 months in the APA offices as a coordina-
tor with both the EPA and APA representatives.
-------
In addition to the specific meetings and contacts
referred to above, several committees in Ada County are
actively considering a number of issues which relate to
the preparation of the EIS. These committees include:
o Wastewater Management Study Committee
(advisory committee)
o Transportation, Citizens Advisory Committee
o Air Quality, Citizens Advisory Committee
o Air Policy Committee
o Technical Advisory Committee for Transportation
There is also a Growth Committee in the comprehensive
planning section of APA. However, this group has not yet
addressed the issues relating to the Draft EIS.
Continuing Coordination Efforts
This Draft EIS has been forwarded to numerous federal,
state, and local agencies, special interest groups, and private
citizens. It is an informational document for review and
comment on the proposed wastewater projects. The distribution
list can be found on page 257. The document has been forwarded
to the Boise and Eagle public libraries to enable residents
to review potential impacts of the project.
Individuals or groups that wish to comment on the EIS
may forward written comments to:
Ms. Norma Young, M/S 443
U. S. Environmental Protection Agency, Region 10
1200 Sixth Avenue
Seattle, Washington 98101
EPA will conduct a public hearing to solicit oral comments
on the Draft EIS and the Eagle and Boise wastewater facilities
proposed projects on April 30, 1981 at 7:30 p.m. at:
Les Bois Room
Third Floor, Boise City Hall
Boise, Idaho
All oral and written comments received on the Draft EIS will
be recorded and responded to in a Final EIS which will be
available to interested individuals, groups, and agencies
approximately 2 months after the public hearing.
-------
Chapter 3
Water Quality Management in Ada
County
-------
Chapter 3
WATER QUALITY MANAGEMENT
IN ADA COUNTY
Locational Setting
Ada County, Idaho is located north of the Snake River
in the southwestern part of the state (Figure 3-1). Encom-
passing 673,000 acres, most of the county is between 2,500
and 3,300 feet elevation. The northeastern portion of the
county includes the slopes of the Boise Front, which rises
to elevations of about 5,900 feet. The southern part of
the county is primarily desert, with urban and agricultural
areas concentrated in the northern half of the county- The
northern half of the county is drained by the Boise River,
which joins the Snake River along the border between Idaho
and Oregon.
»
The City of Boise straddles the Boise River, with the
northern portions of the city against the lower slopes of
the Boise Front. The southern part of the city occupies a
series of river terraces (benches) rising south of the Boise
River. The City of Eagle is also located along the Boise
River, about 9 miles northwest (downstream) from downtown
Boise. The City of Meridian is located about 9 miles due
west of downtown Boise, while the small Town of Kuna is
13 miles southwest of Boise. The Cities of Nampa and
Caldwell in neighboring Canyon County are about 18 and 24
miles west of Boise.
Existing Wastewater Treatment Facilities
Each of the municipal wastewater management facilities
in Ada County consists of two basic components — a collection
system and facilities for treatment and disposal of the
collected sewage. The wastewater collection systems involve
networks of pipelines and pump stations which collect sewage
from individual homes, businesses, and industries, and carry
it to the wastewater treatment plant.
City of Boise Facilities
The City of Boise is served by three wastewater treatment
plants (Figure 3-2). The Gowen Field plant serves the area
-------
,_21
A
H
A
GEM CO.
CANYON CO.
T
\<
%± ***.
MILES
\
\
\
\
-LEGEND-
i»'i»ii BOISE VALLEY BOUNDARY
ADAPTED FROM MACE,1963
BASE MAP: USeS 1:Z50,000 "BOISE",
REVISED 1976
FIGURE 3-1. REGIONAL SETTING
10
-------
FIGURE 3-2. SEWER
AREAS IN THE BOISE
METROPOLITAN AREA
SERVICE
NORTHWES7 _
BOIS ^CEWEI/DISTRICT
SEWlER
DISfRICT
SOWEH
FIELD
PLANT "*• CO WEN
-------
around the Boise municipal airport. The recently completed
West Boise plant serves the western portion of the Boise
area. The Lander Street plant serves most of the City of
Boise.
Gowen Field Treatment Facilities. The Gowen Field treat-
ment plant was built during World War II (1942) by U. S.
Army Engineers. The original plant, a high-rate trickling
filter, discharged to the upper part of Five Mile Creek.
Due to overloading during the summer caused by training of
National Guard units, however, the tricking filter system
was abandoned and a lagoon system was constructed in 1976.
Treated effluent is stored during the winter. During the
summer, the effluent is used to irrigate 47 acres of alfalfa
The Gowen Field system currently serves the Gowen Field National
Guard facilities, the airport, the Boise Industrial Park,
the Bureau of Land Management Fire Control Center, and the
commercial facilities by the airport and interstate highway.
The treatment system has a design capacity of 0.512 MGD
(million gallons per day). The storage at the treatment
plant is ample to accommodate 0.5 MGD throughout the year,
and at these flows, irrigation would have to occur approxi-
mately 7 months out of the year. Because effluent is stored
during the winter, plant capacity is lower during that period.
Lander Street Treatment Plant. The Lander Street plant
is located on the north side of the Boise River in the north-
western part of Boise. Following chlorination, secondary
treated wastewater is discharged directly into the Boise
River at approximately River Mile 49.7. The plant was built
in 1950 as a conventional activated sludge plant with anaerobic
digestion. The plant was subsequently modified in 1960-
1961, 1968-1969, 1971, 1973, and again in 1975. The existing
plant layout is shown in Figure 3-3. The hydraulic design
capacity of the facility is 15.0 MGD and 23,000 pounds per
day biological oxygen demand (BOD) and total suspended solids
(TSS) removal. The Lander Street plant had a peak month
discharge of 13.1 MGD in 1978 (CH2M Hill 1979b) and 14.6
MGD in 1979 (CH2M Hill 1980a). These peak month flows occurred
during the summer. Sewage flows from the Bench Sewer District
also enter the Lander Street Plant for treatment.
West Boise Treatment Plant. The West Boise treatment
plant, built in 1975, is located south of the Boise River
near the north end of Cloverdale Road. The West Boise treat-
ment plant uses an activated sludge secondary treatment process.
Treated effluent is discharged to the Boise River at approxi-
mately River Mile 45. The existing treatment plant layout
is shown in Figure 3-4. The treatment facilities are rated
at 6.3 MGD hydraulic capacity, 15,000 pounds per day BOD
removal, and 15,000 pounds per day TSS removal (peak month
flow basis). The West Boise plant had a peak month discharge
of 5.28 MGD in 1978 (CH2M Hill 1979b) and 7.4 MGD in 1979
(CH2M Hill 1980a). Peak flows occurred during the summer.
12
-------
Figure 3-3. Lander Street Treatment Plant Site Plan
n ^£&*.T/ON &A&IN NO. *> :
&*&IN NO- i
SOURCE: CH2M Hill 1979a.
-------
Figure 3-4. West Boise Treatment Plant Site Plan
f
1 s
/• ~\
' — x~ ^n
(1 [ 1/wiueM— -I.
\\\fUMf
y s^nou-
) ZCfftp/HG t
( 3frt£ODlWT~.
zrxL'cri/'-f-x'
->
IHtVf.Y -^ \
CITY OF soise FACILITIES
SOURCE: CH2M Hill 1979a.
-------
Eagle Water and Sewer District
The existing sewage treatment facilities of the Eagle
Water and Sewer District (EWSD) were constructed in 1965
and modified in 1975 and 1978. The plant site is located
north of the Boise River, west of Eagle Road (Figure 3-5).
The existing treatment system consists of two sewage lagoons
and two sand filters.
Sewage is pumped into the first pond (1.2 acres) which
is aerated by a perforated plastic pipe system. Effluent
from the aerated lagoon flows into a second lagoon (1.8 acres)
which does not have any special aeration system. The ef-
fluent is then pumped to the sand filters (0.41 acre each).
After percolating through 2 feet of sand, the effluent is
collected by an underdrain system and discharged to the Boise
River at river mile 46.25.
The existing facilities have a design capacity of 0.3
MGD for winter and 0.5 MGD for summer. Summer flows have
averaged 0.35 MGD (peak summer flows of 0.425 MGD) with an
average winter flow of 0.17 MGD (J-U-B Engineers 1980).
Southwest Community Wastewater Management Study
The rural area southwest of Boise (Figure 3-6) contains
a mixture of agricultural and large lot residential develop-
ments. The area currently has a population of about 14,000.
Most residents currently rely on individual septic
tanks for wastewater disposal. The Owyhee Sewer District
operates a small treatment plant which serves the Indian
Lakes subdivision. This facility employs lagoon treatment
with land disposal of the effluent. About 920 dischargers are
currently connected to this system. The Owyhee plant has
a design capacity of 0.35 MGD (Ada Planning Association
1979a). In addition, there is one small package plant (ex-
tended aeration and drainfield disposal) serving a truck
stop development. One community septic tank system has also
been constructed recently.
Concern over the nature of development and associated
wastewater disposal practices prompted the APA to initiate
an areawide wastewater management study funded under Section
208 of the Clean Water Act. The major objective of the study
was to determine whether a centralized sewer and wastewater
treatment system was needed for this area.
Facility Problems
Wastewater management projects and studies have been
initiated by the City of Boise, EWSD, and APA. These studies
are intended to resolve the problems discussed below.
15
-------
Figure 3-5. Eagle Water and Sewer District Facilities
FLOATING / FEATHER
LEGEND
^ Eagle Water and Sewer
District Boundary
EXISTING TREATMENT
SOURCE: J-U-B Engineers 1980,
-------
Figure 3-6. Southwest Community Wastewater
Management Study Area
STUDY AREA
BOUNDARY
SOURCE: Ada Planning Association 1979a
17
-------
Gowen Field Treatment Plant
The Gowen Field treatment plant is currently operating
at an annual average of 40 percent of capacity. No signifi-
cant problems have been identified at this plant. The avail-
able capacity is expected to serve development in the treat-
ment plant service area until about 1995 (CH2M Hill 1980a).
No facility improvements have been proposed for this treat-
ment plant.
Lander Street Treatment Plant
During 1979 peak month sewage flows reached 97 percent
of the facility design capacity while BOD loadings reached
94 percent of design capacity and TSS loadings exceeded design
capacity by 2 percent (CH2M Hill 1980a). Continued growth
in the service area for the Lander Street plant will increase
flows and organic loadings above plant capacity.
The existing Lander Street discharge contains an ex-
cessive concentration of chlorine (used for disinfection).
Excessive concentrations of ammonia are also discharged at
some periods of the year. Both chlorine and ammonia can
be toxic to aquatic organisms.
West Boise Treatment Plant
During 1979 peak month sewage flows exceeded treatment
plant design capacity by 18 percent, while BOD and TSS loadings
were less than 40 percent of design capcity (CH2M Hill 1980a).
The excessive hydraulic loading at the West Boise plant appears
to be due to very high groundwater infiltration in the Garden
City sewer system (CH2M Hill 1979a). Continued growth in
the area served by the West Boise plant will cause further
overloading of the existing capacity. As at the Lander Street
plant, treated effluent contains levels of chlorine which
may be toxic to aquatic organisms. Industrial wastes received
at the West Boise plant have led to some concerns about the
combined effects of heavy metals and ammonia in the plant
effluent.
Eagle Water and Sewer District Facilities
With the recent construction of sand filters at the existing
plant, effluent quality has improved significantly. These
sand filters, however, are designed for only a few years
of use. Thus future effluent quality problems are expected.
Future development in the area served by the existing plant
could also create an excessive load on the facilities.
18
-------
Southwest Community Area
The wastewater management study undertaken by APA was
initiated due to concerns about possible groundwater pollu-
tion from septic tanks.
19
-------
Chapter 4
Wastewater Treatment Alternatives
-------
Chapter 4
WASTEWATER TREATMENT ALTERNATIVES
Introduction
The wastewater treatment alternatives discussed in this
EIS relate to two study areas; the Boise Metropolitan Area
(including the unincorporated Southwest 208 study area) and
the Eagle Water and Sewer District.
Facilities planning studies recently prepared for the
Boise Metropolitan Area by CH2M Hill and for the Eagle Water
and Sewer District by J-U-B Engineers, Inc., and a waste-
water management study prepared on the Southwest community
by Ada Planning Association (APA), were the major references
for description of the wastewater treatment alternatives.
City of Boise Facilities
The facilities planning effort for the City of Boise
has been focused on a number of aspects: 1) expansion of
treatment facilities at the existing Lander Street or West
Boise wastewater treatment plants, 2) modification of treat-
ment processes (i.e., nitrification and organics removal),
3) infiltration and inflow studies of Garden City and Boise
City, 4) interceptor systems, 5) sewage sludge management,
and 6) augmentation of stream flows in the Boise River.
In the preliminary draft facilities plan prepared by
CH2M Hill, it was assumed that the unincorporated Southwest
community would be served by the West Boise treatment plant;
however, during development of the Southwest Community Waste-
water Management Study by APA, a decision was made not to
provide central sewers to this area. Data from the Boise
facilities plan have been adjusted in this EIS to reflect
that decision. Additionally, alternatives for the South-
west community are discussed separately herein.
The development of facilities alternatives is typically
influenced by two major considerations: required levels
of wastewater treatment (discharge requirements) and required
facility capacity-
Discharge Requirements
The Idaho Department of Health and Welfare has estab-
lished water quality standards for the Boise River. These
21
-------
standards (discussed in Chapter 9) are intended to protect
a variety of beneficial uses in the Boise River. These
v/ater quality standards have in turn been used to set require-
ments for the level of treatment at the Lander Street and
West Boise wastewater treatment plants. These discharge
requirements are shown in Table 4-1.
Staging and Capacity Considerations
EPA regulations (U. S. EPA 1978a) provide basic guidance for
estimating future wastewater facility needs. Overall planning
is based on a 20-year planning period. In many cases, however,
actual facility construction will occur in stages during
this 20-year period. Facility planning for the City of Boise
involved projecting future sewage flows and waste loads for
the year 2000. Separate projections were made for different
subareas of the Boise area. Population forecasts for these
subareas were taken from the forecasts used by the APA (1978a).
Existing sewage flows and sewage generation rates were
determined from water usage data and special studies of sewage
flows in major trunk sewers. This is the existing sewer
service area shown in Figure 4-1. Separate estimates were
made for residential, commercial, industrial and infiltration
flow components. Projections for the year 2000 assumed that
there would be an increase in per capita or per acre sewage
generation rates for most flow components in most subareas.
These sewage generation rates (Table 4-2) do not incorporate
any water conservation measures, but do reflect programs
to control infiltration in the Garden City area.
Existing and projected sewage flows are shown in Table 4-3.
The projected residential flows are based on the population
projections shown in Table 4-4. These projections assume
that all new development will be sewered and that all existing
unsewered development will be connected during the next 20
years. While the total population of the Boise area is pro-
jected to increase by 68.6 percent between 1978 and 2000,
the facility plan anticipates a 120 percent increase in the
number of residents actually connected to the treatment plants.
Projected wastewater flows from commercial and industrial
development were based on projections of commercial and industrial
acreage for the year 2000 (Table 4-5). This is the proposed
sewer service area described in Figure 4-2. Existing commercial
and industrial acreages were derived from the 1978 zoning
plan for the City of Boise (CH2M Hill 1980c). Commercial
acreage was projected to increase in direct proportion to
population growth while future industrial acreage was esti-
mated from the Boise Metropolitan Planning Area map (CH2M
Hill 1980c).
Future infiltration flows were projected using the infil-
tration rates shown in Table 4-3. In general, increased
infiltration rates are projected for all areas. A program
22
-------
FIGURE 4-1
EXISTING SEWER SERVICE
-------
FIGURE 4-2
PROPOSED SEWER SERVICE
-LEGEND-
^ WEST BOISE
LANDER STREET
D GOWEN FIELD
AREAS
-------
Table 4-1. Boise Treatment Plan Effluent Limitations Future and Historical
Historical Limitations
ro
ui
Parameter
BOD
TSS
Dissolved Oxygen
Fecal Coliform
Irrigation (Recre-
ation) Season
Non-Irrigation
Season
Chlorine Residual
Ammonia Nitrogen
ruiuie
Limitation
Both Lander St.
& West Boise
20 mg/l
30 mg/l
6 mg/l or
75%
50/100 ml
100/1 00 ml
0.1 mg/l
Varies
Boise River
Lander St. Less than 1 20 cfsa
20 mg/l
30 mg/l
"
50/1 00 ml
50/1 00 ml
0.6 mg/l
18 mg/l
20 mg/l
30 mg/l
90%
50/100 ml
0.4 mg/l
3. 4 mg/l
West Boise
Boise River Boise River
Less than 1 70 cfsa Greater than \ 70 cfsa
30 mg/l
30 mg/l
90%
100/1 00 ml
0.6 mg/l
3.4 mg/l
30 mg/l
30 mg/l
80%
200/1 00m!
200/1 00 ml
0.6 mg/l
3.4 mg/l
aBoise River flow measured at Capitol Boulevard
SOURCE: CH2M Hill 1980c.
-------
Table 4-2. Sewage Generation Rates Used for the Boise Area
Subaroa
We it Boisu Sewer District
Garden City
North Boise, State Street,
Wust Chinden, Cloverdale,
and Five Mile Sewer Service
Areas
Bench Sewer District
Americana Blvd. Sewer
Service Area
South Boiso Sewer Service
Area
Table Rock Sewer Service
Area
Central Boise Sewer
Service Area
Northwest Boise Sewer
District
Residential
Flows
(gpcd)
1979 2000
62 65
60 65
60 65
61 65
54 , 55
64 70
59 65
60 65
55 60
Commercial
Flows
(gpjd)
1979 2000
800 800
715 800
650 800
900 900
NA 900
520 800
800 800
885 900
670 800
Industrial
Flows Ave
(cjpad)
1979 2000 1979
1,000 1,000 25
1,000 1,000 1,285
625 1,000 100
1 ,200 1 , 200 55
NA NA 55
1,000 1,000 175
1,000 1,000 230
1,200 1,200 300
NA NA 100
Inf iltration/ Inf low Rates
rage Month
(gpad)
2000
150
1,625
1 50
150
150
200 (150) :
250 (150) l
400
150
L'o -
1979
50
2,585
200
165
165
250
400
500
250
.k Month
2 0 0 U
250
2,500
250
250
250
50o (250) i
1,000 (250) >
1 ,000
500 (250) '
NOTES:
Sec Figure 3-2 for boundaries of sewer districts and sewer service areas.
NA = not applicable
gpcd = gallons per capita per day
gpad = gallons per acre per day
Value in parentheses applied only to new development after 1979.
DATA SOURCE: CH2M Hill 1980.
-------
Table 4-3. Existing and Projected Sewage Flows from Sewer Service Areas in Boise
Wastcwater Flow Component
Residential
Sewer Service Areas 1978 2000
Commorc.i al
J iiiluriLria I
1978 2000 1978
Infiltration Total
2000 1978
Annual Average
North Boise; State Street; West
Chinden; Cloverdale; Five Mile;
Garden City; West Boise Sewer
District 0.93 4.35
Bench Sewer District 1.71 2.30
Table Rock; South Boise 0.74 3.65
Central Boise; Northwest Boise
Sewer District 2.38 3.65
TOTAL 5.76 13.95
North Boise; State Street; West
Chinden; Cloverdale; Five Mile;
Garden City; West Boise Sewer
District 0.93 4.35
Bench Sewer District 1.71 2.30
Table Rock; South Boise 0.74 3.65
Central Boise; Northwest Boise
Sewer District 2.38 3.65
TOTAL 5. 76 13.95
0.38 0.80 0.
0.47 0.55 0.
0.11 0.60 0.
1.00 1.15 0.
1.96 3.10 1.
Peak
0.38 0.80 0.
0.54 0.55 0.
0.11 0.60 0.
1.02 1.15 x 0.
2.05 3.10 1.
17
30
30
56
33
Month
17
30
30
58
35
3.
0.
1.
0.
5.
Flows (MGD)
00 1.95
30 0.27
50 0.55
60 2.13
40 4.90
2000 1978 2000
3.50 3.43 11.65
0.75 2.75 3.90
2.35 1.70 8.10
3.25 6.07 8.65
9.85 13.95 32.30
Flows (MGD)
3.
0.
1.
0.
5.
00 3.90
30 0.81
50 0.90
60 3.62
40 9.23
5.60 5.38 13.75
1.25 3.36 4.40
5.05 2.05 10.80
7.60 7.60 13.00
19.50 18.39 41.95
NOTES:
MGD = million gallons per day
Sec F.i cjure 3-2 for boundaries of sewer districts and sewer service areas.
DATA SOURCE: CH2M Hill 1980.
-------
Table 4-4. Population Projections for Sewer Service Areas Served by the
Lander Street and West Boise Treatment Plants
Sever Service Area
1978 1985 1990 1995 200U
Total Sewered Total Sewered Total Sewered Total Scwurcd Total Suweivd
SSe^SivSSa?*^' XX, 35'°10 15'25° 46'°9° 3°'58° 54'145 4°'2°5 6l'95° 53'625 66'7a° bb'79°
Garden City; West Boise Sewer
District
Bench Sewer District
Table Rock, South Boise
Central Boise; Northwest Boise
Sewer District
TOTAL
31,410 28,700 33,060 31,125 33,270 31,980 34,110 33,465 35,805 35,805
17,000 12,000 27,580 24,020 38,275 35,870 47,700 46,490 53,840 53,840
42,390 40,500 46,420 45,035 49,285 48,300 52,560 52,040 55,710 55,710
125,810 96,450 153,150 130,760 174,975 156,355 196,320 185,620 212,145 212,145
See Figure 3-2 for boundaries of sewer service areas.
DATA SOURCE: CH2M Hill 1980.
-------
Table 4-5. Projected Commercial and Industrial Acreage in the Boise Area
Commercial Area Industrial Area
(acres) (acres)
Sewer Service Area 1978 2000 1978 2000
North Boise; State Street; West 565 800 215 1,360
Chinden; Cloverdale; Five Mile;
Garden City; West Boise Sewer
District
Bench Sewer District 520 600 250 250
Table Rock, South Boise 190 750 265 1,430
Central Boise; Northwest Boise 930 1,250 330 370
Sewer District
TOTAL 2,205 3,400 1,060 3,410
See Figure 3-2 for boundaries of sewer service area.
DATA SOURCE: CH2M Hill 1980.
-------
to eliminate 1.0 MGD of infiltration from the Garden City
area is assumed in the infiltration rates shown in Table 4-3.
Projected waste loads (biochemical oxygen demand and
total suspended solids) are shown in Table 4-6.
The no-action alternative includes a continuation of
treatment and discharge at the Lander Street and West Boise
treatment plants. The Lander Street plant discharges secondary
treated wastewater directly to the Boise River. This plant
had a peak month discharge of 13.1 MGD in 1978 and 14.6 MGD
in 1979 during the summer. The hydraulic design capacity
of the facility is 15.0 MGD. The plant is operating at capa-
city, both hydraulically and organically.
The West Boise treatment plant also discharges to the
Boise River with a peak flow of 5.28 MGD in 1978 and 7.4
MGD in 1979 during the summer. The treatment facilities
are rated at 6.3 MGD hydraulic capacity. The plant is
operating at hydraulic capacity, but is far below organic
capacity.
Development of Project Alternatives^
A series of technical memoranda has led to the develop-
ment and screening of treatment alternatives. This alterna-
tive development program for wastewater treatment facilities
was based on several key factors:
o The Gowen Field treatment plant will remain as is,
and continue to serve only the present service area.
o There is limited space available at the Lander
Street plant; the actual expansion limitations are
governed by the level of treatment required.
o The existing West Boise plant was designed with
expansion in mind and a parallel treatment plant
could be constructed at the existing plant site
to handle higher flows.
o There are certain effluent limitations governed by
seasonal flows in the Boise River.
Treatment Plant Expansion and Modification. Treatment
plant expansion was considered at the Lander Street and West
Boise treatment facilities. A cost-effective analysis and
evaluation of site constraints by CH2M Hill showed that the
Lander Street facility would be best suited to remain at
its present capacity with minor modifications necessary to
meet effluent discharge requirements. These modifications
include:
o Dechlorination to remove excess chlorine prior to
discharge. This would be accomplished by use of
a sulfur-dioxide and postaeration process.
30
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Table 4-6. Projected Waste Loads from Sower Service Areas in Boise
BOD Loads TSS Loads
(pounds per day) (pounds per day)
Sewer Service Area
North Boise; State Street; West
Chinden; Cloverdale; Five Mile;
Garden City; West Boise Sewer
District
Bench Sewer District
Table Rock, South Boise
Central Boise; Northwest Boise
Sewer District
TOTAL
Annual Average
1978 2000
2,600 12,025
4,880 6,445
2,140 9,800
9,880 13,775
19,500 42,045
Peak Month Annual. Average peak Month
1978 2000 1978 2000 1978 2000
3,325 15,395 2,610 12,025 3,785 17,435
6,245 8,250 4,880 6,445 7,075 9,345
2,740 12,545 2,080 9,745 3,015 14,120
12,655 17,635 9,140 12,965 13,255 18,800
24,965 53,825 18,710 41,180 27,130 59,700
Notes: BOD = biochemical oxygen demand
TSS = total suspended solids
DATA SOURCE: CH2M Hill 1980.
-------
o Changes for more efficient use of methane gas. The
cost-effective evaluation indicated that several
project components could operate on methane gas.
Expansion of major facilities was judged by CH2M Hill
to be best accommodated at the West Boise treatment plant.
That expansion would be accomplished in a two-stage approach;
the first expansion stage coming probably in 1983 and the
second in 1987 or 1988.
o Stage 1 - The Stage 1 expansions would include the
addition of approximately 10.7 MGD of capacity to
the West Boise facilities, bringing the peak hydraulic
capacity to 17 MGD. These additions would include
a new influent pump, primary and secondary clarifiers,
sludge pumps, and anaerobic primary and secondary
sludge digesters. A number of other minor additions
would also be made.
One major modification at the West Boise facility
would involve sludge digestion. Present sludge
digestion processes differ at the Lander Street
and West Boise treatment plants; existing digestion
at the Lander Street facility is anaerobic while
at the West Boise plant sludge is digested aerobically.
The CH2M Hill facilities plan analyzed three alterna-
tives at the West Boise facility: continued aerobic
digestion; continued aerobic digestion with modifica-
tions to simplify future conversion to anaerobic
digestion; and conversion to anaerobic digestion.
The comparative costs of those three alternatives
is shown in Table 4-7.
o Stage 2 - The second stage of expansion would include
construction of an equal capacity (17 MGD) treatment
plant adjacent to the present and Stage 1 expansion
facilities. That expansion should have sufficient
capacity to serve the City of Boise's wastewater
needs past the year 2000, particularly since the
Southwest community would not be contributing waste-
water to the system.
The previously mentioned Stage 1 and Stage 2 modifications
and expansion of the West Boise treatment plant facilities
are the preferred alternatives represented in the Boise
facility plan.
Sludge Management. A wide variety of the sludge processing,
transport, storage, and disposal alternatives were presented
by CH2M Hill in the Sludge Management Technical Memorandum
and in Chapter VI of the Wastewater Facilities Plan (Part 1)
(October 1980). Land application sites were evaluated on
Eagle Island and at the Idaho State Prison Farm.
32
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Table 4-7. Cost Analysis - West Boise Sludge Treatment
U)
Alternative
No. 1 - Aerobic Digestion
No. 2 - Aerobic Digestion
With Primary Clari-
fication and Flotation
Thickening (to allow
future anaerobic
digestion)
No. 3 - Anaerobic Digestion
$19,915,000
Present Worth Costs3
Capital
$17,100,000
$16,830,000
Operation and
Maintenance
$8,045,000
$8,685,000
Salvage
Value
$1,635,000
$1,760,000
Total
$23,510,000
$23,755,000
$7,885,000
$2,000,000
$25,800,000
aAII present worth costs are converted to December 1980 dollars (assumed ENR CCI = 3,414) based on a 20-year
amortization period and a 7-1/8 percent discount rate.
SOURCE: CH2M Hill 1980c.
-------
Five basic sludge management alternatives were defined
in the preliminary screening, each with a large number of
suboptions for dewatering, transport, storage and disposal.
Those alternatives were further screened to four alternatives
(Chapter VIII of Wastewater Facilities Plan, Part II) and
eventually to three composite alternatives:
o Digested (liquid) sludge truck transport to agri-
cultural use/disposal.
o Digested (liquid) sludge pipeline transport to agri-
cultural use/disposal.
o Digested sludge (dewatered form) with truck trans-
port and landfill disposal.
Costs of these three alternatives are presented in Table 4-8.
The preferred disposal site for sludge was the prison
farm because of the availability of an isolated and con-
tiguous site, the environmental constraints, presence of an
existing farming operation and the proximity to the Boise
treatment plants. Approximately 1,700 acres would be needed
for sludge application.
The majority of digested sludge in the Boise planning
area originates from the Lander Street treatment plant and
is transported by liquid transfer trucks to the agricultural
use sites located near Eagle and in the Idaho State Prison
area. Historically the Eagle area has served as the primary
agricultural use site.
Truck routes from Lander Street and West Boise treatment
plants would be the same as for existing sludge disposal
routes. A number of pipeline alternatives were defined (see
Boise Wastewater Facilities Plan Summary, September 1980).
(see Figure 4-3).
A detailed analysis of agricultural use and disposal
was presented in Chapter VII, page 61 of the wastewater
facilities plan (Part II), October 1980. Within that chapter
are discussions of guidelines and regulations for land applica-
tion of sludge, soil suitability, sludge application limits,
land requirements, methods of sludge application, and program
management.
A combined pipeline/truck sludge transportation system
offers some major advantages over separate systems. Proposed
pipeline routes would extend from the West Boise and Lander
Street treatment plants to the Gowen Field treatment plant
site. Trucks would then be used to transport the liquid
sludge 6 miles from Gowen Field to the prison area.
34
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WEST BoisE^tREATMENT PllANT
*P", PUMP STATION N0.1 •
^V r '..'"•'• " ;••"'""" /'• •'" ' •
- ^ ^v -'H.-ANDER STREET TREATMENT PLANT
PUMP STATION NQ.2
> - PUMP STATION-NO'.-?
''
V—PUMP STATION' NOTS^T
ALTERNATIVE
\_ ^
\* -A~ ^v___^-K-.y^^r,
*• ••^-a^9L- • ~—' ' -' -• ^ ,
1 t..**r"'^\7^ — • —-. - / >
i
. _. , - ' - ,^a^4^-'-,--J---A^^«-/i ^_^-::±y---^^^ v^^rfrfHT-• — -\ i, .-• ; _ _\ -;
.,-....;.. *£4
cOVVEN FIELD TfiATMENT
PUMPSTATION NO: 4
PLEAS ANTJ/ALLEY ROAD
PRISON AREA AGRICULTURAL
'LAND APPLICATION SITE STORAGE
AND PUMP STATION LOCATION - -
PRISON FARM BOUNDARY
FIGURE 4-3. SLUDGE PIPELINE ROUTING
& LAND APPLICATION SITE
35
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Table 4-8. Sludge Management Alternatives
Present Worth Estimate3
u>
Alternative
Sludge Truck Transport/
Agricultural Disposal
Sludge Pipeline Transport/
Agricultural Disposal
Dewatered Sludge/Truck
Transport/Landfill Disposal
Capital
$1,228,000
4,047,000
3,567,000
Operation and
Maintenance
$3,148,000
899,000
3,350,000
Salvage
Value
$207,000
447,000
478,000
Total
$4,169,000
4,499,000
6,439,000
aAII present worth estimates are converted to December 1980 dollars based on a 20-year amortization period
and a 7-1/8 percent discount rate.
SOURCE: CH2M Hill 1980c.
-------
Interceptor System. Two technical memoranda were prepared
by CH2M Hill which dealt with interceptor needs in the Boise
area. The two studies include Location Study - North Boise
Interceptor Technical Memorandum and the South Boise Interceptor
Route Selection Technical Memorandum. The studies focused
on three distinct needs: wastewater collection needs in
northwest Boise, routing analysis of the South Boise interceptor
through Garden City, and an analysis of need for sewer rehabi-
litation in Garden City and Boise.
North Boise Interceptor. Four alternative interceptor
alignment plans were identified in the North Boise Interceptor
Technical Memorandum to serve North Boise, an area now served
by septic tank-drainfield systems and projected as an area
for rapid development (see Figure 4-4). Conclusions of
that memo were:
o The North Boise service area would total 5,800-
6,000 acres and up to 24,300 connections, depending
on the alignment plans selected.
o The North Boise interceptor should be sized to
handle excess flows of 5.6 MGD from the existing
Glenwood pump station.
o Extensive rights-of-way would be required under all
alignment plans.
o The location of the floodway boundary of the Boise
River affects the choice of an interceptor plan and
the area likely to be serviced by the sewer.
o Estimated capital costs appear in Table 4-9.
o Operation and maintenance costs are comparable among
alternatives.
o Plan 4 offers the maximum flexibility for staged
construction.
South Boise Interceptor. The existing South Boise inter-
ceptor carries wastewater flows from the Garden City area
to the West Boise treatment plant. The proposal is to extend
the interceptor Southwest to relieve existing trunk and
interceptor lines flowing near capacity. A detailed analysis
of the routes and the advantages and disadvantages of each
was presented in the South Boise Interceptor Technical
Memorandum prepared by CH2M Hill.
The existing interceptor now terminates at the inter-
section of Field and Bradley Streets. The four alternative
routings were evaluated between the terminus at Field Street
and Main Street, approximately 11,000 feet to the southeast.
Portions of two of those alignments, River North and River
West, would be located within or fringing on the floodway
of the Boise River. In addition, the South Boise interceptor
east of Americana Boulevard would cross the Boise River to
join the future Table Rock interceptor. Two alternative
routes were evaluated from Main Street to Americana Boulevard,
a distance of approximately 4,000 feet (see Figure 4-5).
37
-------
, A; ;;
« I! ' '"
B.
-•-t. 1
10 ''-(
'V
2000
=b
FEET j
«oi>61
ALTERNATIVE
PLAN 1
PLAN 2
PLAN 3
PLAN 4
MAINS INCLUDED
A, C 8.B
A, C 8.F
A, E 8.F
A, E &B
MAINS
NOT INCLUDED
E & F
E 6 B
C & B
C & F
AREA SERVED BY
LIFT STATION
D CD
D
n
n m
\''' "' ^-•-'/" S '//'J 1
^"iv'vj - -c^* >Vf]
./^Vx^ v^'fl ^
SERVI.QE.AREA' -'> -. \ ,
. x
v BOUNDARY ', / v^ ~^j ,.
STATE STREET !.\
SERVICE AREA \.y
• *
WEST BOISE ; '"""" \
TREATMENT PLANT
'TOR. j * ,-_ •_ :4;:,:^
' ' '
fLOW'DIVERSION TO NORTH
SOUTH BOJSE
INTERCEPTOR
GLENWOOD STREET -.).' ^
/ KJMP STATION I t II
FIGURE 4-4. NORTH BOISE INTERCEPTOR ALTERNATIVES
-------
A* ' Hr
• Exist!
South
J, K Interc
Boise (
eptor
^
jibM!!*^;
-LEGEND-
— ALTERNATIVE INTERCEPTOR ROUTES
— - FUTURE INTERCEPTOR EXTENSION
T^ PRELIMINARY FLOODWAY
Ihtcn
V. „'':•' •' \ *'.','.' „:,, •
—- Lander Street « ' ;-
SSillfe;;..' WasteWater > '. '.
Treatment^ Plant „ '
ri ui 11| DCLU
», Sewer Dis
nt" ~
^
dw.i Vit.\^
» "N \- . f.
' CHINDEN>
•RiyER'WEST,
'
•RIVER jNORTH*;; „„
8T| MAIN''- ST
JAIJJVIEW
B 0' IS E
ffr^'iT' i ''• IK""1".'"'" ' >> '•
, i' ' -,; I j .r--1' "^;, ...
[l* •»"-.°f':.". INLAND EAST*
^c»:-' * •" -^sJV"1^'^'" "V "-'
^-f r^sL-^v s'"lf '-')''"' *
^^•^'^ !.^N>V^,:^.
o • (. '\ iooo-J
"
-I ' t \*
t -.-. \
"! : ^ ••- Future Extension
> South Bois^
Interceptor >
FIGURE 4-5. ALTERNATIVE SOUTH BOISE INTERCEPTOR ROUTES
-------
Table 4-9. Capital Costs of Alternative Plans -
North Boise Interceptor
Plan
1
2
3
4
Capital Costs
$3,465,000
$3,372,000
$3,450,000
$3,509,000
Capital Cost/Acre Served
$599
$583
$574
$584
SOURCE: CH2M Hill 1980c.
-------
Expansion of the South Boise interceptor would likely
be accomplished in two stages: Stage 1 - connection of the
Bench Sewer District to the interceptor and; Stage 2 - con-
nection to and east of Americana Boulevard.
No preferred alignments have yet been chosen by the
facilities engineers pending public comment and review.
Infiltration. Studies of infiltration/inflow in Garden
City and Boise indicated that rehabilitation of the sewer
system would prove cost-effective in Garden City but not
in Boise. Of the total identifiable infiltration of 3.45
MGD, as much as 1.04 MGD could be economically removed.
Flow Augmentation. Under present conditions, flows
in the Boise River during the summer months (irrigation season)
are sufficient to provide proper dilution of effluent from
the Lander Street and West Boise treatment facilities. Winter
flows (nonirrigation season), however, are significantly
less than summer flows. A program of releasing greater flows
downstream from Lucky Peak Reservoir is being developed by the
Idaho Department of Fish and Game, the Idaho Departments
of Water Resources and Health and Welfare.
The Idaho Department of Fish and Game has established
stream resource maintenance flows (SRMF) of 225 cfs in October
and November and 150 cfs during January through March. A
l-year-in-10 low river flow of 80 cfs was used by the Idaho
Department of Health and Welfare to determine treatment plant
effluent limitations at the West Boise and Lander Street
plants. Table 4-10 shows the percent of time that the Lander
Street and West Boise plants would have ammonia limitations.
Energy Requirements
Treatment Plant Expansion and Modification. In the
Boise facilities plan, CH2M Hill explored six options and
several suboptions for the utilization of methane (digester)
gas at the Lander Street treatment plant. Primary use of
the gas would be to operate raw sewage pumps and air blowers;
however, two options for generating electricity for sell-
back to the Idaho Power Company (IPCo) were also evaluated.
Digester gas generation would vary from approximately 90,000
cubic feet per day during the winter to 140,000 cubic feet
per day during the summer. The quantity of natural gas or
electrical power needed to supplement the use of digester
gas at the facilities would vary with the option. The total
average energy cost would depend on: (1) the equipment needed,
(2) whether natural gas or electricity was used to supplement
digester gas and the future projected cost of each, and (3)
the credit price allowed for electrical energy generated
and fed back to IPCo. CH2M Hill recommended that the City
of Boise choose the preferred option after negotiations for
sale of generated electricity to IPCo are finalized.
41
-------
Table 4-10. Ammonia Limitations
Treatment
Plant
Lander Street
West Boise*
Percent
Fall
15
100
of Time Ammonia
Winter
0
75
Discharge is Limited
Spring
0
25
Summer
0
75
limitations are based on projected year 2000 wastewater flows at West Boise
£t
to
SOURCE: CH2M Hill 1980c.
-------
Energy requirements for the various modification alterna-
tives at the West Boise plant are presented in Table 4-11.
The alternative of converting to anaerobic sludge digestion
was determined to be the most cost-efficient of the three
alternatives (CH2M Hill 1980c).
Sludge Management. An energy use comparison of the
various sludge transport alternatives is presented in
Table 4-12. The liquid sludge pipeline transport alternative
was determined to require the least amount of energy. In
addition to sludge transport, approximately 5,700 gallons
of diesel fuel and 52,200 kilowatt hours of electricity would
be required per year to apply sludge to agricultural land
(CH2M Hill 1980).
Project Costs
The costs of the Stage 1 project as proposed are presented
in Table 4-13. Stage 2 costs are shown in Table 4-14 and
the user costs in Table 4-14. The connection fee shown in
Table 4-15 represents a one-time charge at the time of hookup
to the sewer system.
User fees for the Boise project alternative are shown on
Table 4-15.
Eagle Water and Sewer Facilities
The existing Eagle sewage wastewater plant is considered
to be an interim treatment facility. A capacity limit equi-
valent to 790 dwelling units (population of 2,370) has been
imposed by the Idaho Department of Health and Welfare. With
the understanding that future facilities would be needed,
the Eagle Water and Sewer District (EWSD) purchased a 65-
acre site approximately 1 mile downstream from the existing
facilities.
J-U-B Engineers, Inc., prepared a facilities plan
for the EWSD (May 1980) which presented regionalization,
land application, and on-site disposal options. The
project planning and study area boundaries are shown in
Figure 4-6. The 65-acre proposed treatment plant site
Southwest of Eagle along the North Fork of the Boise River
is in an emergency flood risk zone (FEMA pers. comm. 1981)
and no official floodplain has yet been established. This
location appears to be subject to EPA floodplain and wetlands
policy analyses.
Development of the area in question may be incompatible
with the Ada County Flood Control Ordinance (Minter 1981).
43
-------
Table 4-11. Process Energy Consumption
for West Boise Alternatives
FNEP.C-Y REQUIREMENTS I horsepower)'
Alternative Mo. 1
Aerobic Dicestion
i fl 9 0 2000
Effluent Pumping 130 290
Grit Removal
Screening and Grinding 4 8
Primary Clarification
Aeration Basins 6?o 1,1 40
Secondary Clarification 3 16
Postaeration so so
Cavity Thickening
Flotation Thickening
Sludge Pumping 75 120
Aerobic Digestion 430 850
Anaerobic Digestion
Total 'Energy Required (hp) 1,417 2,50 4
Digester Gas Heating Value
(therms/year) o o
Digester Heating Require-
ments (therms /year) o o
Electrical Energy
Gen<3'r;:i'|~:ion (hp)c ° p
Net Electrical Energy
Required
o Horsepower 1/417 2(C;04
o Kilowatt-hours /MGD i,69i i', 330
Alternative No. 2
Anaerobic Dicestion
1°90
130
7
4
4
520
8
50
1
55
65
—
ioob
994
202,000
95,000
195
799
953
2COO
290
1-4
8
8
890
14
30
1
55
115
—
145b
1,620
370,000
139,000
360
1,260
920
Alternative Mo. 3
Aerobic Diaestion
With Prirrary
Clarification ar.c
Flotation Thicker.ir
1990
180
—
4
4
520
3
50
--
55
70
450
—
1, 341
0
0
0
1,341
1,601
2000
290
—
3
S
390
14
80
—
55
115
750
—
2,210
0
0
0
2,210
1,615
on average annual flow rates of 15.0 MGD in 1990 and 24.5 MGD in 2000.
j
Excludes digester sludge heating requirements.
on the following assumptions: Gas engine availability = 85 percent.
Engine generator efficiency = 25 percent.
Gas engine heat recovery efficiency = 50 percent
Boiler efficiency = 80 percent.
SOURCE: CH2M Hill October 1980c.
44
-------
Table 4-12. Energy Consumption for
Sludge Transportation Alternatives3
Item
Electrical Energy (kWh/yr)
Diesel Fuel (gal/yr)
*" h
^Total Annual Cost ($/yr)
Liquid Sludge
Liquid Sludge Liquid Sludge Dewatered Sludge Pipeline/Truck
Pipeline Transport Truck Transport Truck Transport Transport
330,300
_-
8,000
—
42,000
48,000
1,143,000
6,480
35,000
219,900
15,050
22,900
Electrical energy and diesel fuel quantities are based on average annual quantities
in the year 1990.
Annual costs are in December 1980 dollars: Electrical energy cost = $0.01915/kWh
+ $2.60/kW-month demand. Diesel fuel cost = $1.15/gal.
SOURCE: CH2MJHill October 1980c.
-------
Table 4-13. Recommended Alternatives Cost Estimate Summary3
STAGE ONE EXPANSIONS - 1983
CTl
Alternative
West Boise Expansion
Lander Street
Improvements
Sludge Pipeline
Agricultural Application
South Boise Interceptor"
North Boise Interceptor
Miscellaneous Interceptors
Flow Augmentation
TOTAL
Capital
Cost
$ 8,295,000
196,000
3,463,000
584,000
2,989,000
4,151,000
2,461,000
—
$22,139,000
Annual
O&M Cost
$585,000/yr
41,000
66,000
39,000
12,000
16,000
10,000
100,000°
$869,000
Salvage
Value
$4,125,000
118,000
1,795,000
378,000
—
—
—
—
$6,416,000
Total Present
Worth'3
$ 9,620,000
518,000
3,660,000
839,000
3,115,000
4,319,000
2,566,000
1,049,000
$25,686,000
aAII estimates are in December 1980 dollars.
'-'Present worth estimates are based on a 20-year design period and a 7-1/8 percent discount rate.
cEstimate is preliminary and may change depending upon availability of unallocated storage in Lucky Peak Reser-
voir.
Extension to Americana Boulevard (Construction may be staged with completion to intercept with Bench Sewer
District by 1 983, and remainder perhaps in Stage 2).
SOURCE: CH2M Hill 1980a.
-------
Capital
Cost
$13,700,000
2,147,000
Annual
O&M Cost
$1,135,000/yr
8,000
Salvage
Value
$6,350,000
—
Total Present
Worthb
$14,585,000
2,231,000
Table 4-14. Recommended Alternatives Cost Estimate Summary
STAGE TWO EXPANSIONS - LATE 1980's
Alternative
West Boise Expansion
Soyth Boise Interceptor0
TOTAL $15,847,000 $1,143,000 $6,350,000 $16,816,000
aAII estimates are in December 1980 dollars.
^Present worth estimates are based on a 20-year design period and a 7-1 /8 percent discount rate.
cExtensions east of Americana Boulevard.
SOURCE: CH2M Hill 1980a.
-------
Table 4-15. User Impacts3
City of Boise Alternative
User Charge
System
Treatment Plant
and Major Interceptor
Connection Fee
1980 Average
Average After Stage 1
(1983) Expansion
Average After Stage 2
(late 1980s) Expansion
$ 7.70/monthc
8.60
9.20
$165
221
224
aAII rates are given in 1980 dollars for typical domestic household.
"Actual rate for specific customer will depend on water use. Average assumes
790 cubic feet per month.
SOURCE: CH2M Hill 1980a.
48
-------
_l_
. -f—
\
>
.._
4
.
.EGEND-
— ^— EAGLE FACILITY PLAN STUDY AREA g
...... EAGLE FACILITY PLANNING AREA g
— ••— CORPORATE CITY LIMITS '
•
' '"~^,"~
i ~ "-'• ~l
,J
li
i
• , I
1
^ : . ,..-
,
^ EXISTING FACILITY SITE
| PROPOSED FACILITY SITE
r- ^— ^~ — -^ — —
1 3 '
•
' ,
C
(
•
I
1 1/2 0
MILES (APPRO)
i
.. • ' 1
i
.*•'
S
s
/
s
^ \
»> ..,i.
"i
*
t
\ '•
1 ,-1
h
1
(.)
.: :-}
. 1
1
. J
., -
-^
^',- ;
VO
__J
FIGURE 4-6. FACILITY PLANNING AREAS FOR THE EAGLE
WATER AND SEWER DISTRICT
-------
The Army Corps of Engineers has completed a ground control
survey and is currently developing new cross sections in
the area which should be completed in approximately 2 months
and which will aid in the development of the floodplain
boundaries (Fintel January 1981).
A request has been submitted to the District Engineer
in Walla Walla, Washington for floodplain information as
soon as it is available.
Flow and Waste Load Projections
Flow and waste load projections for the EWSD planning
area were based on two population scenarios - the J-U-B
projections and APA projections (Table 4-16). Flows for
each population scenario in Table 4-16 are shown both with
and without infiltration and inflow removal.
Three flow estimates were utilized for cost estimating
in the facilities plan: 1) the year 2000 APA projections
with infiltration/inflow removal (0.8874 MGD), 2) the year
2000 J-U-B projection with infiltration/inflow removal (1.1532
MGD), and 3) the year 2000 J-U-B projection without infiltration/
inflow removal (1.3082 MGD).
Treatment Alternatives
Five project alternatives were analyzed by J-U-B Engineers.
These alternatives along with the no-action alternative are
described herein.
No-Action Alternative. The no-action alternative would
be represented by the continued operation of the present
treatment system. The sand filter treatment is operating
within secondary treatment standards and would probably continue
to do so under present loading levels (population equivalent
of 2,370). While no additional hookups to the sewer system
would occur, some residential development would occur utilizing
individual subsurface disposal systems.
Alternative A - Oxidation Ditch. This alternative would
consist of pumping, pretreatment, oxidation ditch with rotating
aerators, secondary clarifiers, disinfection and sludge handling
facilities located at the new 65-acre site owned by EWSD.
Construction of the facility would be staged according to
population growth.
Effluent from the disinfection facility (chlorine contact
chamber) would be discharged through a diffuser into the
North Channel of the Boise River. Sludge from the clarifiers
would be held in an equalization basin until applied to land
by injector truck. The sludge disposal site has not yet
been determined.
50
-------
Table 4-16. Flow and Waste Load Projections -- Eagle
J-U-B PROJECTIONS
Existing Existing
Area Service* Population Change 60 gal/cap/day Rumovable I/I Non-Removable I/I Change In 250 gal/hc/day Flow Loss Total
Year Population Population Increase In K1 ow liase l''1ow Infiltration Inf 11 iral Ion Allowable I/I Allowable I/I Removable I/I Flow
1979
1985
1990
1995
2000
1979
1985
1990
1995
2000
45S1
6210
8002
10,311
13,286
4581
5125
6552
8329
10,255
2370
4552
6897
9759
13,286
2370
3467
5447
7777
10,256
—
2182
2345
2862
3527
—
1097
1980
2330
2478
--
0.1309
0.1407
0.1717
0.2117
—
0.0658
0.1188
0.1398
0.1487
0.1415
0.2724
0.4131
0.5848
0.7965
0.1415 .
0.2073
0.3261
0.4659
0.6146
0.155
0.155
0.155
0.155
0.155
APA PROJECTIONS
0.155
0.155
0.155
0.155
0.155
0.0535 :
0.0535
0.0535
0.0535
0.0535
0.0535
0.0535
0.0535
0.0535
0.0535
—
0.0606
0.0651
0.0795
0.0980
—
0.0305
0.055
0.0647
0.0691
0.0535
0.1141
0.1792
0.2587
0.3567
0.0535
0.0840
O.J390
0.2037
0.2728
0.1950
0.3865
0*5923
0.8435
1.1532
0.1950
0.2913
0.4651
0.6696
0.8874
0.35
0.5415
0.7473
0.9985
1.3082
0.35
0.4463
0.6201
0.8246
1.0424
*It is assumed that the present population in the service area not sewered, will be sewered at a rate of 55! per year or 110 persons per year.
SOURCE: J-U-B May 1980.
-------
Alternative B - Pump to West Boise Treatment Plant.
This alternative would require pretreatment (screening grit
removal and flow measurement), a pumping station and 19,000
feet of pressurized pipeline from the new treatment plant
site to the West Boise treatment plant. The pipeline would
require two river crossings.
Alternative C - Land Application by Irrigation. The
alternative of applying wastewater by slow rate disposal
method would have the following project components: pre-
treatment (screening); pumping station; aerated lagoons;
storage lagoons of either 35, 45, or 50 acres (for storage
of approximately 125 days of wastewater flows); disinfection;
application system; and 250-325 acres of land.
Alternative D - Rapid Infiltration. Rapid infiltration
was the second land disposal option evaluated. While no specific
disposal site was defined by J-U-B Engineers (1980), it was
assumed that "suitable soil and groundwater conditions exist
within reasonable distance from the treatment plant site" .
The components of the alternative would include pretreatment,
a lift station, aerated lagoon, equalization lagoons, pump
stations and rapid infiltration basins. Observation wells
would be constructed to monitor groundwater quality -
Alternative E - On-Site Disposal. This alternative
would represent a combination of on-site community septic
systems and construction of a new 0.55 MGD treatment plant
(J-U-B Engineers 1980).
Ada County presently requires a 1-acre minimum lot size
for an on-site disposal system and a well. If central water
is provided, the minimum lot size required is .5 acre. Within
the planning area, approximately 400 homes are presently
being served by individual on-site systems and another 500
units would likely be developed utilizing subsurface disposal.
Since the existing sewage treatment facilities are "at capacity"
(equivalent of 790 dwelling units), any future growth would re-
quire on-site systems or a community septic system.
The community septic system would allow connection of
a maximum of 70 dwelling units to a compartmentalized septic
tank and parallel drainfield. Septic tanks would be pumped
once every 2 years and septage disposed of at the existing
EWSD treatment facility.
Interceptor Systems
The proposed interceptor system would be common to all
alternatives except no-action and Alternative E (on-site
disposal). Sizing of the interceptor system would be based
52
-------
on a 50-year growth projection in the planning area. EPA
will fund for only a 40-year growth period. Any remaining
capacity would have to be funded locally. A proposed layout
of the interceptor system appears as the "Master Plan Map"
in the "Step 1 Facility Plan - Eagle Water and Sewer District"
prepared by J-U-B Engineers, Inc. (1980).
Energy Requirements
The energy requirements (in total horsepower) for the
five project alternatives are shown in Table 4-17. The energy
equivalent in kilowatt hours and energy costs were not pre-
sented in the facilities plan. Alternative D (rapid infil-
tration) with a 1.3082 MGD treatment capacity, the alterna-
tive preferred by EWSD, would be the most energy efficient
(J-U-B Engineers 1980).
Project Costs
The costs for all project alternatives except no-action
and Alternative E (on-site disposal) were based on the three
different sized treatment plants previously mentioned - 0.8874
MGD; 1.1532 MGD and 1,3082 MGD, and are shown in Table 4-18.
These represent present worth, total annual costs and annual
operation and maintenance.
Table 4-19 shows the capital costs of each alternative.
These represent total project costs and do no reflect any
grant assistance. "Historically, the EPA has provided 75
percent of eligible capital costs with Idaho Department of
Health and Welfare granting an additional 15 percent. The
remaining 10 percent represents the local share. Annual
operation and maintenance costs would not be grant eligible
and must be borne by the EWSD. The EWSD board has selected
rapid infiltration with discharge to the Boise River (Alter-
native D), as the preferred alternative. The proposed 20-
year plant capacity is 1.3082 MGD which is based upon the
projected service area population of 13,286. The oxidation
ditch and discharge to the Boise River (Alternative A) may
be considered the back-up alternative (Vickers pers. comm.
1981).
User fees for the Eagle project alternative were not
available for this DEIS but will be presented in the FEIS.
53
-------
Table 4-17. Primary Energy Consumption
Ul
Alternative
Treatment
Plant
Size*
Primary
Energy
Consumption
(horsepower)
Oxidation
Ditch
Pump to
West
Boise Plant
B
Land
Application
by Irrigation
C
Rapid
Infiltration
D
On-Site
Disposal
123 123123123123
75 100 105 77 127 152 105 165 170 65 95 100 80
1
2
3
0.8874 MGD
1.1532 MGD
1.3082 MGD
SOURCE: J-U-B 1980.
-------
Table 4-18. Present Worth and Annual
Operation and Maintenance Costs of
Project Alternatives - Eagle
Water and Sewer District
COST ITEM
Construction
Non-Construction
O&l-I Costs
Total Present Worth
Total Annual Cost
Annual O&M Cost
COST FOR EACH SIZE OF TREATMENT PLANT
.8874 MOD*
1,515,000
193,000
556,000
2,264,000
216,000
53,000
1.1532 MGD ^*
1,965,000
251,000
619,000
2,835,000
270,000
59,000
1.3082 MGD***
2,226,000
283,000
654,000
3,163,000
302,000
62,000
o
-P
•H
Q
o
•H
-P
ai
X
o
(U
>
-H
-P
tO
C
S-t
0)
-P
COST ITEM
Construction (Eagle W&SD)
Construction & Non-Construction
Eagle share of West Boise
Non-Construction (Eagle W&SD)
O&M (Eagle W&SD)
O&M (Eagle share of West
Boise)
Total Present Worth
Total Annual Cost
Annual O&M Cost
COST FOR EACH SIZE OF TREATMENT PLAN
.8874 MGD*
$906,000
2,250,000
115,000
298,000
470,000
4,039,000
385,000
73,000
1.1532 MGD**
$1,015,000
2,550,000
128,000
436,000
600,000
4,729,000
451,000
99,000
1.3082 MGD***
$1,074,000
2,750,000
137,000
480,000
660,000
5,101,000
486,000
109,000
0)
-H
w o
ea
Q)
> -P
-H Cfl
-P
-------
Table 4-18 (cont'd.)
Alternative D
Rapid Infiltration
COST ITEM
Construction
Non- Const ruction
O&I-I Costs
Total Present Worth
Total Annual Cost
Annual O&H Cost
COST FOR EACH SIZE OF TREATMENT PLANT
.6874 MGD* | 1.1532 MGD**
1,472,000
257,000
570,000
2,299,000
219,000
54,000
1,744,000
306,000
631,000
2,681,000
256,000
60,000
1.3082 MGD***
1,870,000
340,000
656,000
2,866,000
273,000
63,000
On-Site Disposal
COST ITEM
Construction and Non-
Construction
O&M
Total Present Worth
Total Annual Cost
Annual O&M Cost
COST FOR EACH SIZE OF TREATMENT PLANT
0.8374 MGD****
2,380,000
810,000
3,190,000
304,000
77,000
QJ
FROM: J-U-B Engineers May 1980.
The cost components for each alternative discussed are con-
struction, nonconstruction and O&M. The construction component
includes installation of all buildings and unit processes,
mobilization, site work, electrical and yard piping. The
nonconstruction cost component includes administration and
legal, engineering and inspection, miscellaneous and contingency.
The O&M cost component consists of labor to operate and maintain
the various unit processes and maintenance materials.
* Flow projections are based on APA year 2000 population
with I/I removal.
** Flow projections are based on J-U-B year 2000 population
with I/I removal.
*** J-U-B projection of total flow without I/I removal.
****The Eagle District facilities plan states that a treat-
ment plant of a minimum flow of 0.55 MGD will be required.
56
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Table 4-19. Cost Summary - Eagle
ALTERNATIVE
Capital
(1000 dollars)
Annual 0 & M
(1000 dollars)
Total
Annual Cost
(1000 dollars)
A
I**
1,708
53
216
2
2,216
59
270
3
2,509
62
302
B
1
3,271
73
385
2
3,693
99
451
3
3,961
109
486
C*
1
1,872
60
238
2
2,347
69
293
3
2,473
71
307
I)
]
1,729
54
219
2
2,050
60
256
3
2,2.10
63
273
E
1
3,584
58
342
2
3
Cn
* Cost of transmission not included.
** 1 - 0.8874 MGD; 2 - 1.1532 MGD; 3 - 1.3085 MGD,
SOURCE: J-U-B May 1980.
-------
Southwest Community
Rapid population growth in the Southwest community during
the period from 1970-1978, resulted in a number of steps
designed to provide orderly future development of the area:
o 1978 - The Board of Ada County Commissioners passed
a moratorium on additional platting in the Southwest
community -
o February 1979 - The County Commissioners adopted
the Southwest Interim Development District Ordinance
(SWIDD).
o 1979 - The Ada Planning Association (APA) initiated
preparation of the Southwest Community Wastewater
Management Plan.
During early APA planning efforts, 39 wastewater treatment
and disposal alternatives were evaluated and reduced to 10
warranting further consideration. Based on public input
and decisions regarding development density, the 10 alternatives
were narrowed to three structural alternatives and the no-
action option. Those alternatives were:
o Central wastewater collection system and treatment
at the West Boise treatment plant.
o Central wastewater collection and treatment at a
Southwest community wastewater treatment plant with
land disposal of effluent.
o Wastewater collection and treatment at community
lagoons with land disposal of effluent at separate
sites or a common site.
o No-action.
As a result of negative public reaction to costs of
the alternatives, three variations to the alternatives were
evaluated. These three variations were: Plan "A"
Urban Growth, Plan "B" Urban Reserve, and Plan "C"
Rural Lifestyle. In August 1980 the Board of Ada County
Commissioners adopted Plan C - rural lifestyle land use
plan allowing for 1 unit per 5 acres.
As a result of that decision, the use of individual
on-site surface disposal systems became the only feasible
wastewater management alternative for the Southwest community
(APA 1980) . In order to ensure some level of proper operation
and maintenance of septic systems, the Southwest Community
Wastewater Management Study set forth a number of maintenance
program alternatives.
Operation and Maintenance Program Alternatives
Three broad programs and a number of cases within each
were analyzed.
58
-------
Mandatory Operation and Maintenance Program.
Case I. With this alternative an advisory agency would
be given authority to issue renewable use permits for subsurface
systems. Inspection would be conducted every 3 years and
any needed repairs made by the homeowner. A permit fee would
be levied to finance operational costs of the program. Licensed
contractors would do the inspection, repairs and any necessary
pumping.
Case II. The Case II mandatory operation and maintenance
program would include all inspection maintenance and repairs
conducted by the public agency, with homeowners charged an
annual fee plus costs of system repairs. Easements through
private property would be necessary for maintenance and repair.
Case III. The Case III option would involve ownership,
maintenance, and repair of septic systems. An annual fee
would be levied to finance inspection and repair, with all
users charged the same fee, no matter what the needed repair
and maintenance.
Volunteer/Mandatory Operation and Maintenance Program.
This combination program would involve a volunteer or optional
mandatory program for all homeowners now on septic systems,
with mandatory participation by homeowners with failing septic
systems, and those constructing homes after implementation
of the maintenance program.
Volunteer Operation and Maintenance Program. The volunteer
program would include the establishment of a public education
program and the mailing of notices to remind homeowners to
inspect their systems.
No-Action Program. The no-action alternative would
represent a continuation of the present system of allowing
all maintenance to be the responsibility of homeowners.
Costs
The estimated annual costs of the operation and mainten-
ance programs are presented in Table 4-20.
Best Management Plan
APA identified the following factors as important in
a best management plan:
o Identification of portions of rural Ada County with
high septic system failure rates and comparison of
characteristics of such areas to determine causes
of the failures.
59
-------
Table 4-20. Monetary Cost Analysis of On-Site Management
Program Alternatives - Southwest Area
Inspection
Alternatives
Maintenance
Staff
Annual Costa to the Agency Per Community*
"Clerical "
Staff Staff Materials
Total
Mandatory
Permit Program
Mandatory O&M
Program for
Private Systems
Mandatory O&M
Program with
System Ownership
Voluntary Program
Voluntary/Mandatory
Permit Program
Groundwaler Monitoring
$Z5,000
$30,000
$ 50,000
$250,000
$2,500
$2,000
$2,000
$2,500
$40,000
$40,000
$ 2,500
$117,000
$286,000
$ 2,000
$ 6,000
$ 2,500
$ 8,000
*Assume 2,000 septic systems/community.
SOURCE: APA 1980.
-------
o Modification of design criteria established by
Central District Health Department (CDHD) to
decrease the number of septic system failures
due to identified study area characteristics.
o Establishment of a map of rural Ada County that
indicates locations of septic system failures.
The map would be continually updated to include
locations of new failures. (This is currently
being done).
o Establishment of a coordinated groundwater monitoring
program.
o Development of a public education program for
residents and commercial establishments.
o Development of a voluntary/mandatory maintenance
program.
o Establish a user fee schedule to fund the program.
The recommended plan for a maintenance program would
be for CDHD (in cooperation with IDHW and APA) to imple-
ment a combination voluntary/mandatory maintenance program
for individual on-site systems.
61
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Chapter 5
Analysis of Facility Planning
Population Projections
-------
Chapter 5
ANALYSIS OF FACILITY PLANNING
POPULATION PROJECTIONS
Introduction
Population projections prepared in conjunction with
wastewater facility planning are used to determine projected
wastewater flows. The projected flows provide the basis
for the sizing of wastewater treatment facilities. In addi-
tion, -population projections are used in environmental impact
assessments to assess potential secondary impacts of growth
accommodated by wastewater plans and to develop possible
mitigation measures.
This chapter summarizes the key issues associated with
facility planning population projections. Additional infor-
mation can be found in Appendix C.
EPA Policy on Population Projections
for Facilities Planning
EPA's policy for population projections to be used for
facilities planning is presented in Appendix A of the agency's
cost-effectiveness analysis guidelines (U. S. EPA 1978a).
The policy requires wastewater facilities plans to use popu-
lation projections developed by states or appearing in approved
208 plans, provided that state projections do not exceed
Bureau of Economic Analysis (BEA) projections by more than
5 percent, and that 208 plan projections do not exceed state
projections by more than 10 percent. New BEA projections
are currently being developed in conjunction with the federal
Office of Management and Budget (OMB). These new projections
are not expected to be completed until late 1981.
EPA Approved Population Projections
for Facilities Planning in Ada County
The state baseline population projection for facilities
planning was developed by the Bureau of Water Quality (BWQ)
and approved by EPA in January 1980. The BWQ projection
for Ada County in the year 2000 was 268,622. This projection
was subsequently revised to 289,000, and submitted to EPA,
which approved the revised projections in March 1980.
63
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In August 1978, Ada Planning Association (APA) adopted
the report Demographic and Employment Distribution (DED)
to Ye^r 2000. This report presents population and employment
projections in 5-year intervals for Ada County and for smaller
statistical areas. The DED projections were adopted as the
population projection baseline for all APA regional planning
programs, including 208 areawide waste treatment management
planning. A summary of the DED population projections is
presented in Table 5-1.
Description of Facility Planning
Population Projections
Boise Planning Area
The Boise planning area corresponds to the Boise Metro-
politan Area with the exception of the Southwest area (see
Figure 4-6). The population projections prepared by the
facilities plan consultants were based on the DED projections.
The population projection in the Boise facilities plan for
year 2000 is 212,145 (Table 4-4). This compares with 211,945
in the DED study for the year 2000.
Southwest Planning Area
A comprehensive land use plan was adopted for the South-
west planning area in August 1980. This land use plan, referred
to as Plan "C" - rural lifestyle, allows a maximum density
allowance of 1 unit per 5 acres for all new development in
areas designated "rural residential". Based on the adopted
land use plan, the population projected by APA for the year
2000 is 18,985.
As shown in Table 5-1, th6 adopted 208 (DED) projection
for the Southwest area in the year 2000 is 22,380. The dif-
ference between the DED projection and the most recent APA
projection is 3,395 persons. This additional population
projected for the Southwest planning area has been allocated
by APA to the Eagle sewer service area (Minter pers. comm.).
Eagle Planning Area
The DED projection for Eagle in the year 2000 is 10,255.
Although this projection is the adopted 208 plan projection,
APA has acknowledged that this projection is probably low
(Minter pers. comm.). With the addition of 3,395 persons
formerly allocated to the Southwest area the revised APA
projection for the Eagle planning area is approximately 13,600.
As a result, the DED projection for Eagle has been modified.
64
-------
Table 5-1. Summary of DED Planning Area
Population Projections
CTv
en
Southeast
North River
City Center
North End
Northwest
Foothills
Warm Springs
West Bench*
Central Bench
Southwest
Total Metro
Meridian
Eagle
Kuna
Rural Area**
Total Nonmetro
Total Ada County
1
11
35
2
17
5
6
3
28
36
9
120
6
2
1
8
18
139
975
,425
,650
,940
,180
,310
,725
,495
,700
,105
,080
,960
,349
,720
,308
,063
,440
,400
Additional
42
34
3
19
8
2
16
7
13
113
18
7
5
4
36
149.
,100
,300
,7L5
930
,145
,431
,079
,415
, 250
,300
,365
,801
,505
,517
,412
,235
,600
2000
53
69
6
18
24
15
5
45
43
22
234
25
10
6
12
54
289
,525
,950
,655
,110
,455
,156
,574
,115
,355
,380
,325
,150
,225
,825
,475
,675
,000
Year 2000
(-0 of Total)
18.
24.
2.
6.
8.
5.
1.
15.
15.
7.
81.
8 .
3.
2.
4 .
18.
100.
5
2
3
3
5
2
9
6
0
7
1
7
5
4
3
9
0
* Includes Garden City
**Includes Star
SOURCE: Ada Planning Association, 1978
to the Year 2000: Ada County,
Demographic
Idaho.
and Employment Distribution
-------
In the Eagle facilit5.es plan, two population projections
have been developed for the year 2000. The two projections,
13,286 and 16,019, are a result of different development
assumptions. The lower projection does not assume the develop-
ment of a major employment source while the higher projection
does reflect the development of a major employment source.
Potentially, both population projections could be increased
by 1,550 persons if a contingency planning area to the east
of Eagle were included in the projections.
Growth Accommodated by Facility Plans
Introduction
The timely phasing of wastewater facilities is an
important element in cost-effective wastewater facility
planning. Constructing facilities for the short term can
involve cost penalties associated with additional planning
efforts and financing arrangements. In contrast, the con-
struction of facilities with too much capacity commonly
involves the inefficient operation of facilities as well
as a commitment of resources which otherwise might have been
available for other public purposes. In addition, excessive
capacity in treatment facilities can be an important growth-
inducing influence. An evaluation of the staging of treat-
ment facilities and the growth accommodated in the facility
planning area is presented here.
Boise Facility Planning
Facilities planning in Boise is separated into two
stages. Stage 1 involves minor modifications at the Lander
Street treatment plant to meet effluent discharge require-
ments. No additional hydraulic capacity will be developed.
Diversion of some of the existing flow at Lander Street
to West Boise will provide capacity for some additional
growth. Based on projected flows, capacity will be reached
at the Lander Street plant sometime after the year 2000.
In addition to the Lander Street modifications, Stage 1
includes expansion of the West Boise treatment plant from
the current peak capacity of 6.3 MGD to 17 MGD. Based on
projected flows, the West Boise treatment plant will reach
its Stage 1 capacity about 1987. At that time, approximately
44,548 additional persons from 1978 estimates (Table 4-4)
will be provided sewer service. Of this total, about 81
percent or 36,070 persons will be new growth. The remaining
8,478 persons (19 percent) to be provided sewer service
are existing unsewered residents.
66
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Stage 2 involves construction of an additional 17 MGD
capacity treatment plant adjacent to the West Boise treatment
facilities. This expansion should have sufficient capacity
to serve the City of Boise's wastewater needs beyond the
year 2000. It is projected that all residents in the plan-
ning area will have sewer service by the year 2000.
Eagle Facility Planning
Facilities planning in Eagle involves a one-time con-
struction of treatment facilities. It is estimated by the
facility plan consultants (J-U-B Engineers 1980) that, as
of 1979, 2,370 persons out of a total population of 4,581
in the planning area, were provided sewer service. By the
year 2000, it is projected by J-U-B Engineers that all popu-
lation within the Eagle planning area will be provided sewer
service. Depending on which population projection is selected
for facilities planning, the sewered population at the year
2000 will range from a low of 10,256 to a high of approximately
17,500 (if all contingency areas are included).
It appears that some inconsistency exists between the
projected population to be serviced (Table 4-14) and the
serviceable population. It is recognized by J-U-B Engineers
that not all populations in the facility planning area will
be of sufficient density to warrant sewer service. However,
the total population in the facility planning area has been
used to estimate projected flows. This includes extending
sewer service to all existing populations.
Indirect Impacts of Growth
The growth projected in this study will result in a
number of indirect impacts to the environment. These impacts
are identified and discussed in the following chapter where
relevant.
Summary
EPA's policy on funding wastewater treatment facilities
requires that facility plans be consistent with population
projections used in approved areawide water quality manage-
ment plans or the projections developed by the state. In
Ada County, the DED projections are used as the baseline
for wastewater facility planning. The population projections
in the Boise facility plan appear consistent with the approved
population projections. The population projections in the
Eagle facility plan are higher than the initial 208 pro-
jections. The lower population projection in the Eagle facility
plan is, however, consistent with APA's latest population
allocation. The most recent population projections for the
Southwest area are lower than the approved 208 projections.
67
-------
The proposed two-phased construction of wastewater
facilities in Boise will require Phase 2 to be in operation
by 1987. Once operating, Phase 2 should provide treatment
capacity for Boise until sometime after the year 2000. In
Eagle, the one-time construction of wastewater facilities
should provide capacity to the year 2000. The number of
residents that will be provided sewer service in the year
2000 is uncertain at this time.
68
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Chapter 6
Land Use Conditions and Trends
-------
Chapter 6
LAND USE CONDITIONS AND TRENDS
Introduction
An important question to be addressed in this EIS is
how the existing land use conditions will change as a result
of future development. With a rapid population increase
expected in Ada County over the next 20 years, significant
land use changes will occur. Comprehensive plans have been
prepared to provide guidance for directing this growth, but
private development pressures often become an overriding influ-
ence in the absence of strong land use controls.
EPA's policy on funding wastewater treatment projects
requires that facility plans use population projections
developed by the state or those used in approved areawide
water quality management plans. The population projections
in the "Demographic and Employment Distribution (DED) report
of the Ada Planning Association (APA) (1978) serve as this
baseline forecast. The DED forecasts have been used for
all of the areawide planning undertaken by APA.
Land Use Planning Framework
The Idaho Local Planning Act of 1975 establishes the
framework for local government comprehensive planning. The
law requires all cities and counties to prepare general plans,
provides that certain elements be included in local plans,
and requires that zoning be consistent with local plans.
The State Planning Act also requires that local plans designate
"areas of city impact". The "areas of city impact" are to
be negotiated between the county and the incorporated cities.
The purpose in defining ''areas of city impact" is to identify
areas surrounding the cities where land use and other policies
are important for successful implementation of both county
and city goals (Ada County Planning Commission 1977). Figure 6-1
presents preliminary recommendations for "area of city impact"
submitted by Boise and Eagle.
In accordance with the State Planning Act, the Ada County
Comprehensive Plan was adopted in June 1977. This plan uses
the "urban service planning area" (USPA) concept. The USPA
is defined as the area which each city intends to provide
with sewer and other "urban-type" services. The USPAs within
69
-------
the study area are identified in Figure 6-1. As can be seen
from Figure 6-1, the USPA is generally smaller than the area
of city impact.
Study Area Characteristics
Wastewater Facility Planning Areas
Boise Sewer Service Area. Sewage treatment facility
planning in the Boise Metropolitan Area is the responsibility
of the City of Boise. The facility planning area (20-year
service area) is presented in Figure 3-2. The boundary of
the facility planning area generally corresponds to the
boundary established in the policy plan for the Boise Metropoli-
tan Area (Boise Planning and Zoning Department 1978). However,
the facility planning area includes Garden City and excludes
the unincorporated area south of Interstate 80 and west of
the airport. Most of this Southwest area has not been
included in the facility planning area because it is cur-
rently the focus of a separate wastewater management study
and land use plan.
The facility planning subareas and the DED population
planning subareas are shown in Figures 3-2 and 6-2, respec-
tively. The subarea boundaries do not coincide. The facility
planning subareas correspond to engineering requirements
based on gravity flow in the sewer lines. The DED population
subareas are delineated somewhat differently, based on planning
criteria. The total projected population for the Boise plan-
ning area in the year 2000 is approximately the same, 212,000
(Barker pers. comm.), under both facilities planning and
population planning scenarios.
Southwest Wastewater Management Study Planning Area.
The Southwest planning area, shown in Figure 6-1, is the
focus of a separate wastewater management study. The South-
west area includes only unincorporated lands and is approxi-
mately defined by Interstate 80 on the north, Cloverdale
Road on the west, Gowen Field on the east and the New York
Canal on the south. Although the Southwest planning area
is considered part of the Boise metropolitan area, recent
development conditions were considered significant and there-
fore warranted a separate wastewater management study.
Eagle Sewer Planning Area. The Eagle Sewer and Water
District is the agency responsible for Eagle facility plan-
ning. The facility planning boundary, changed numerous times
since its original designation, is shown in its latest version
70
-------
\
\
\
\
N
- LEGEND -
JH INCORPORATED AREA
H] URBAN SERVICE PLANNING AREA
['} AREA OF CITY IMPACT (PROPOSED)
SOURCE: ADA COUNTY PLANNING DEPARTMENT 1977
\
\
x/l
FIGURE 6-1 INCORPORATED AREAS/ URBAN SERVICE PLANNING
AREAS & "AREAS OF CITY IMPACT" IN NORTHERN ADA COUNTY
-------
1,
piiiiliiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiir.
'X,,
1. Southeast
2. North River
3. West Bench
4. Central Bench
5. Southwest
SOURCE: APA 1978a.
Figure 6-2. Boise Population Planning Area
and Subareas.
a. Northwest
b. North End
c. City Center
d. Warm Springs
e. Foothills
^lIVlTlJl'milllllflllMIIIMM IIIIIII11 Illllllllllllllllllllllllllllllliliiiiiiiiniinmn,,,,,,,,,,,,,,,,,,,,,,,,!!!!
-------
in Figure 4-6. One reason for the shift in facility planning
boundaries has been to include potential annexations south
of Boise River in the facility plan (Blake pers. comm.).
Existing Land Use
Information on existing land use in the study area is
limited. The most complete analysis of existing land use
in the Boise planning area was completed in 1970 by the Ada
Council of Governments (AGOG) (Johnson pers. comm.). More
recent information is available for the Southwest planning
area as a result of the current wastewater and comprehensive
planning efforts. For the Eagle facility planning area,
some land use information is available as a result of the
Eagle comprehensive planning effort.
Boise Planning Area. In 1975 an analysis of vacant
land in the Boise metropolitan area was undertaken to provide
land use data for the Boise comprehensive planning effort
by the Ada Council of Governments (1975c). This analysis,
although somewhat incomplete, provides the most recent land
use information for the Boise planning area.
The pattern of existing land use in the Boise planning
area is one of relatively dense concentrations of commercial
and residential uses in the central region changing to more
scattered developments in the outlying areas. Table 6-1
indicates the distribution of vacant land among zoning categories
in the incorporated and unincorporated portions of the Boise
metropolitan area.
Southwest Planning Area. The existing land use in the
Southwest planning area consists primarily of a mixture of
residential, suburban and agricultural uses. Approximately
42 percent of the 10,506 total gross acres has been subdivided
for residential use at an average gross density of 1.19 dwelling
units per acre (APA 1979a). Fifty-two percent of the Southwest
planning area is used for agricultural/grazing purposes or
is undeveloped. Industrial development in the Southwest
planning area is located primarily in the Boise airport influence
area at the eastern extreme of the area. Major commercial
uses include a community shopping center at Overland Road
and Five-Mile Road, a neighborhood shopping center at Five-
Mile Road and Lake Hazel Road, and a mixture of commercial
and industriaJ. uses at the Interstate 80/Overland Road
interchange.
Eagle Planning Area. Much of the Eagle planning area
is sparsely populated, consisting of farmland, undeveloped
open space, and floodplain. Urban land uses are centered
73
-------
Table 6-1. 1975 Vacant Land by Zoning Categories
in the Boise Metropolitan Area1
Land Use
Zoning Categories
Acreage of
Vacant Land
Percent
Vacant
Total Acreage
Net
Gross
Unincorporated Area
Agriculture
and Range
Residential-
Industrial
Cartnercial -
Office
Special
Category
SUBTOTAL
City of Boise
Residential-
Industrial -
Conmercial -
Office
Open Space -
SUBTOTAL
TOTAL ACRES
D-2
D-l
G-l
R-l
R-2
R-2MH
R-3
R-4
R-5
M-l
M-2
M-3
C-l, 2, 3
L-0
T-l
LF&A
R-1A, B
R-1C
R-2
R-3
M-l, 2, 3
C-l, 2, 3
L-0
A
15,567
3
9
953
1,632
171
223
• 548
93
616
307
128
153
0
121
0
20,524
436
985
298
131
193
330
81
255
2,709
23,233
97
43
6
67
66
36
88
51
97
58
47
100
55
0
78
0
84
37
18
17
25
9
20
29
9
17
58
16,064
7
150
1,421
2,488
470
253
1,075
96
1,062
651
128
277
0
156
52
24,350
1,189
5,432
1,771
514
2,107
1,639
284
2,833
15,769
40,119
17,145
7
152
1,505
2,624
521
269
1,166
105
1,191
727
134
331
0
161
52
26,090
1,324
6,693
2,337
575
2,308
2,044
344
2,989
18,554
44,644
includes the Southwest area but excludes Garden City.
SOURCE: ACOG 1975c.
74
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around the City of Eagle, with agricultural, rural resi-
dential' and undeveloped open space accounting for the bulk
of the land uses in the planning area. Table 6-2 presents
a summary of land use in the Eagle area.
The existing residential development pattern consists
of 3-4 lots per acre subdivisions in the city and large lots
(1-5 acre) subdivisions in the rural areas. The commercial
and industrial uses are located in the immediate vicinity
of Eagle.
Land Use Plans and Policies
The following section reviews the existing comprehensive
land use plans within each wastewater planning area and sum-
marizes the development policies.
Boise Planning Area
A policy plan for the Boise Metropolitan Area was
adopted by the Boise City Council in October 1978. This
policy plan includes the unincorporated Southwest area but
excludes the City of Garden City which has adopted its own
comprehensive plan.
In projecting a pattern for development in the Boise
Metropolitan Area, the policy plan's steering committee
suggested a development theme of centrality and compactness.
The central city area is to serve as the major employment
center for the area. Population growth is encouraged to
locate in the southeast and northwest subareas. Improved
access from these areas to the central city area is also
recommended. Infilling of vacant developable acres within
the city is especially encouraged. The city intends to slow
the rate of growth in the West Bench subarea.
The implementation of the Boise Policy Plan relies upon
an incentive/disincentive approach as opposed to a program
based upon strong growth controls. To encourage development
in the priority areas, a sewer financing formula provides
an incentive to developers through additional city participation
in funding (Stacy, pers. comm.). Additionally, improved
access in the priority areas has been provided to stimulate
growth.
In each planning subarea, target holding capacities
have been developed (Table 6-3). To achieve the holding
capacities, average dwelling units per gross acre have been
recommended. Since these density recommendations reflect
75
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Table 6-2. Land Use in the Eagle's Area of City Impact in 1977
en
Residential
Less than 10,000 square feet
More than 10,000 square feet
Five acres or more
Multifamily
Rural housing
Commercial
Industrial
Publie/Government
Institutional/School
Open Space/Parks
Vacant
More than 10,000 square feet
Five acres or more
Agriculture
TOTAL
15
741. 2
797. 5
11.6
312.0
526.2
616. 5
12,668.3
Acres
(1,877.3)
116.4
112.7
74.9
20.7
68
811.0)
16,081.0
Lots/Units
(720)
77
472
115
56
SOURCE: Eagle Planning and Zoning Commission 1979.
-------
Table 6-3. Target Holding Capacities for Boise Planning Subareas
Southeast area: -
4.5 d/u
i
North River:
West Bench:
per gross acre
- PUD's up to 7 d/u per acre except in high
density corridor
- 14 d/u per acre adjacent to floodplain
(upon review)
- 5 - 14 d/u per acre north of Highland
Street and east of Broadway
- 4.5 d/u per gross acre (outside hazard
areas)
- PUD's up to 7 d/u per gross area
- 14 units per gross acre adjacent to flood
plain open space corridor
- Warm Springs and North End to be
reinforced as predominantly single
family residential areas
- Area between 36th Street and Collister
Drive to be reinforced as predominantly
single family residential areas
- Area between Hill Road and State Street
should provide for residential densities
of 4.5 units per gross acre.
- 3.5 d/u per gross acre
- 4.5 d/u per gross acre for lands located
north of the First Bench to the Boise
River, exclusive of the floodplain
- Up to 14 d/u per acre adjacent to the
floodplain open space corridor (upon
appropriate review.)
- Larger lots and setbacks should be
encouraged on lots abutting 1-80.
SOURCE: Boise Planning and Zoning Department 1979.
77
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"average densities" for an entire planning subarea, they
provide only a general framework for guiding specific types
of development. Specific developments could result in
densities greater than those indicated in Table 6-3.
Southwest Planning Area
The 1968 Ada County Comprehensive Plan was the pre-
viously adopted plan to guide growth in the Southwest planning
area. Development policies in the plan, which called for
1-acre lot subdivisions, have not been implemented. Many
subdivisions were approved with 0.5-acre or smaller lots
and with no plans for a public sewer system. Land use-related
problems have developed as the Southwest's population has
increased seven-fold (2,000-14,000) from 1970-1979.
Concern over growth-related problems in the Southwest
area resulted in Ada County imposing a zoning and platting
moratorium on the area in 1977- The moratorium was replaced
in February 1979 by the Southwest Interim Development District
Ordinance. The interim ordinance established density limits
on various types of development while the Southwest Community
Comprehensive Plan was being prepared.
The final draft of the Southwest Community Comprehensive
Plan was submitted to the Ada County commissioners in late
spring 1980 for consideration. The residential density guide-
lines recommended in the comprehensive plan were adopted
by resolution of the commissioners. These guidelines esta-
blished a high density and a low density infill plan, depen-
dent on the outcome of the central sewer feasibility study.
The high density plan allowed four dwelling units per acre
on central sewers in the designated residential part of the
Southwest area. The low density plan allowed for two dwelling
units per acre on community wastewater systems in the resi-
dential part of the area. A density level of 1 unit per
5 acres would have been permitted on individual wastewater
systems.
In conjunction with the comprehensive plan, the Southwest
wastewater management study has been examining the options
in wastewater treatment systems for the Southwest area. At
a June workshop on wastewater alternatives, negative public
reaction to estimated costs of the alternatives was expressed.
As a result, variations of the original alternatives were
also discussed. The new alternatives reflected development
densities which ranged from 1 unit per 5 acres to 4 units
per acre. The new alternatives were discussed further at
two additional workshops held in July.
78
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As a result of the workshops on wastewater alternatives
and of public hearings on the comprehensive plan, the Board
of Ada County Commissioners adopted in August a 'land use
plan for the Southwest community- This land use plan, re-
ferred to as the "C"-rural lifestyle, contains a maximum
density allowance of 1 unit per 5 acres for all new develop-
ments in areas designated "rural residential". Although
higher densities could be permitted at some future time,
the anticipated population for the Southwest in the year
2000 is 18,985. When complete infilling has occurred, the
population is expected to increase to 20,385. The plan's
land use map is shown in Figure 6-3.
The development densities adopted in the comprehensive
plan eliminates for the present further consideration of
central or community wastewater treatment facilities for
future development in the Southwest. Individual -on-site
subsurface disposal systems will continue to be used for
wastewater management.
Eagle Planning Area
The Eagle Comprehensive Plan, adopted in 1978, was
developed by the Eagle City Council and the Eagle Planning
and Zoning Commission. In general, the Eagle planning area
is recognized as a rural, suburban bedroom community of the
Boise metropolitan area. Efforts are currently under way
to amend the Eagle Comprehensive Plan. These amendments
focus on the recently proposed Middlebrook project, which
may include an industrial park as well as residential develop-
ment.
Future Land Use
In accommodating future population growth, land use
planning efforts and market forces will cause certain develop-
ment patterns to occur within the study area. The develop-
ment objective in Ada County's Comprehensive Plan is to accom-
modate between 92-95 percent of new growth within urban
service planning areas. The following section examines
future land use conditions that would result from alternative
population projections being considered in wastewater plan-
ning. Recent development trends from APA's subdivision
monitoring program are also covered.
79
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Figure 6-3
SOUTHWEST SKETCH
PLAN
PLAN "C"
RURAL
£r, LIFESTYLE
SOURCE:
APA 1980
I [RURAL RESIDENTIAL/URBAN RESERVE
COMMUNITY SHOPPING CENTER
NEIGHBORHOOD SHOPPING CENTER
• CONVENIENCE CENTER
EXISTING SCHOOLS/PARKS
PROPOSED SCHOOLS/PARKS
EEJ RANG ELAND 80
AIRPORT INDUSTRIAL
• • « PRINCIPAL ARTERIALS
ft—« MINOR ARTERIALS
• •• COLLECTORS
A FIRE STATION
A PROPOSED FIRE STATIONS
—— SCHOOL DISTRICT BOUNDARIES
-------
Boise Planning Area
Based on population projections from the DED study pre-
pared by APA in 1978, the Boise planning area is projected
to absorb about 67 percent of the total population growth
in Ada County between the years 1975 and 2000. This projected
population will be distributed among the four planning sub-
areas (excluding the Southwest area) (see Figure 6-3). The
potential for development and the development policies for
each planning subarea are evaluated below-
The Southeast Planning Subarea. Table 6-4 indicates
that the southeast subarea was relatively undeveloped (9
percent) in 1975, but contained a proportionately high per-
centage (22 percent) of the total developable acres in the
Boise planning area. The southeast is expected to absorb
42 percent of the total additional population projected for
the Boise planning area. Recent subdivision activity for
the 30 months from mid-1977 to the end of 1979 shows a high
rate in platting activity for 1977 and 1978, with a signifi-
cant leveling off in 1979.
The policy plan for the Boise Metropolitan Area (Boise
Planning and Zoning Department 1978) identifies the southeast
subarea as a priority development area. The city has pro-
posed certain incentives to promote the development (i.e.,
utility connections, high densities) and desirability (i.e.,
improved access, public services) of the area. An additional
population of 42,100 between the year 1975 and 2000 has been
projected by APA at an "average density" of 4.0 dwellings
per acre (APA 1978a).
The North River Planning Subarea. The North River subarea
is the largest planning subarea in terms of population and
acres in the Boise planning area. It contains almost half
(48 percent) of the developable acres in the Boise planning
area and is projected to absorb 34 percent of the projected
1975 to 2000 population increase.
The North River planning subarea is delineated into
five sections (see Figure 6-2). The northwest section has
been designated as a priority development area, with Bogart
Lane having been classified as a reserve area for possible
urban expansion. In the foothill section, development res-
trictions have been imposed due to potentially hazardous soil-
related conditions.
Recent development activity as evidenced by subdivision
platting indicates that the North River subarea has been
steadily increasing its share of total platted lots in Ada
County (APA 1979b). In the 6-month period ending in
81
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Table 6-4. Allocation of Population and Land by Population Planning
Subareas for the Boise Planning Area
CO
to
Southeast Planning Subarea
North River Planning Subarea
West Bench Planning Subarea
Central Bench Planning Subarea
Percent of Total*
Population Acres
Allocated (Percent
1975-2000 of Total)
42% 8,494
(19%)
34% 18,675
(42%)
16% 11,182
(25%)
7% 6,198
(14%)
Vacant
Acres
(Percent
of Total)
6,642
(28%)
10,701
(45%)
5,131
(22%)
1,062
(5%)
Developable Developed
Acres Acres
(Percent (Percent
of Total) of Total)
4,262
(22%)
9,591
(48%)
4,934
(25%)
986
(5%)
1,852
(9%)
7,974
(38%)
6,051
(29%)
5,136
(24%)
*Total does not add up to 100% due to rounding.
SOURCE: APA 1978.
-------
December 1977, the North River subarea accounted for only
3 percent of the total platted land in Ada County. In the
6-month period ending in December 1979, platted lands in
the North River subarea had increased to 14 percent of the
Ada County total.
The West Bench Planning Subarea. The West Bench planning
subarea contained 25 percent of the developable acres in
1975. It is'projected to absorb 16 percent of the projected
1975 to 2000 population growth in the Boise planning area
(Table 6-4). The policies to minimize population growth in
the West Bench planning subarea are a result of efforts to
balance growth and to lessen adverse land use impacts in
the area.
Recent development activity over a 30-month period from
July 1977 to December 1979 reveals that subdivision platting
has been extremely high (around 20 percent of the total plats
in Ada County). This high level of activity most likely
reflects recent infill of platted land. The current high
level of subdivision activity in the West Bench area is
expected to level off as the policies encouraging growth
elsewhere are implemented.
The Central Bench Subarea. The Central Bench subarea
is the most densely developed of the planning subareas. Although
it contains 24 percent of the Boise planning area's developed
acres, this planning subarea contains only 14 percent of
the total acres. With 5 percent of the developable acres
in the Boise planning area, the Central Bench subarea is
expected to absorb 7 percent of the additional population
(1975-2000).
Recent development activity indicates that the Central
Bench subarea has maintained a relatively constant rate of
the total platting activity in Ada County, around 6 percent
of the total platted lands. In general, the Central Bench
planning subarea contains a small percentage of developable
acres but can be expected to build-out on this remaining
acreage.
Summary. Development in the Boise planning area is
being directed to the Northwest and Southeast subareas. Although
areas of concern (i.e., foothills, floodplains, airport influence
areas, etc.) have been addressed in the Boise Policy Plan,
implementation of the policy guidelines is uncertain. If
the development policies are not strictly followed, the emerging
pattern of development could be quite different from that
described in this section.
83
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Southwest Planning Area
In response to anticipated adverse impacts associated with
rapid development in the Southwest planning area, the South-
west Community Comprehensive Plan study was initiated. This
planning effort was designed to determine a development density
which would ensure a balanced approach to growth accommodation.
Development of a comprehensive plan has proceeded concurrently
with the Southwest community wastewater management study
(APA 1980). Initially, these planning activities considered
two basic development patterns for the Southwest area. The
total acreage developed would have been similar under the
two scenarios, but would involve different residential densi-
ties. These two alternative development patterns were termed
the "sewer option" and the "urban reserve option".
Under the "sewer option", the northern 5,700 acres of
the Southwest area would be served by the phased construction
of a new central sewerage system. In general, density allow-
ances in the northern portion of the area from 1980-1990
would be two units per acre; this would increase to four
units per acre from 1990-2000. The southern portion of the
Southwest area would continue to grow during the 20-year
period at 1 unit per 5 acres. The population projected in
2000 under the "sewer option" was 29,380.
Under the "urban reserve option" development would be
guided by land use and wastewater management policies as
defined in the Southwest Interim Development District Ordi-
nances and the Southwest Community Comprehensive Plan. In
general, these policies would allow development to occur
at a maximum of 2 units per acre in the area designated
as residential. One unit per 5 acres would be the maximum
allowed density in the area designated as "rural residential".
This density level would allow a population of 22,400 in
the year 2000.
As previously discussed, a comprehensive plan was recently
adopted which permits a maximum of 1 unit per 5 acres for
new development in the Southwest. This land use plan, referred
to as Plan "C" - rural lifestyle, would essentially maintain
the existing rural lifestyle which characterizes much of
the area. Future development at higher densities, however,
was not precluded by adoption of the comprehensive plan.
Provisions to resubdivide into higher densities could be
implemented at some future date, if coupled with sewer
service and other public services. In the meantime, the
5-acre minimum lot size requirement can be expected to signi-
ficantly reduce new development in the Southwest area (APA
1980) .
84
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Based on current population projections for the Southwest
area in the year 2000 (18,985 persons [APA 1980]), the growth
increase over the 21-year period from 1979-2000 is 4,985
persons. Although this projected population increase is
relatively small, the impact on land use could be significant
since development densities are limited to 1 unit per 5 acres.
Assuming a density of 3 persons per dwelling unit, the projected
increase of 4,985 persons from 1979-2000 would result in
1,661 new residences. At 1 unit per 5 acres, at least 8,308
acres would be required to accommodate the project growth.
Total acreage in the Southwest area is approximately 10,500
acres (Blake pers. comm.).
The type of development which will likely occur as a
result of the adopted density limitations is "ranchette-
type" developments. This will result in a sprawl pattern
of development which incurs additional costs to provide most
public services. In addition, significant capital invest-
ment will be required to extend utility services.
Eagle Planning Area. Much uncertainty exists concerning
the future land use conditions in the Eagle planning area.
Future land use is described here for three alternative develop-
ment scenarios. The first alternative assumes a continuation
of the present development pattern for a population total
at the year 2000 of 10,255 (APA 1978). Under this alterna-
tive, development along the Highway 44 corridor between Eagle
and Boise would continue to occur. Although most of the
development is expected to be clustered within the City of
Eagle, much of the remaining development would be distributed
along major roads such as Eagle Road, Floating Feather Road,
and Beacon Light Road. The residential densities for this
alternative are defined in the current Eagle Comprehensive
Plan (Eagle Planning and Zoning Commission 1978); these are
five units per acre in the core area and three units per
acre outside of the core area.
The second alternative development scenario assumes
the expansion of Eagle south of the Boise River to include
an area currently proposed for development. Assuming an
entirely residential development, the year 2000 population
is projected to be 13,286. A third development alternative
assumes that the area south of Boise River would be developed
using approximately 290 acres for residential development
and 240 acres for an industrial park. If this development
mix of residential and industrial park is approved, a popu-
lation of approximately 16,000 is projected for the year
2000.
85
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While it is not clear to what extent demographic patterns
would be altered if the area south of Boise River is annexed
and developed, it appears that population and employment
patterns, both for the Eagle planning area and other parts
of the county, would be affected.
Summary
In conclusion, determination of the future Land use
conditions for all three planning areas is highly dependent
upon the success in implementing and maintaining development
policies. In the Boise planning area, future- land use condi-
tions appear somewhat predictable since the development
pattern is already limited by the structure of existing develop-
ment. The land use outlook for the Southwest planning area
depends on the county's ability to implement the provisions
of the Southwest community plan. The future land use pattern
in the Eagle planning area envisioned in Eagle's recently
adopted general plan may be greatly modified as a result
of expansion south of Boise River; the nature of this change
cannot be determined until development proposals for the
area are finalized.
86
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Chapter 7
Air Quality
-------
Chapter 7
AIR QUALITY
Introduction
Terminology
Any discussion of air pollution issues requires an under-
standing of terms and phrases which have a technical meaning
in the context of air pollution discussions. It is especially
important to understand the distinction between air pollutant
emissions and ambient air quality. The term "pollutant
emissions" refers to the amount (usually stated as a weight)
of one or more specific compounds introduced into the atmos-
phere by a given source or group of sources. The term
"ambient air quality" refers to the atmospheric concentration
(anununt in a specified volume of air) of a specific compound
actually experienced at a particular geographic location
(which may be well removed from the location of relevant
emission sources). Measured ambient air quality levels are
determined by: the location .of emission sources; the types
and amounts of pollutants emitted; the physical processes
(meteorology) affecting the distribution, dilution, and
removal of these pollutants from the area of concern; and
chemical reactions which transform pollutant emissions into
other chemical substances and sometimes generate other pollu-
tants from normal atmospheric constituents.
Air pollutants are often characterized as being "primary"
or "secondary" pollutants. Primary pollutants are those
which are emitted directly into the atmosphere (e.g., carbon
monoxide, nitric oxide, hydrogen sulfide, sulfur dioxide,
many types of particulates, and many types of organic compounds,
etc). Secondary pollutants are those which are formed through
chemical reactions in the atmosphere (e.g., ozone, nitrogen
dioxide, sulfuric acid, sulfate and nitrate particulates,
etc.). These chemical reactions usually involve primary
pollutants, normal constituents of the atmosphere, and some-
times other secondary pollutants.
The distinction between primary and secondary pollutants
is more than a matter of semantics; important air quality
management implications are also involved. The ambient con-
centration of primary pollutants depends on the concentration
and strength of emission sources, and the degree to which
87
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emissions are dispersed or removed from the atmosphere between
the emission source and the ambient air quality monitoring
instrument. Thus, air quality problems involving primary
pollutants can usually be traced to a single pollutant source
(or concentrated group of sources) emitting large quantities
of the pollutant of concern. When an air quality problem
involves a secondary pollutant, however, the relationship
of emission sources to air quality problems becomes much
more complicated. Because secondary pollutants are not emitted
directly into the atmosphere, observed ambient concentrations
may not show much correlation with the concentration of pre-
cursor emission sources. The time factor involved in the
chemical reactions producing secondary pollutants allows
emissions from numerous sources to become dispersed and mixed
together. As a result, the observed ambient pollutant Con-
centrations are due more to the cumulative areawide mass
emissions of precursors than to the spatial concentration
of emission sources.
Meteorological Factors
Meteorological factors are important to consider from
several perspectives when evaluating air quality issues.
Factors such as temperature, humidity, and the intensity
and duration of sunlight play important roles in governing
the nature and rate of chemical reactions in the atmosphere.
Atmospheric turbulence, wind patterns and vertical temperature
gradients are important factors governing the distribution
and dispersion of pollutants. Atmospheric turbulence, wind
patterns and precipitation processes affect the rate at which
pollutants are removed from the atmosphere.
Topographic Effects. Topographic conditions exert con-
siderable influence over local meteorological conditions.
Surface winds are deflected and channeled by terrain features,
resulting in air flow patterns at ground level which may
be quite different from the prevailing winds at higher
altitudes. In areas of rugged terrain, slope and exposure
greatly influence microclimatic conditions. In such areas,
daytime heating of mountain slopes can lead to a gentle upslope
breeze. Conversely, nighttime radiational cooling of the
slope will produce a layer of cold air next to the ground,
resulting in a downslope drainage flow of cold air. These
localized upslope and downslope flows are sometimes called
mountain and valley winds.
Atmospheric Stability and Temperature Inversions. The
topic of atmospheric stability centers on processes which
88
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produce or resist vertical motions in the atmosphere. On
a microscale level,, vertical motions are predominantly a
result of mechanical turbulence due to wind flow across non-
uniform surface features. On a larger scale, vertical tempera-
ture differences within an air .column become the major con-
sideration. Because atmospheric pressure decreases with
altitude, there is also a natural tendency in the lower
atmosphere for temperature to decrease with altitude.
An air parcel can be heated by contact with a warmer
surface, absorption of sunlight or infrared radiation, or
through heat released by condensation of liquids within the
air mass. If the air near ground level is heated sufficiently,
a pocket or "cell" of warmed air will expand and rise, being
displaced by cooler, denser air from above. As it rises,
the cell of warm air will expand further due to decreasing
atmospheric pressure, causing the temperature of the air
cell to drop. The air cell will continue to rise, expand
in volume, and cool until it reaches an altitude where it
is at the same temperature and pressure as surrounding air
masses. This rising of warmed air and replacement of cooler
air from above results in vertical mixing of the air column.
This type of vertical instability occurs when air at ground
level is significantly warmer than the air aloft. If the
air at ground level is only a little warmer than the air
aloft, air parcels will neither rise nor sink, and "neutral
stability" conditions will exist.
Stable atmospheric conditions occur when the air near
ground level has essentially the same temperature as the
air aloft, or when the air aloft is actually warmer than the
air at ground level. This latter situation, where air
temperature actually increases with altitude, is called a
temperature inversion.
Figure 7-1 illustrates the relationship between vertical
temperature changes and the various atmospheric stability
conditions discussed above. As can be seen from this figure,
unstable conditions are more sensitive to changes in vertical
temperature gradients than are stable conditions.
Temperature inversions can form under a wide variety
of circumstances. Radiation inversions often form during
clear nights when the land surface cools faster than the
air above it. Air at ground level thus cools more rapidly
than air at higher altitudes, creating a temperature in-
version. In mountainous areas, downslope movements of dense,
cold air from higher elevations can create an inversion
condition in valley areas. An influx of a shallow layer
of cold air under a larger warm air mass will also create
an inversion condition. A warm air mass moving into an area
89
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FIGURE 7-1
RELATIONSHIP BETWEEN ATMOSPHERIC STABILITY
AND INVERSION CONDITIONS
500 -
400
CO
cc.
o
cc
o
CD
-------
above a cold air mass at ground level can also create inversion
conditions. A subsidence inversion forms when a large mass
of air within a stagnant high pressure system sinks down
over an area and is warmed by compression to a temperature
higher than that of the surface air mass. This occurs because,
as air from the center of a high pressure area spreads outward,
it is replaced by 'a sinking air mass from above.
Radiation inversions and inversions formed by cold air
drainage usually occur at or near ground level. Subsidence
inversions usually form at higher altitudes above the ground.
Both surface and elevated inversion layers may be present
simultaneously. Surface inversions tend to break with normal
daytime heating of the land while inversions aloft tend to
be more persistent.
It should also be noted that cloud cover reduces daytime
heating of the ground and traps nighttime heat radiation
from the ground, thus favoring neutral stability conditions.
Strong winds result in turbulent mixing of the lower atmosphere,
thus suppressing both the heating and cooling of surface
air parcels; this again promotes neutral stability conditions
(though adding mechanical turbulence).
The presence of snow cover or frozen ground conditions
can greatly influence the persistence of ground level inver-
sions. Snow cover reflects sunlight, resulting in reduced
heating of land surfaces. Frozen ground will absorb sunlight
and warm when temperatures are below freezing. As the ground
temperature approaches 32°F, the heat energy in sunlight
will be expended in thawing the soil with little actual change
in soil temperature. Thus, both snow cover and frozen ground
conditions can inhibit the processes which weaken and destroy
ground level inversions.
Existing Air Quality Problems
Ambient air quality monitoring in the Boise area has
focused on carbon monoxide (CO). The Idaho Air Quality
Bureau operates two permanent CO monitoring stations which
provide continuous monitoring data. The Idaho Transportation
Department operates a third continuous monitoring station
at its State Street offices. There have also been three
special CO monitoring programs which provide additional
data on the nature and extent of CO problems. There has
been a limited amount of monitoring for other pollutants.
Since data are limited for other pollutants, the focus of
this chapter will be on CO.
91
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EPA has established two sets of ambient air quality
standards for CO. The standard for 1-hour exposures is
currently 35 ppm (parts per million), to be exceeded no more
than once per year at any air quality monitoring site. An
additional standard has been set for 8-hour exposures. This
standard (9 ppm averaged over a consecutive 8-hour period)
is also to be exceeded no more than once per year. In
practice, the 8-hour standard is more stringent than the
current 1-hour standard. EPA has proposed changing the
1-hour standard to 25 ppm, but no final action has yet
been taken.
Summary
Available monitoring data from several sources indicate
that the Boise area experiences a geographically extensive
pattern of high CO levels. These high CO levels are concen-
trated primarily along major traffic corridors. Under appro-
priate meteorological conditions (light winds and low level
temperature inversions), air masses containing high CO levels
can be transported more or less intact over distances of
up to 1 mile. Thus, much of the Boise area is susceptible
to episodes of high CO levels which originate primarily from
major roadway corridors.
Episodes of high CO levels show a rather strong seasonal
pattern, with most episodes occurring during the winter
(November-February). There have, however, been instances
of 8-hour CO levels above the federal standard during every
month of the year and almost every possible 8-hour period
of the day. The seasonality, frequency, and magnitude of
CO episodes show significant yearly variation.
The valley and bench areas in Boise both experience
severe CO episodes. The hourly patterns of high CO episodes
in these two areas are rather distinctive. While these pat-
terns could be produced in several ways, the simplest expla-
nation centers around differences in the pattern of vehicle
activity. Vehicle emissions are clearly the source of CO
problems in the Boise area. The frequency and magnitude of
CO episodes, however, are strongly influenced by the meteoro-
logical and topographic conditions of the area.
Appendix G provides a discussion of CO data collected
by the various special studies and the permanent monitoring
stations. These various data sources are briefly discussed
below.
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ESL/CH2M Hill Study
The first significant air quality monitoring program
in the Boise area was conducted from January through May
1974. Monitoring site locations are shown in Figure 7-2.
In addition to these monitoring stations, short-term bag
sampling was conducted at street intersections near four
of the five fixed stations. The federal 8-hour CO standard
was exceeded at three of the five sites. The Eastman Building
site regularly recorded monthly peak 8-hour average CO values
of 12-20 ppm. None of the short-term bag sampling identified
any violation of the federal 1-hour standard.
This study concluded that CO problems existed in the
downtown Boise area, and at some more outlying areas. It
was also concluded that areas on the first bench or higher
locations generally comply with the federal CO standards.
EPA Study
EPA sponsored a special CO monitoring study during late
1977. Four-hour bag samples were collected twice a day on
weekdays between 10:00 a.m. and 6:00 p.m. Monitoring sites
used in this study are shown in Figure 7-3. Site 13 was
located adjacent to the Idaho Air, Quality Bureau's downtown
monitoring station. The peak 8-hour CO level measured during
this study was 17.2 ppm at site 32.
This study concluded that the state's permanent monitoring
station on Ninth Street is generally representative of CO
concentrations in downtown Boise, although the station under-
estimated the magnitude and frequency of elevated CO levels.
For example, the permanent station recorded exceedences of
the federal 8-hour CO standard on 47 percent of the study
days. This is in contrast to one or more of the study sites
recording exceedences on 95 percent of the days. The state's
downtown monitoring station recorded an 8-hour CO level of
13.7 ppm at the time that EPA's site 32 station recorded
the 17.2 ppm average noted above. On 19 of the 20 days in
the study at least one of the EPA study sites had a 10:00 a.m.
to 6:00 p.m. average CO level greater than the simultaneous
reading at the state's Ninth Street monitoring station.
Idaho Air Quality Bureau Study
In an attempt to better characterize the spatial extent
of the carbon monoxide problem in Boise, the Idaho Air Quality
Bureau conducted a special monitoring program between November 7,
1977 and March 6, 1978. The major purpose of the study was
to assess carbon monoxide levels in areas outside the central
business district of Boise. The bench areas southwest of
93
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VD
FIGURE 7-2. MONITORING SITES
USED IN THE ESL / CH2M HILL
STUDY
-LEGEND-
IT] FIRE STATION No.8
H] FIRE STATION No. 6
[T) ITD BUILDING
H EASTMAN BUILDING
H CH2M HILL BUILDING
-ft)-SITES RECORDING AT LEAST 1
" 8 HOUR CO VALUE > 9ppm
SOURCE: REDRAWN FROM ESL INCORPORATED
AND CH2M HILL, 1974
L, ^*
V
-------
_^ [_
23 I SITES USED FOR 20 DAYS
33A) SITES USED FOR FIRST TEN DAYS ONLY
f^\ SITES RECORDING AT LEAST ONE 10 AM - 6 PM
AVERAGE CO LEVEL GREATER THAN 9ppm
FIGURE 7-3. MONITORING SITES USED DURING
THE EPA CARBON MONOXIDE STUDY
-------
the Boise River received special attention. Three portable
CO monitors were used to collect data for 1-week time periods
at a total of 46 sites. Traffic counts were made at most
of the monitoring sites. Monitoring sites were classified
by location as either valley or bench sites, and by proximity
to major roadways as either traffic corridor or neighborhood
sites.
Figure 7-4 shows the locations of the 46 monitoring
sites. Despite the limited duration of monitoring at any
one site, 20 of the 46 sites recorded at least one 8-hour
average CO value above the 9 ppm standard. The highest 8-
hour CO values were monitored at traffic corridor sites on
the bench. Eight of 10 stations reporting peak 8-hour CO
values of 12 ppm or more were bench sites. The highest 8-
hour CO value recorded during the study (25.0 ppm) occurred
on a day when the permanent downtown monitoring station did
not record any violations of the 8-hour standard. This value
also exceeded the peak 8-hour CO value recorded by the Ninth
Street monitoring station during all of 1978. The only neighbor-
hood site to record an 8-hour CO value above 9 ppm recorded
an 11.1 ppm 8-hour average at this time.
The results of the Air Quality Bureau study clearly
indicated that high CO levels occurred near major traffic
arteries on the bench as well as in valley areas. The results
also confirmed the observations of the EPA study regarding
the occurrence of high CO levels even when the Ninth Street
monitoring station shows no violation of the federal 8-hour
standard.
Permanent Monitoring Station Data
The Idaho Air Quality Bureau currently operates two
permanent monitoring stations in Boise. The downtown
station (at the Odd Fellows Hall on Ninth Street, south-
west of Idaho Street) has operated since July 1975. The
Orchard Street station (south of Highway 55) has operated
since May 1978.
Monitoring data from these two stations are presented
in Appendix G. The downtown station has recorded 8-hour
CO values as high as 20.4 ppm (in 1978) and 1-hour CO values
as high as 40.9 ppm (1977). Violations of the federal 8-
hour CO standard have been recorded on as many as 87 days
during a single year (1976) at the downtown station. Peak
CO values at the Orchard site are much lower (8-hour average
of 12.8 ppm and 1-hour average of 29.5 ppm, both in 1979).
Complete data for 1980 have not yet been reviewed.
96
-------
vo
FIGURE 7-4. MONITORING SITES
USED DURING THE IDAHO AIR
QUALITY BUREAU CO STUDY
-LEGEND-
IS BENCH SITE
© VALLEY SITE
-<4>OR-(i> SITES RECORDING AT LEAST
1 8 HOUR CO VALUE > 9ppn
SOURCE: REDRAWN FROM IDAHO AtR
QUALITY BUREAU,1978
-N
\ 7\
V
-------
The hourly pattern of CO levels in the downtown area
is illustrated by Figure 7-5. Both the morning and evening
commute periods are evident from the monitoring data. The
evening commute period shows a higher average CO value than
the morning commute period. This is partially a reflection
of the station location (near the intersection of two "out-
bound" streets). A more significant factor, however, involves
the operating condition of cars in the location traffic flows.
The evening commute period involves cars which are generally
in a "cold" operating mode (with high emission rates). A
significant portion of the morning commute traffic will be
in a warmed-up operating mode (with lower emission rates).
An interesting contrast to the downtown station is pro-
vided by the Orchard Street station. The pattern of hourly
CO levels at this site (Figure 7-6) shows a predominance
of the morning commute pattern. A major factor here, as
at the downtown site, is the cold vs. warmed-up condition
of vehicles in the local traffic flow.
The downtown and Orchard monitoring stations show dis-
tinctive patterns in the occurrence of 8-hour CO values
exceeding the 9 ppm standard. Data from the downtown station
are summarized in Figure 7-7. Most episodes occur during
time periods which include the mid-afternoon and early evening
periods. The Orchard site (Figure 7-8) shows a pattern which
has two distinct periods of episode conditions. High CO
levels tend to occur during the morning to early afternoon
period and again during the evening to late nighttime period.
To a large extent, this is probably a reflection of shopping
and other nonwork trips.
Idaho Transportation Department Monitoring Data
The Idaho Transportation Department operates a continuous
CO monitor at its laboratory building off of State Street.
Data have been collected since December 1975. No statistical
data summaries are available. A preliminary review of the
hourly data indicate five episodes of 8-hour CO levels above
the federal standard (1 in 1976 and 4 in 1979). The highest
8-hour CO value appears to be a 10.6 ppm average on November 16
1979 (7:00 a.m. to 3:00 p.m.). All of these episodes occurred
during the early morning to early afternoon time period.
The highest 1-hour CO level reported was 30 ppm on February 17,
1976 at 8:00 a.m. to 9:00 a.m. The pattern of hourly CO
levels strongly suggests the influence of local vehicle
parking activities plus some pollutant transport from other
areas.
98
-------
FIGURE 7-5
AVERAGE WINTER CARBON MONOXIDE LEVELS
AT THE BOISE ODD FELLOWS HALL
MONITORING STATION
o:
UJ
>
-------
FIGURE 7-6
AVERAGE WINTER CARBON MONOXIDE LEVELS
AT THE CENTRAL DISTRICT HEALTH
DEPARTMENT MONITORING STATION
7.0
6.5-
6.0-
Q-
O.
5.0-
4.5-
O
O
LU
CS
-------
JULY-DECEMBER 1975
181 TOTAL OCCURRENCES
FIGURE 7-7
TIME PERIODS WITH 8-HOUR CO LEVELS > 9.0 PPM
AT THE BOISE ODD FELLOWS HALL MONITORING STATION
1976
618 TOTAL OCCURRENCES
l»«M^-«a»"g«»*" *•* «•»•»•
I s s i ? | : 5 = s ; s s : s s t ; ; | ; l
i a • 5 I S " * •""•»"«*JSa»»"
1977
374 TOTAL OCCURRENCES
8-HOUR TINE PERIOD
8-HOUR TIKE PERIOD
::?:|li:s;:ssssilM
8-HOUR TIME PERIOD
1978
374 TOTAL OCCURRENCES
1979
267 TOTAL OCCURRENCES
Tfei
SJi,
Si,
NOTE- VALUES ABOVE
is=;s:;i;
8-HOUR TIHE PERIOD
FfiEOUEKCr GRAPH INDICATE NUUBER Of OCCUMENCES fOR SPECIFIED THE PERIOD
= I? •:
6-HOUB TIME PERIOD
1976-1979 COMPOSITE
1,834 TOTAL OCCURRENCES
-HOUR TIME PERIOD
DATA SOURCE HOUnLY CO DATA FnOM IOAMO Alii OUALITr BUREAU
-------
FIGURE 7-8
TIME PERIODS WITH 8-HOUR CO LEVELS >9.0 PPM
AT CENTRAL DISTRICT HEALTH
DEPARTMENT MONITORING STATION
MAY- DECEMBER 1978
20 OCCURRENCES
1979
92 OCCURRENCES
8 - HOUR TIME PERIOD
8-HOUR TIME PERIOD
II
ill
1978-1979 COMPOSITE
112 OCCURRENCES
lia
Ii
II
^
g?
^
: :
FW SJEC'f.t; Tine
J-KOUR rmE PERIOD
«OIC«TE tuWER OF OCCU««E»as
-102-
-------
Air Quality Management Considerations
Institutional Framework
Federal and state activities related to air quality
have been authorized by several pieces of legislation, the
most important of which are the 1970 and 1977 amendments
to the Clean Air Act. The 1970 Clean Air Act amendments
set the basic structure for federal and state air pollution
control programs. This basic structure has been retained
under the 1977 Clean Air Act amendments.
The 1970 Clean Air Act amendments required each state
to develop and adopt a plan (implementation plan) to achieve,
maintain and enforce the national primary and secondary ambient
air quality standards in all portions of the state. The
1970 amendments further required that these implementation
plans provide the means for achieving and maintaining all
national primary standards by July 1975 and all national
secondary standards "within a reasonable time". EPA was
granted the authority to approve or disapprove these plans,
and to promulgate an acceptable plan if all or a portion
of the submitted plan was disapproved. EPA was also given
the authority to grant time extensions of up to 2 years for
the attainment of a national primary ambient air quality
standard in any particular air quality control region.
The 1977 Clean Air Act amendments recognized the fact
that most of the major urban regions of the country failed
to attain the national primary air quality standards within
the deadlines set by the 1970 Clean Air Act amendments. The
new amendments required the states and EPA to identify areas
which meet all federal air quality standards; areas which
exceed any of the federal standards; and areas where adequate
ambient air quality monitoring data are lacking. Ada County
has been designated a "nonattainment area" for carbon monoxide,
and as either an "attainment area" or an "unclassifiable
area" (areas where data are nonexistent or insufficient to
determine attainment or nonattainment status) for other air
pollutants.
The 1977 amendments to the Clean Air Act establish
numerous criteria for determining the adequacy of state
implementation plans. Some of the more significant of these
include the following requirements:
o The implementation plan must include special pro-
visions for areas designated as nonattainment areas.
Plans for nonattainment areas must provide a means
of achieving the federal primary standards as ex-
peditiously as possible, but not later than December 31,
1982.
103
-------
o If an area is designated as a nonattainment area
with respect to ozone or carbon monoxide, EPA can
extend the deadline for achieving the federal air
quality standard by up to 5 years (to December 31,
1987) provided a number of specified conditions are
met.
o The implementation plan must include schedules and
timetables for implementing emission limitations,
transportation controls, air quality maintenance
plans, preconstruction review of direct sources of
pollution, and other measures necessary to ensure
attainment and maintenance of the federal primary
and secondary air quality standards.
o State implementation plans for nonattainment areas
must provide for installation of "reasonably available
control technology" on existing stationary sources.
o Plans for nonattainment areas must provide a means
of achieving annual incremental reductions in the
emissions of relevant pollutants so as to attain
the federal air quality standards by the target date
identified in the plan ("reasonable further progress"
requirement).
o Plans for nonattainment areas must expressly identify
and quantify pollutant emissions which will be allowed
to result from the construction and operation of
major new or modified stationary sources in the non-
attainment area.
o The implementation plan must prohibit construction
or modification of major stationary sources in non-
attainment areas after June 30, 1979 if the state
has failed to submit to EPA acceptable implementation
plan revisions pertaining to that nonattainment area.
The 1977 Clean Air Act amendments indicate that implemen-
tation plan provisions for ozone and carbon monoxide nonattain-
ment areas should be prepared by an appropriate organization
of local government officials, as designated by the state.
The Ada Planning Association (APA) has been designated as
the lead agency for developing air quality management programs
for Ada County-
The 1977 Clean Air Act amendments contain several pro-
visions regarding federal permit activities or financial
assistance programs. These provisions can be summarized
as follows:
104
-------
o After July 1, 1979 EPA is prohibited from awarding
any grants authorized under the Clean Air Act, except
for air quality improvement or maintenance purposes,
if the agency applying for the grant is in an air
quality control region where the following three
conditions apply: one or more federal primary stan-
dards have not been attained; transportation control
measures are necessary to achieve the standard being
violated; and an appropriate state implementation
plan has not been submitted (or reasonable efforts
toward developing such a plan are not being made).
This funding prohibition also applies if an approved
plan is not being implemented.
o After July 1, 1979 the U. S. Department of Trans-
portation is prohibited from awarding grants of
approving projects under Title 23, United States
Code, except for safety, mass transit, or trans-
portation projects which improve air quality, if
the agency applying for the grant funds or project
approval is in an air quality control region where
the three conditions cited above apply. This funding
prohibition also applies if an approved plan is not
being implemented.
o No federal agency can engage in, license, permit,
approve, or support in any way any activity which
does not conform to the approved or promulgated state
implementation plan for the relevant area.
o EPA is authorized to withhold, condition, or restrict
any grant for construction of sewage treatment faci-
lities if it is determined that: a) such sewage
treatment facilities will not comply with Clean Air
Act provisions relating to new source performance
standards or emission standards for hazardous air
pollutants; b) the state does not have, or is not
implementing, an approved state implementation plan
which expressly quantifies and provides necessary
management programs to deal with the air pollutant
emissions which may reasonably be anticipated to
result directly or indirectly from the new sewage
treatment capacity to be created by such construction;
c) the construction of such treatment works would
create new sewage treatment capacity which may
reasonably be anticipated to cause or contribute
to, directly or indirectly, a larger increase in
pollutant emissions than has been provided for
under the applicable state implementation plan; or
d) the construction of such treatment works would
create new sewage treatment capacity which would
cause or contribute to, directly or indirectly, an
increase in pollutant emissions which will interfere
with or be inconsistent with the applicable implemen-
tation plan of any other state.
105
-------
Emissions Inventories and Forecasts
CO emissions have been estimated for several groups
of emission sources in northern Ada County. The greatest
attention has been devoted to sources in the Boise metro-
politan area, since air quality monitoring data have docu-
mented serious CO problems throughout the Boise area.
Emission estimates have been structured to reflect historical
conditions for 1977 and 1980, and expected conditions for
1987 and 2000. Three broad categories of emission sources
have been evaluated: vehicle traffic on major roadways,
on- and off-street vehicle parking activity, and residen-
tial fuel combustion for space heating or appliance operation.
Commercial and industrial fuel combustion emissions have
not been estimated. Data for residential fuel combustion
suggest that commercial and industrial sources are probably
insignificant. Drive-up window facilities have not been
directly evaluated for the emission inventories and fore-
casts discussed here. Data for parking facilities suggest
that drive-up facilities may be significant localized emission
sources. Hourly emission inventory and forecast results
for the three major source categories are presented in
Appendix F.
Procedures used to produce the emission inventories
and forecasts are discussed in detail in Appendix A. All
forecasts were based primarily on the same population and
employment forecasts (APA 1978). Emissions from highway
traffic were based on traffic volumes projected by the
Boise area traffic model. Parking emissions were developed
using a variety of parking surveys from the Boise area.
Residential fuel combustion emissions were developed using
data from a recent survey of energy usage patterns (Elrick
and Lavidge 1980). All emission inventories and forecasts
were prepared in a manner allowing results to be summarized
by community planning area. The boundaries of community
planning areas as used for the Boise area traffic model and
the emission forecasting work are shown in Figures 7-9 and
7-10.
Results of the emission inventory and forecast work
are summarized in Table 7-1. As is apparent from this table,
use of wood stoves and fireplaces results in a significant
contribution to total CO emissions in the Boise area.
Because CO is a "primary" pollutant (i.e., emitted directly
rather than being formed through chemical reactions), the
total emissions burden in a regional area is not the best
indicator of contributions to ambient pollutant levels.
This point is illustrated by using a comparison which
accounts for both the quantity of emissions and the acreage
of the sources producing those emissions. Such a comparison
is shown in Table 7-2.
106
-------
A
N
A
.EGEIND-
^ BOISE METROPOLITAN AREA
^ EAGLE (70)
Q RURAL ADA COUNTY (90)
EH MERIDIAN (60)
HI KUNA (80)
|20I| TRAFFIC ZONE NUMBER
X
FIGURE 7-9. COMMUNITY PLANNING AREAS OUTSIDE
THE BOISE METROPOLITAN AREA
107
-------
FIGURE 7-10. COMMUNITY PLANNING
AREAS IN THE METROPOLITAN BOISE
AREA
NORTHWEST
(21)
-LEGEND-
(32) CPA NUMBER
BENCH (30)
WARM
SPRINGS
CENTRAL BENCH
SOUTHWEST (50
-------
Table 7-1. Summary of Carbon Monoxide Emission Forecasts for Northern Ada County
Planninq
Arrrt (CPM)
Sou
CBD
War
Sub
(10)
Subarea
(22)
m Springs
area
(23)
(24)
(25)
Emission
Source
Category
On- fc OFf-Strcet Parking
P'-Ti'lr-n* i-i 1 Parking
Wood Stoves
Fireplaces
Other Residential Fuels
Total
Wood Stoves
Fireplaces
Other Residential Fuels
Total
Highway Traffic
Wood Stoves
Fireplaces
Total
Wood Stoves
Fireplaces
Total
Residential Parking
Wood Stoves
Fireplaces
Total
Residential Parking
Wood Stoves
Fi replaces
Total
1977
10 am-6 pm
Period
20,926
1,802
1,434
313
1
11,912
591
619
1,494
135
606
132
51,843
4,988
157
421
1,017
92
4,061
232
736
161
6,968
247
2,147
5,194
469
32,254
1980
Total
35,375
3,495
2,859
1,355
19,674
941
1,233
5,500
584
1,207
572
1
89,720
8,391
270
398
1
13,642
6,821
474
1,468
696
16,007
646
4,279
19,088
2,028
l~S~, 8T3
Period
25,63
2,06
1,87
38
13,77
81
84
1,91
17
731
149
62,137
6,396
137
102
8,261
5,007
222
940
192
9,498
274
2,372
485
1
3s762o
Total
4 ,418
,072
,54'J
,660
3
2 ,977
,305
,598
,038
748
2
1,382
647
1
102,955
10,754
239
441
1
16,530
8,428
485
1,777
832
2
19,530
702
4,486
2,100
4
72,809
1987
23,900
1,422
1,872
678
2
35,381
11,881
742
889
3,564
322
1
511
185
1
45,155
4,817
220
118
6,785
5,807
117
758
275
9,999
173
1,372
497
I
2J.5BT
Daily
39,438
2,841
3,336
2,937
6
76,198
19,385
1,132
1,584
13,122
1,394
3
36,620
910
801
79,040
7,906
291
510
1
14,092
9,548
268
1,352
1,190
3
23,559
408
2,445
2,152
51,829
2000
10 ,im-fi pm
25,025
•H2
i ,r,ni
I3,0ft5
1,192
3
9,520
317
76S
6,272
566
17,44"5
362
2,961
267
1
5,075
77
205
1,675
151
7,18!
6,069
71
286
4,734
428
1
11,589
13,885
70
693
5,Gfi2
51 1
1
Daily
38,965
1 .73
2 ,80
48,17
5, 1)
96,81
14,97
48
1, 34
23,09
2,45
42,35
635
10,901
1,158
71,988
7,842
93
359
6,168
655
15,119
" 9,658
84
547
17,429
1,852
29,574
21,740
171
1,214
20,847
2,215
4
46,192
1977
10 am-6 pm Da t 1 y
74 . 9 63. 4
6.4 6.3
5.1 5.1
12.4 22.8
1.1 2.4
80.6 70.4
4.0 3.4
4.2 4.4
10.2 19.7
0.9 2.1
85.0 83.5
10.8 8.6
1.2 1.3
2.8 6.0
0.3 0.6
74.8 61.5
2.3 2.2
6.3 6.2
15.2 27.4
X.4 2.9
58.3 42.6
3.3 3.0
10.6 9.2
25.5 40.9
2.3 4.3
75.1 61.0
0.8 1.0
6.7 6.4
16.0 28.6
1.5 3.0
1980 1987
10 nn-fj pm Daily 10 ara-6 pa Daily
Ti.O 63.5 67.6 51.8
6.0 6.0 4.0 3.7
5.5 5.2 5.3 4.4
12.4 22.9 21.2 36.3
1. 1 2.4 1.9 3.9
78.6 68.2 68.3 52.9
4.7 3.9 4.3 3.1
4.8 4.7 5.1 4.3
10.9 20. 9 20.5 35.8
1.0 2.2 1.9 3.8
81.7 84.2 82.0 78.4
9.4 B.O 11.9 9.8
1.2 1.3 1.1 1.2
7.5 5.9 4.5 9.5
0.2 0.6 0.4 1.0
77.4 65.1 71.0 56.1
1.7 1.4 3.2 2.1
6.0 5.7 4.8 4.1
13.7 25.1 19.2 34.1
1.2 2.7 1.7 3.6
59.0 43.6 58.1 40.5
2.6 2.5 1.2 1.1
11.1 9.2 7.6 5.7
25.0 40. 4 30.4 47 .5
2.3 4.3 2.8 5.1
76.1 62.8 68.0 51.2
0.8 1.0 0.7 0.8
6.7 6.2 5.0 4.7
15. 1 27.1 23.3 39.1
1.4 2.9 2.1 4.2
2000
10 am-6 pm
59.9
2.2
3.8
31.3
2.8
54.6
l.B
4 . J
36.0
3,2
84.5
6.8
0.9
7.1
0.6
70.7
1.1
2.9
23.3
2.1
52.4
0.6
2.5
40.8
3.7
66.7
0.3
3.3
27.2
2.5
Daily
40.2
1.8
2.9
49.8
5.3
35.4
I.I
3.2
54.5
5.8
76.8
5.6
0.9
15.1
1.6
51.9
0.6
2.4
40.8
4.3
32.7
0.3
1.0
58.9
6.3
47.1
0.4
2.6
45.1
4.8
-------
Table 7-1 (cont'd.)
:-.!, rri0"
1 ) Cult- fir y
pr-,|.|r.ne 1 1 1 forking
Wr-o 1 StOVB
Total
On- t Off-Street Parking
rir-pUcnn
Tola I
Area Highway Tr.iffic
On- i orr-Str.^t Parking
Fi replaces
Total
otal On- t Off-Street Parking
Woo-1 Stoves
Oth«r Residential Fuels
Total
Area Highway Traffic
On- t Off-Streot Parking
Residential Parking
wood Stoves
Other Residential Fuels
Total
A Highway Traffic
On- i Off-Street Parking
Residential Parking
Hood Stoves
Fi replacoi
Other Residential Fuels
1977
10 am-fi pm
Period
5 , '< 4 '->
2, f,b
7, 1 37
2
87,658
65, 153
4, 397
3,859
9,3)6
842
6 3, 57l
38,691
1,797
921
2,223
201
43,B3"4
20, 366
13,698
33,077
2,968
8
355,375
17,156
NC
633
1,734
157
19,680
5,623
NC
273
790
71
Doily
Total
8, 226
5 , Fn 0
26.27S
2,792
G
112, 101
6,871
7 , 691
34, 3)0
3,645
164,626
66, 143
2,843
1,835
6,187
870
79,879
31,441
27,299
121,789
12,940
26
678,402
28,667
1,457
6, 386
679
37,190
9,387
NC
628
2,908
309
1980
10 am- 6 pra
Period
5,643
3,458
7,823
707
2
71.4)9
1, 140
4,303
9,735
879
91,466
44,348
1,814
1,182
2,673
241
50,259
22,163
16,204
36,660
3,311
407,160
19,306
794
161
22,288
6,391
NC
366
951
86
Daily
Total
8,743
6,542
28, 605
3,061
6
122,987
8,008
8.141
35,846
3 , 809
178,798
75,707
2,937
1 ,046
91,769
34 ,677
30,655
14,342
29
774,000
32,296
1,693
785
42,163
10,677
NC
785
3,503
372
0
10 ™-r, pm
Period
3 , 757
2
54, 115
3
70,660
35,530
1,507
1
41,655
247,332
15,963
11,458
4,150
324,882
10,276
672
272
14,229
6,OB5
NC
320
1 ,427
129
D.a 1 1 y
Total
5,5)2
4 .OHO
7
90,442
4 .600
4 , 049
8
141 , 340
56 , 848
2,377
3
76,799
410,271
24 ,738
20,419
17,975
642,619
16,830
1,334
1,177
30,419
9,941
NC
633
5,254
558
1
10 ,1F
Per
2
1
1 1
'
67
37
1,
1,
11
1
53
36
5,
477
7 ,
63,
5,
305,
10,
5,
2000
-6 pm
246
409
•j 1 7
3
428
243
455
886
074
"OT9
1 38
171
661
566
503
"oTo
945
460
358
723
16
138
516
626
606
506
1
17,255
5,
2,
293
293
591
234
1
TT2
1 1 n 1 1110 1 IMI
Total Porioil T.JL.I! Period Total P..] i<>'1
. . _
2 , -1 £ 9 j . 4 J . b 1.4 3.4 3.1
42,407 8.1 16.0 7.7 1 ri . 2 1J4
4,S06 0.7 1.7 0.7 1.6 1.1
9 -
134,526
60,702 78.0 6P.1 7B.1 6B.8 706
1,814 5.3 4.2 1.6 4.5 J. 8
2,548 4.6 4.7 4.7 4.6 3.7
43, 7fi5 11.1 20.8 10.6 20.0 1 4 . f,
4,650 1.0 2.2 1.0 2.1 1.3
11 3,569
56,346 88. 3 82. 8 88. 2 82.5 85. 3
1 ,823 4.1 3.6 3.6 3.2 36
1 ,193 2.1 2.3 2.4 2.4 2.1
20,495 5. 1 10. 2 5.3 10.7 8. 3
2, 178 0.5 1.1 0.5 1.1 0.7
82,039
3,515 5.7 4.6 5.4 4.5 49
3,H5 3.9 4.0 4.0 4.0 35
2 3,285 9. 3 18.0 9.0 17.4 141
1.787 0.8 1.9 0.8 1.9 13
50 - _ _
632,175
16,440 87. i 77.X 86.6 76.6 72.2
»C NC NC HC NC NC
1.204 3.2 3.9 3.6 4.0 4.7
20.643 8.8 17.2 9.0 17.5 21.1
2,193 0.8 1.8 0.8 1.9 19
40,484
6. 278 83. i 70.9 82.0 69.6 76 <•
NC NC NC NC NC NC
562 4.0 4.7 4.7 5.1 40
9.540 11.7 22.0 12.2 22.8 17.9
1.014 l.i 2.3 1.1 2.4 1.6
I "MB
2.5 l.'j
2.9 2.0
76.fi 82.0
1.6 1.1
38 2.9
26.3 20.6
NC NC
36.4 32.5
60.7 62.9
NC NC
3.9 3.5
32.) 30.8
3.4 2.8
— _ __
4 . 1
68.7
2 . 7
2, )
36. 9
-
NC
51.0
42.7
NC
2.9
49.2
5.2
-------
Table 7-1 (cont'd.)
Communi ty
Plnnnintj
Area (CFA<)
(801
Area
(901
A'la County
Notes and Sources:
Residential parking
Emission
Source
Category
Ui-jliw.iy Traffic:
On- & Off-Street Parking
Hood Stoves
Firrplaces
Other Residential Fuela
Total
On- <. Ot£-Sircct Parking
Residential Parking
Wood Stoves
Fireplaces
Other Residential Fuela
Total
Highway Traffic
On- t. Orr-streit Parking
Fireplaces
Other Residential Fuels
Total
1977 I960
10 flin-6 pm Dally 10 am-6 pm Daily
Period Total Period Tobal
MC NC NC NC
117 262 154 328
366 1,348 4SO 1,659
33 143 41 176
1,376 3,184 1,681 3,894
NC NC NC NC
657 1,519 805 1,731
1,977 7,278 2,214 8,151
179 773 200 866
2 12
59,238 103,588 66,859 116,878
365 304 618,405 419 180 710,142
20 368 31,441 22 163 34,677
9 30 10 33
component separated from total parking emissions by applying a programmable
are due primarily to procedures used to estimate home-based vehicle trips for each CPA.
1987
10 am- 6 pm D.ii ly
Period Total
8G4 1,409
NC NC
159 309
759 2,796
69 297
- _ 1
NC NC
60 1,186
2,82 10,418
25 1,107
2
48,09 85,177
30-8 96 510,915
15 98 24,738
1 42
calculator version of the
r.ing. Inconsistencies
2000
10
-------
Table 7-2. Carbon Monoxide Emission Densities in Northern Ada County
t 1977 19BO _ 19H7 2000 1977 1980 ma-, ,„„„
r'u^n?!1! V r,~-,T->* " 10 fim-G pm D.iily 1" nm-6 pm D.iil
»__,,(.. 1 1 C )* '"lorv pfjr 1 nd To La I Period Tota
_r_t* _lk_ •! ' ' i-J'-I- JHii — !_J-
8outn?.i t Area Highway Traffic 12
Residential Packing
Residential Fuel Uen
ESDI* 15
(21) On- I Off-Str^nt Parking 3
P»Rldontinl Parking
Residential ruol Use
ESDI^ i*
CBD Subaraa Highway Traffic 23
(22) On- t Off-Street Parking 4
Rcn.id"ntinl Parkinq
Ro«l •,
.99 32.03 8.87 13.62 21 3 200 "' ,l°, ',]'l ?°'S 88'2 84.7
.76 1.35 0.37 0.65 0.8 09 07 as 'J'f 13lG '•< '••
.31 12.38 3.31 12 37 20 44 ? . °'5 °'6 °.3 0.4
775 2367T5 lot .-61 mtTt '•' 3'9 2'3 5-2 3.1 7.1
•'» 304.48 172.14 271.34 83.7 84 9 85 4 86 3
•},' 'I'll I'M '^t? "•' U'° "il lo!9 l,\l 91 ; ; 'I''
•" ll35 0'37 O-65 0.4 0.5 0.4 05 04 n'i „', 4'6
7^7 350^: niHi iHtS '•' 2-6 '•« -3 ?•'! 5:1 !:! j:j
:» "»:J5 '}?:» 2?i:!5 I!:! ;;•; ;M »•; ».j «.. 5o.s „.,
.76 1.J5 0.37 0.65 0.7 oi 8 06 o'? n'l U'5 6'9 S'J
tU TTirM T>jHj liltll '•• 3-' ':» 3^ 5:J 5:3 5:^ !:J
.65 86.56 55.02 87.56 56 1 50 7 fil o cc i
.98 32.03 11.51 13.62 422 463 \l'l JI'J "'! 7l'» »•' 84.0
.18 0.33 0.04 0.09 0.5 05 ol Is ^'l "'J "-1 '1.1
ii T217H TfrH ToitH !-J 2-5 ^ °" "2 !:J I:! 5:J
:5J 25S:K "1:5! l;;:!5 K:J !J-,e •;•« JJ-S ".-I
•76 1.35 0.37 0.65 0 6 06 OS n'< 1KJ <•' «•'
-^ jBtH i357fi iMrfj '-' 3:z i:< °» °'*° !:! 5:J SJ
.46 185.75 99.39 158.32 77 a 78 3 70 . ,„ ,
•ll ">'°l I'M ",X *°0-l J: •: »: !i:J ?!:! 1:S •?:!
H* tiHI nliS lifrS '•' °- - S:5 5:? U ;:j j:j
-------
Table 7-2 (cont'd.)
Arii-lUEk1.1 Siisasrjf
Central Bench Highway Traffic
hro-i On- d off-Str""t Parking
(4n) Residential Parking
Residential Fuel Use
ESDI'
Southwest Arr-a Iliohway Traffic
(50) On- f. Off-Street Parking
Residential Parking
Residential Fuel Use
ESDI*
ivvcriq*-. Boise Highway Traffic
Metropolitan On- t Off-Street Parking
Area Residential Parking
Residential Fuel Use
ESDI J
Meridian Area Ilighw-iy Traffic
(60) On- b Off-Strect Parking
Pesidential Parking
Residential Fuel Use
ESDI'
Eaql- Area Highway Traffic
,70) On- 6 Off-Street Parking
Residential Parking
Residential Fuel Use
ESDI'
Kuna Area Highway Traffic
,ao) On- fi Off-Street Parking
Residential Parking
Residential Fuel Use
ESDI7
j Rural Ada County Highway Traffic
,..„- On- 6 Off-Street Parking
J " ,-,„, Pesidential Parking
Residential Fuel Use
ESDI1
Averaae, Northern Highway Traffic
Ada County On- 6 Off-Street Parking
Residential Parking
Residential Fuel Use
ESDI*
WliES AMD SOURCES:
MC = Not calculated due to lack of parking su
ITTL^.,.
10 ntn-6 pm Dally
Pe r i ocl Tqt.il
170.64 293. GO
3fi, 19 56.56
0.18 1.96
2.59 1-66
210.40 361 .78
66.09 112.98
35.75 S6.56
0.40 0.80
1.05 3.93
103.29 174.27
131.31 223.24
36,64 56.56
0.88 1.75
2.32 8.65
136. OR 290.20
72.21 120.66
NC NC
0.81 1.87
2.42 9.06
75.44 131.59
73.63 122.93
NC NC
0.77 1.77
2.43 9-06
76.83 133.76
11.26 18.74
NC NC
0.71 1-59
2.42 9.04
~~T4 — 39" 29. 37
28.42 47.35
NC NC
0.25 0.57
0.81 3.02
~29.«"7~ 50.94
80.32 134.72
36.64 56.56
0.79 1.59
2.12 7.91
119/87 200.78
rvcy data.
'Relative Emission Density = Source category emissions from Table 7-1
II iqhwoy acrca'jf? basnd on roadway miles (Table1 7-3) and assume'l avoi
parking acrp.Tj" estimated for Boise Metropolitan Area as a whole 1131
assumnd average of 420 square feet per parking space. Average sourc
for all component CPAs. 10 a.m. -6 p.m. values for each CPA calculat
Residential acreages from Table 7-3 used for
residential parking and
10 am-C pm Daily
Period Toj.nl,
187.05 322.11
37.6-1 58.53
1.05 1.98
2.5'J 9.66
228.33 392.30
75.75 129.31
36.16 58.55
0.43 0,81
1.05 3.92
lU. 39 192.59
148.48 253.55
37.42 58.55
0.93 1.75
2,28 8.53
189.11 321.38
81.26 135,94
NC NC
0.88 1-87
2.42 9.05
"84.56 146.86
83.69 139.82
NC NC
0.86 1.83
2.42 9.06
86.97 150.71
13.57 22.67
NC NC
0.76 1-62
2.42 9.04
16.75 33.33
32.05 53.45
NC NC
0.27 0.5B
O.HI 3.02
33.13 57.05
91,32 154.70
37.42 58.55
0.83 1.60
2.09 7.82
F59.29 222.67
divided by estimated fie
age roadway width of 70
R density for metropolit
cd from ratio of 8-hour
residential fuel use ca
i 'in r
10 am- 6 |im
Period
. 130,65
20.70
0.59
2.59
T62759
60.69
20. 31
0.24
TH?
106.00
20.70
0.52
2.26
129.46
4B.44
NC
0.50
2.42
51.36
59.76
NC
0.50
2.42
62.68
11.31
NC
0.46
2.42
23.36
NC
0.16
o.ai
24. 33
66.81
20.70
0.47
2.07
90.05
eage of cmlss
ec-t. On- and
Otii ly
Sfttai
231.72
32.03
1.05
_i*6
274. 4C
100.52
32.03
0.43
3.92
136 ","90
175.83
32.03
0.92
8.43
217.21
79.34
NC
0.99
9.06
B9.39
97.63
NC
0.99
9.05
107.67
18.45
NC
0.90
9.05
2B.40
38.13
NC
0.31
3.02
41.46
110.49
32.03
0.84
7.75
107.43
of f-stree
king facility data Hie
n area used as daily to
o daily emissions in Ta
egories.
2000.
H) nm-C pm
Porlotl
95. B9
0.94
0.29
2.59
157771
61 .73
8.75
0. 12
1.05
94.13
9.02
0.24
2.19
105.58
49. 58
NC
0.25
2.42
52.25
51.98
NC
0.25
2.42
54765
10.40
NC
0.22
2.43
13.05
18.67
NC
0.08
0.81
58.76
9.02
0.22
2.04
70.04
category.
I
tal value
ble 7-1.
itn 1 1 y
To£ol_
155.53
13. G2
0.51
9.66
179.32
96. 24
13.62
0.21
3.92
113.99
140.90
13.62
0.42
B.20
171.14
77.50
NC
0.48
9.06
87.04
81. 30
NC
0.48
9.05
"90.83
16.46
NC
0.43
9.06
25.95
29.51
NC
0.15
3.02
32.63
92. 88
13.62
0.39
7.62
114.51
1977
10 iim-0 pm
Peri oil
81. 1
17,2
0.5
1.2
64.0
34.6
0.4
1.0
70.7
26.9
0.6
1.7
95.7
NC
1.1
3.2
95.8
NC
1.0
3.2
78. 2
NC
4.9
16.8
96.4
NC
O.B
2.7
67.0
30.6
0.7
1.8
D/illy
Total
BL.2
15.6
0.5
2.7
64.8
32.5
0.5
2.3
76.9
19.5
0.6
3,0
91.7
NC
1.4
6.9
9L.9
NC
1.3
6.8
63.8
NC
5.4
30. B
93.0
NC
1.1
5.9
67.1
28. 2
0.8
3.9
Pa tec
1900
10 nm-6 pm
Bl. 9
16, r.
0.5
1.1
66.0
31.9
0.4
0.9
78.5
19.9
0.5
1.2
96.1
NC
1.0
2.9
96 . 2
NC
1.0
2.8
Bl . 0
NC
4.5
14.4
96.7
NC
0.8
2.4
57. 3
36. B
1.0
4.9
nt Contrib
Dully
Total
14.9
0.5
2.5
67. 1
SO. 4
0.4
2.0
7B.6
18.2
0.5
2.7
92.6
NC
1.3
6.2
NC
1.2
6.0
NC
4.9
27.1
93.7
NC
1.0
5.3
69. 5
26.3
0.7
3.5
ution 10 ESDI'
10 nm-6 pm
85 , 3
12.8
0.4
1.6
24.7
0.3
1.3
16.0
0.4
1.7
94 . 3
HC
1.0
4.7
95. 3
HC
O.B
3.9
79. 7
NC
3.2
17.1
96.0
NC
0.7
3.3
23.0
0.5
2.3
D.i i ly
Total
84.4
11,7
0.4
3.5
73 . 4
23,4
0.3
2.9
80. 9
14.7
0.4
3.9
NC
1.1
10.1
90.7
HC
0.9
B.4
65.0
HC
3.2
31.9
92.0
HC
0.7
7.3
62. 2
29. B
0.8
7.2
2000
10 am- 6 pm
B9.0
8.3
0.3
2.4
86. 2
12,2
0.2
1.5
89. 2
8.5
0.2
2.1
94.9
HC
0.5
4.6
95.1
HC
0.5
4.4
79.7
HC
1.7
18.6
95.4
NC
0.4
4.1
83.9
12.9
0.3
2.9
U.ii ly
Total
86,7
7.6
0.3
5.4
84.4
11.9
0.2
3.4
87.0
8.0
0.2
4.8
89.0
HC
0.6
10.4
89.5
NC
0.5
10.0
63.4
NC
1.7
34.9
90. i
NC
0.5
9.2
81. 1
11.9
0.3
6.7
-------
The emission source density values in Table 7-2 indicate
that vehicle activity (highway traffic and parking activities)
is clearly the dominant factor in existing CO problems.
Current and projected composite emission source density
index (ESDI) values for the various community planning
areas in the Boise area are shown in Figures 7-11, 7-12, and 7-13
The dominant influence of vehicle emissions is also apparent
from the ambient air quality monitoring data discussed pre-
viously. Data used to develop the ESDI values, as well as
other pertinent characteristics of each community planning
area, are summarized in Table 7-3.
The significance of different emission source categories
cannot be fully evaluated solely from the percent contribution
columns of Table 7-1 or 7-2. The percent contribution of
any source category is, to a major extent, a reflection of
the significance of other sources in a particular community
planning area. For example, 1980 on- and off-street parking
emissions in the Foothills subarea contribute substantially
to the ESDI value (Table 7-2). This is largely a reflection
of the minimal amount of vehicle traffic in that area, rather
than an indication of massive amounts of parking-related
emissions (compare Tables 7-1 and 7-2).
Future Air Pollution Potential
in Ada County
The implications of projected emission levels have been
evaluated using simple proportionality ("rollback") techni-
ques (see Appendix H). Each community planning area has
_been analyzed as a discrete subarea, without considering
the possibility of pollutant transport between areas. The
use of such procedures requires selection of a base year
from which to extrapolate potential pollution levels. The
ambient monitoring data summarized previously show that the
1976-1977 period experienced the most frequent and severe
CO episodes yet reported. The emission inventories presented
in Table 7-1 indicate that recent reductions in the frequency
and magnitude of pollution episodes do not result from reduc-
tions in pollutant emissions. Meteorological conditions
(inversion frequency and intensity, wind conditions, etc.),
appear to be the controlling factors. Thus, 1977 represents
an indicator of potential CO levels under unfavorable weather
conditions.
The procedures used for this analysis have not dealt
with the possibility of significant pollutant transport
between community planning areas. As discussed in Appendix G,
available monitoring data demonstrate only neighborhood scale
transport events.
114
-------
FIGURE 7-11. I960 EMISSION SOURCE
DENSITY INDEX VALUES (DAILY BASIS)
FOR THE BOISE METROPOLITAN AREA
-LEGEND-
100-150
150-ZOO
300-350
350-400
400-450
500 +
WARM
SPRINGS
(23)
-------
FIGURE 7-12. 1987 EMISSION SOURCE
DENSITY INDEX VALUES (DAILY BASIS)
FOR THE BOISE METROPOLITAN AREA
FOOTHILLS
-124)
SOUTHWEST
-------
FIGURE 7-13. 2000 EMISSION SOURCE
DENSITY INDEX VALUES (DAILY
BASIS) FOR THE BOISE METROPOLITAN
AREA
-LEGEND-
CD 100-150
150-200
200-250
250-300
SOUTHWEST (50
-------
Table 7-3. Community Planning Area Characteristics Reflected in the Emission Inventories and Forecasts
Community Planning Area (CPA f)
Southeast Area (10)
Northwest Subarea (21)
CBD Subaroa (22)
Warm Springs Subarea (23)
Foothills Subarea (24)
Northend Subarea (25)
West Bench Area (30)
Central Bench Area (40)
Southwest Area (50)
Subtotal, Boise
Metropolitan Area
Year
1977
1980
1987
2000
1977
1980
1987
2000
1977
1980
1987
2000
1977
1980
1987
2000
1977
1980
1987
2000
1977
1980
1987
2000
1977
1980
1987
2000
1977
1980
1987
2000
1977
1980
1987
2000
1977
1980
1987
2000
Population '
13,578
16,808
29,702
49,831
6, 327
7,853
14,411
24,455
3,178
3,534
4,366
6,655
3,698
4,003
4,553
5,574
7,603
8,921
12,529
18,850
17,458
17,874
17,957
18,110
30,276
32,640
37,565
45,115
36,749
37,716
39,248
43,355
10,277
12,072
14,914
22,380
129,144
141,427
175,244
234,050
Dwelling
Units 1
4,675
5,728
10,132
17,661
2,016
2,580
4,810
8,465
1,974
2,231
2,765
3,996
1,372
1,522
1,761
2,261
2,400
2,869
4,105
6,389
6,997
7,244
7,426
7,642
9,633
10,559
12,393
15,545
12,577
13,140
13,971
16,043
3,001
3,608
4,652
7,513
44,644
49,481
62,016
85,516
Total
Acreage 1
8,503
8,503
8,503
8,503
3,880
3,880
3,880
3,880
1,084
1,084
1,084
1,084
1,090
1,090
1,090
1,090
14,021
14,021
14,021
14,021
2,141
2.. 141
2,141
2,141
11,182
11,182
11,182
11,182
6,198
6,198
6,198
6,198
18,383
18,383
18,383
18,383
66,482
66,482
66,482
66,482
Residential
Acreage 2
1, 169
1,432
2,533
4,415
492
629
1,173
2,065
481
544
674
975
335
371
430
551
2,400
2,869
4,105
6,389
1,707
1,767
1,811
1,864
2,752
3,017
3,541
4,441
3,930
4,106
4,366
5,013
2,308
2,775
3,578
5,779
15,574
17,510
22,211
31,492
Roadway
Miles 3
20
22
33
33
11
11
12
12
22
22
24
24
4
4
4
4
13
13
13
13
15
15
13
13
57
60
61
61
45
45
46
46
69
69
69
69
256
261
275
275
Daily Vehicle
Mi j es
Traveled 3
1] 8, 241
147,878
270,901
495,573
78,560
92,402
153,431
229,285
221,750
257,537
360,418
596,172
30,569
40,043
57,951
100,696
24,645
31,026
71,089
143,629
142,791
161,512
178,029
260,063
462,544
538,089
699,132
1,102,625
411,511
456,623
637,459
843,049
271,411
313,706
472,042
800,122
1,762,022
2,038,816
2,900,452
4,571,214
Daily Home-
Based Vehicle
Trips ''
34 ,556
43,266
80,827
148, 887
14,902
19,488
38,371
71, 362
14,591
16,852
22,058
33,687
10,141
11,496
14,048
19,061
17,740
21,671
32,747
53,861
51,720
54,717
59,240
64,424
71,204
79,757
98,864
131,049
92,965
99,253
111,453
135,247
22,182
27,253
37,111
63,337
329 , 995
373,753
494 ,728
720,925
-------
Community Planning Area (CPA #)
Meridian Area (60)
Eagle Area (70)
Kuna Area (80)
Rural Ada County Area (90)
Total, Northern Ada County
Year
1977
1980
1987
2000
1977
1980
1987
2000
1977
1980
1987
2000
1977
1980
1987
2000
1977
1980
1987
2000
Dwelling
Population1 Units1
7,295
8,593
12,639
22,122
3,152
3,800
5,696
10,225
1,626
2,004
3,301
6,415
8,507
9,393
11,794
15,913
149,724
165,211
208,674
289,000
2,341
2,708
4,060
7,567
1,066
1,284
1,926
3,497
494
608
1,025
2,101
2,668
2,988
3,819
5,278
51,213
57,069
72,847
103,958
Total
Acreage 1
10,560
10,560
10,560
10,560
9,728
9,728
9,728
9,728
3,520
3,520
3,520
3,520
335,598
335,598
335,598
335,598
425,888
425,888
425,888
425,888
Residential
Acreage 2
1
2
1
2
2
3
5
19
22
28
41
780
903
,353
,522
355
428
642
,166
165
203
342
700
,668
,988
,819
,278
,542
,032
,367
,158
Roadway
Miles 3
28
28
25
25
9
9
12
12
9
9
9
9
234
234
224
224
536
541
545
545
Daily Vehicle
Miles
Traveled 3
111,
127,
129,
235,
36,
42,
77,
122,
5,
7,
11,
20,
379,
433,
533,
837,
2,295,
2,648,
3,652,
5,787,
456
620
427
621
810
199
992
956
791
082
296
265
333
013
280
644
412
730
447
700
Daily Home-
Based Vehicle-
Trips ••
17
20
32
63
7
9
15
29
3
4
8
29
19
22
30
44
378
431
581
876
,304
,394
,388
,792
,880
,699
,365
,481
,651
,593
,177
,675
,721
,570
,466
,495
,551
,069
,132
,396
Notes and Sources:
tabulated from data in APA 1978, reflecting traffic zone aggregations as used in the Boise traffic model.
2Calculated from dwelling unit values assuming 4.0 units per acre in CPA 10; 4.1 units per acre in CPAs 21, 22, 23, and 25;
1.0 unit per acre in CPAs 24 and 90; 3.5 units per acre in CPA 30; 3.2 units per acre in CPA 40; 1.3 units per acre in CPA 50;
and 3.0 units per acre in CPAs 60, 70, and 80. Dwelling unit per acre values selected by Jones & Stokes Associates staff
based on data in APA 1978.
3From Boise traffic model output; computer runs made in November 1980.
"•Calculated for each CPA using areawide average trip generation rates; areawide trip generation rates calculated separately for
each forecast year from traffic model output of total home-based vehicle trips and total dwelling units listed above. All vehicle
trip numbers represent sum of trips in both directions. Values are preliminary estimates, subject to revision when specific
CPA summaries become available directly from the traffic model.
-------
Estimates of future air pollution potential are pre-
sented in Table 7-4. Potential CO levels were analyzed as
two components: a "background" increment related to total
emissions in each planning area, and a roadway corridor
increment related to highway traffic and nonresidential
parking emissions. Table 7-4 makes it clear that CO prob-
lems can be expected to persist at least to the year 2000
in several portions of the Boise metropolitan area. The
effects of existing vehicle emission control requirements
are accounted for in the emission forecasts used for this
analysis.
The procedures used to develop Table 7-4 have also been
used to estimate the extent of emission reduction which
would be necessary to predict attainment of the federal
8-hour CO standard in each of the four analysis years
(Table 7-5). To meet the 1987 deadline established by
the Clean Air Act, projected 1987 emissions must be reduced
by as much as 53 percent in some community planning areas.
The greatest emission reduction requirements for the 1987
period apply to the Central Bench, CBD, and West Bench
community planning areas. The extent of emission reduction
requirements for 1987 and 2000 are shown in Figures 7-14
and 7-15.
Table 7-6 summarizes the assumptions used in this
analysis regarding 1977 background CO increments and overall
8-hour CO levels. Background CO values for the CBD area
were selected after reviewing the hourly CO data for the
downtown monitoring station. Background CO values for other
planning areas were selected on the basis of other monitoring
data and the emission source density index values for 1977.
Base year ambient CO values for each planning area were developed
separately for valley and bench areas. Data from the downtown
monitoring station were used for valley areas. The second-
highest 8-hour CO episode for 1977 (18.3 ppm) was assigned
to the CBD area. Base year CO values for other planning
areas were extrapolated from this on the basis of emission
source density index values. A similar procedure was used
for the bench areas. The second highest 8-hour CO event
reported from the Idaho Air Quality Bureau special CO study
(21.0 ppm) was assigned to the central bench planning area.
Emission source density index values were used to extrapolate
base year CO values for other planning areas.
The Southeast area (CPA 10) deserves some special dis-
cussion. This planning area was treated as a valley location.
The western end of the area, however, is on the bench. The
Idaho Air Quality Bureau special study reported an 8-hour
CO value of 17.7 ppm from a site along Broadway Avenue. This
is substantially higher than the 10.2 ppm CO value assigned
to this planning area in Table 7-6. The 10.2 ppm value seems
quite reasonable for most of the Southeast area. Interpretation
of Tables 7-4 and 7-5 (as well as Figures 7--14 and 7-15)
120
-------
Table 7-4. Forecasts of Air Pollution Potential
Community Planning
Area (CPA # )
Southeast Area (10)
Northwest Subarea (21)
CBD Subarea (22)
Warm Springs Subarea (23)
Foothills Subarea (24)
Northend Subarea (25)
West Bench Area (30)
Central Bench Area (40)
Southwest Area (50)
Meridian Area (60)
Eagle. Area (70)
Kuna Area (80)
Rural Ada County Area (90)
Emission
Forecast
Basis
10 am-
Daily
10 am-
Daily
6 pm
Total
6 pm
Total
10 am- 6 pm
Daily
10 am-
Daily
10 am-
Daily
10 am-
Daily
10 am-
Daily
10 am-
Daily
10 am-
Daily
10 am-
Daily
10 am-
Daily
10 am-
Daily
10 am-
Daily
Total
6 pm
Total
6 pm
Total
6 pm
Total
6 pm
Total
6 pm
Total
6 pm
Total
6 pm
Total
6 pm
Total
6 pm
Total
6 pm
Total
Potential 8-Hour Carbon
Monoxide Levels (ppm)
197
10.
10.
10.
10.
18.
18.
12.
12.
4.
4.
14.
14.
18.
18.
21.
21.
10.
10.
7.
7.
5.
5.
1.
1.
2.
2.
7
2
2
8
8
3
3
0
0
3
3
1
1
9
9
0
0
3
3
5
5
0
0
4
4
9
9
1980
12.
12.
12.
12.
21.
21.
15.
15.
5.
5.
15.
15.
22.
22.
23.
23.
11.
11.
8.
8.
5.
5.
1.
1.
3.
3.
4
5
7
7
0
0
2
1
2
3
8
8
1
2
1
1
7
8
4
5
7
7
7
7
3
3
1
1
987
1.
11.
1
1
1
1
1
1
1
1
1
1
1.
1.
5.
5.
1.
1.
6.
5.
9.
9.
5.
5.
7.
6.
9.
9.
4.
4.
5.
5.
1.
1.
2.
2.
5
4
2
1
7
5
8
5
0
8
5
4
3
0
2
8
5
2
6
5
5
4
4
4
3
2
2000
12.
11.
8.
8.
14.
13.
12.
11.
6.
6.
8.
7.
13.
12.
11.
11.
9.
8.
4.
4.
4.
4.
1.
1.
1.
1.
0
4
2
9
1
3
1
3
3
0
2
8
3
7
8
4
6
9
7
6
9
7
4
4
8
7
NOTES AND SOURCES:
Forecasts prepared using simple proportionality ("rollback") proce-
dures, with "background" CO increment proportional to change in total
CPA emissions and "corridor" CO increment proportional to change in
highway plus nonresidential parking emissions for CPA. Each CPA
treated separately (no pollutant transport between CPAs).
1977 used as a uniform base year, since that year showed the highest
ratios of observed CO levels to estimated emissions.
"Background" and base year ambient CO values for each CPA shown in
Table 7-6. Emission estimates and forecasts shown in Table 7-1.
ppm = parts per million, by volume.
121
-------
Table 7-5. Reductions From Projected CPA Emissions Required
To Indicate Attainment of 8-Hour CO Standard
ro
NJ
Community
Planning
Area (CPA#)
Southeast Area (10)
Northwest Subarea (21)
CBD Subarea (22)
Warm Springs Subarea (23)
Foothills Subarea (24)
Northend Subarea (25)
West Bench Area (30)
Central Bench Area (40)
Southwest Area (50)
Meridian Area (60)
Eagle Area (70)
Emission
Forecast
Basis
10 am- 6 pm
Daily Total
10 am- 6 pm
Daily Total
10 am- 6 pm
Daily Total
10 am- 6 pm
Daily Total
10 am- 6 pm
Daily Total
10 am- 6 pm
Daily Total
10 am- 6 pm
Daily Total
10 am-6 pm
Daily Total
10 am-6 pm
Daily Total
10 am-6 pm
Daily Total
1 0 am- 6 pm
Daily Total
Required Percent Reduction
From Projected Emissions
1977
13.04
13.04
18.37
18. 37
57.06
57.06
28.57
28.57
0.0
0.0
42.15
42.15
56.90
56.90
63.16
63.16
13.98
13.98
0.0
0.0
0.0
0.0
1980
30.64
30.82
32.33
32.47
64.50
64.19
46.30
46.11
0.0
0.0
49.90
49.75
64.45
64.43
67.44
67.36
25.93
25.95
0.0
0.0
0.0
0.0
1987
24.55
23.70
21.67
21. 17
47.92
47.47
27.12
25.03
0.0
0.0
6.04
5.47
44.85
43. 92
52.89
51.78
5.38
2.61
0.0
0.0
0.0
0.0
2000
28.53
24.57
0.0
0.0
40.57
36. 83
29.59
23.74
0.0
0.0
0.0
0.0
35.42
32.36
26.83
23.77
6.71
0.0
0.0
0.0
0.0
0.0
-------
Table 7-5 (cont'd.)
Community
Planning
Area (CPA#)
Kuna Area (80)
Rural Ada County (90)
Emission
Forecast
Basis
10 am- 6 pm
Daily Total
10 am- 6 pm
Daily Total
Required Percent Reduction
From Projected Emissions
1977
0.0
0.0
0.0
0.0
1980
0.0
0.0
0.0
0.0
1987
0.0
0.0
0.0
0.0
2000
0.0
0.0
0.0
0.0
Notes and Sources:
Based on proportionality (rollback) procedures discussed in text.
Supporting emission forecasts presented in Table 7-1.
NJ
U)
-------
FIGURE 7-14. EMISSION REDUCTIONS
NEEDED TO ACHIEVE THE 8-HOUR
CO STANDARD IN 1987
NORTHWEST
WEST BENCH
WARM
SPRINGS
J23)
SOUTHWEST
-------
FIGURE 7-15. EMISSION REDUCTIONS
NEEDED TO ACHIEVE THE 8-HOUR
CO STANDARD IN 2000
-------
Table 7-6. Base Year (1977) Air Qualit^
Used for Rollback Analyses
Community Planning
Area (CPA #)
Background Total Ambient Emission Source
CO (ppm) CO (ppm) Density Index
Southeast Area (10)
Northwest Subarea (21)
CBD Subarea (22)
Warms Springs Subarea (23)
Foothills Subarea (24)
Northend Subarea (25)
West Bench Area (30)
Central Bench Area (40)
Southwest Area (50)
Meridian Area (60)
Eagle Area (70)
Kuna Area (80)
Rural Ada County Area (90)
1.
1.
2.
1.
0.
2.
1.
2.
1.
0.
0.
0.
0.
0
0
0
5
5
0
5
0
0
5
5
1
1
10
10
18
12
4
14
18
21
10
7
5
1
2
.2
. 8
.3
.0
. 3
.1
. 9
.0
. 3
- 5
.0
.4
. 9
156.
166.
281.
184.
65.
216.
189.
210.
103.
75.
76.
14.
29-
93
65
58
72
62
40
63
40
29
44
83
39
47
NOTES AND SOURCES:
10 am-6 pm Emission Source Density Index (ESDI) values from Table 7-2.
Total ambient CO value for CPA 22 is second high 8-hour average for
1977 as reported by the Ninth Street monitoring station.
Total ambient CO value for CPA 40 is the second high 8-hour average
reported by the Idaho Air Quality Bureau special study in 1977-1978
(Idaho Air Quality Bureau 1978).
Ambient CO values for CPAs 10, 21, 23, 24, 25 and 70 calculated from
value for CPA 22, based on relative ESDI values.
Ambient CO values for CPAs 30, 50, 60, 80, and 90 calculated from
value for CPA 40, based on relative ESDI values.
Background CO values assigned on a judgmental basis following inspec-
tion of hourly CO values at the Ninth Street monitoring station and
comparison of ESDI values by CPA.
126
-------
should recognize that the portion of the Southwest area near
Broadway Avenue is effectively an extension of the central
bench area.
Except for this one situation, the base year CO values
assigned in Table 7-6 are in agreement with all available
ambient monitoring data.
The analyses presented above have not included the
effects of any vehicle inspection and maintenance program
for Ada County. If such a program were implemented, pro-
jected vehicle emissions would be reduced by about 20-25
percent. This level of emission reduction would still be
insufficient to provide for attainment of the 8-hour CO
standard in the Central Bench, CBD, West Bench, and Warm
Springs areas.
The APA is currently reviewing a number of additional
measures which could be implemented to help achieve air
quality standards throughout Ada County- Measures currently
under consideration include:
o Improved public transit (short-term and long-term
programs).
o Carpool/vanpool programs.
o Park and ride facilities.
o Traffic flow improvements through signalization
programs, intersection design changes, added road
lanes; many specific roadway and intersection
improvements are already accounted for in the
emission forecasts (see Appendix A).
o Exclusive bus and carpool lanes.
o Parking management programs (controls on the loca-
tion and duration of on- and off-street parking;
parking costs; supporting park and ride programs;
facility design and operation; etc.).
o Controls on extended vehicle idling at drive-in
facilities.
o Pedestrian malls.
o Improved bicycle facilities.
o Employer actions to support transit, carpool/van-
pool programs, bicycle usage, flexible work
schedules, etc.
127
-------
o Planning programs to assist in implementing measures
on an individual development project basis.
State Implementation Plan Consistency
Expanded wastewater treatment plant capacity for the
City of Boise and the EWSD will accommodate additional urban
development. As mentioned previously, the federal Clean
Air Act requires that federal funding programs not be used
to support projects which are inconsistent with air quality
management programs identified in State Implementation Plans.
(SIP). The SIP provides the framework for achieving and
maintaining federal air quality standards.
SIP revisions for Ada County were submitted to EPA in
January and July 1980. In October 1980 EPA approved three
aspects of the revised SIP:
o The 1979 transportation control plan portion of the
carbon monoxide attainment plan.
o A variance from state indirect source review require-
ments for the Boise Redevelopment Agency's City
Center Project.
o An extension of the CO attainment deadline from
December 31, 1982 to December 31, 1987.
EPA also required that an additional SIP revision for
Ada County be submitted by July 1, 1981. This SIP revision
is to provide commitments to, and a schedule for establishing,
an effective vehicle inspection and maintenance program.
In addition, the normal updating of the SIP (in 1982) must
include revised emission inventories and forecasts, revised
analyses of required emission reductions, and a demonstration
that "reasonable further progress" is being made toward achieving
the federal CO standards. The revised emission inventories
and forecasts must incorporate anticipated highway and redevelop-
ment projects.
The emission inventory and forecasting procedures described
in Appendix A have been developed to meet the types of require-
ments noted above. The initial application of these procedures
has been discussed previously in this chapter. These emission
forecasts were prepared using the same population forecasts
which served as a basis for the Boise wastewater treatment
facility plan.
The facility plan for the EWSD has been based on a popula-
tion forecast which is about 30 percent greater than the
forecast incorporated into the emission projections. The
analysis summarized in Table 7-4, however, indicates that
such additional development in the Eagle area would probably
128
-------
not lead to new CO problems in that planning area. This
growth increase in the Eagle area would, however, alter
traffic projections for roadways in the northwestern portion
of the Boise Metropolitan Area. It has not yet been deter-
mined whether this would significantly change the air pollu-
tion potential and emission reduction requirements listed
in Tables 7-4 and 7-5.
129
-------
Chapter 8
Groundwater Resources
-------
Chapter 8
GROUNDWATER RESOURCES
Geology
A brief discussion on geology and groundwater hydrology
is presented in this section. More detailed information
on these topics is included in groundwater and nonpoint
source waste loading reports (H. Esmaili & Associates 1980)
available in the EPA office in Boise.
Regional Geology
The regional geology of the Boise Valley is depicted in
Figure 8-1A which shows a generalized geologic cross section of
the western Snake River Plain. The western Snake River Plain
is underlain by a wide, structural trough in the granitic
Idaho batholith. This basin contains a section of upper
Cenozoic strata several thousand feet thick, composed pri-
marily of sediment and volcanics of the Idaho Group. The
stratigraphy of the Idaho Group has been classified by Malde
and Powers (1962). Overlying the eroded surface of the Idaho
Group is a relatively recent and thin sequence of basalt and
sediments into which the Boise Valley has cut. A generalized
section of the shallow geology beneath the Boise Valley is
shown in Figure 8-1B.
Geology of Study Area
Figure 8-2 is a map of the study area geology as shown by
Dion. Following is a brief description of the geologic units
exposed in the study area.
The Idaho batholith outcrops at the upper elevations of
the Northern Highland and extensively in the Eastern Upland.
The granitic batholith is generally regarded as being essen-
tially impermeable, although considerable volumes of water
are contained locally and discontinuously in fractures and
weathered zones. The fault-bounded batholith plunges deeply
beneath the Boise Valley to the southwest, forming the lower
limit of the groundwater system.
The unit of the Idaho Group which underlies the Boise Valley
is the Glenns Ferry Formation of late Pliocene and early Pleisto-
cene age. It has a thickness of about 2,000 feet beneath the
Boise Valley, outcrops extensively along the Boise Front, and
underlies much of the valley at relatively shallow depths.
Its stratigraphic subunits range in texture from clay to fine
gravel, include some volcanic ash and lava flows, and are of
highly variable thickness and extent. Bedding of the Glenns
131
-------
FIGURE 8-1
GENERALIZED GEOLOGIC CROSS SECTIONS
OF BOISE VALLEY
U)
2000
Appronmata Horizontal Scale
Varticol Scale Eiaggaratea Approximately I5x
(A) SECTION LOCATION SHOWN IN FIGURE 1
(AFTER MALDE AND POWERS, I962 )
Esmoli 1980
2000
Qolg
igMmil« Terrace / \
*• — ;-r-^_ / \ Go»en Terrace
''f-
• Qytg
Whitney T«rrace
Otg
B'
»N °'\Broodwov Ter
N
-3200'
-3000'
-2800'
Qtg
2600
Datum I* Maon Sao Laval
(B) SECTION LOCATION SHOWN IN FIGURE 7
(AFTER NACE Etol , 1957)
LEGEND- f-|
Q Qal-ALLUVIUM-CLAY. SILT, SAND & GRAVEL
0 Oyfg-LATE TERRACE GRAVEL - CHIEFLY MEDIUM-GRAIN ED TO COARSE GRAVEL W/SOME SAND.SILTE. CLAY
[it] Olb-SNAKE RIVER BASALT - GRAY TO BLACK VESICULAR BASALT ^
Ootg - EARLY TERRACE GRAVEL - CMIEFLY COARSE GRAVEL
W/SOME SAND
Otg - GLENNS FERRY FORMATION
Ki-GRANITE OF IDAHO BATHOLITH
-------
-LEGEND-
Pl.lllOt.
and
HBlgeim
Ool
CZI
Alluvium
P777I
Younger terrace grovel
Oib
Bosafl of (tie Snake River Group
Ootg
Older terrace grovel
otg
Gienns Ferry formation
of the Idaho Group
C-*"-,
Basalt of the Coluraoio River Group
Up(J(f Ki —
Critocuui i laoho Bothalith
Contact
Approxinalely located
Fault
Dashed where approximately located
Although numerous faults occur in
the Boise-Nompo area, especially
in the Boise front, onry those
referred to in this report are shovn.
Line of hydrologic section
FIGURE 8-2. GENERALIZED GEOLOGIC MAP OF
THE BOISE-NAMPA AREA
-------
Ferry Formation is inclined to the west, southwest, and south
at angles of up to five degrees in the Boise Valley region.
The formation is relatively coarser near the Idaho batholith
along the Boise Front; where exposed, it is an important ground-
water recharge area. Permeable sand and gravel beds in the
saturated Glenns Ferry Formation beneath the Boise Valley act
as an important deep, regional aquifer which is semi-confined
by the interbedded clay.
Unconformably overlying the Glenns Ferry Formation are
the deposits of terrace gravels presently exposed at the sur-
face (Figure 8-1B). Where saturated, these gravels form what is
generally referred to as the shallow aquifer of the Boise
Valley. Dion subdivided the terrace gravel deposits into
older and younger units. The older unit is described as "a
thick sheet of unconsolidated silt, sand, and well-sorted
gravel of Pleistocene age." This unit is actually a grouping
of the deposits forming the valley's upper terraces, namely
Tenmile Bench and Meridian, Gowen, and Sunrise terraces.
Deposition of these gravels appears to have occurred by streams
flowing to the southwest. The older terrace gravels range in
thickness from over 100 feet on Tenmile Bench to less than
80 feet on Meridian Terrace and generally less than 50 feet
on Gowen and Sunrise terraces.
Pleistocene to Holocene-age basalt flows of the Snake River
Group are interbedded within the older terrace gravels as well
as occurring directly over the Glenns Ferry Formation. The
basalt flow exposed on Eightmile Terrace is as much as 100
feet thick. It overlies approximately 40 feet of the older
terrace gravel. Basalt is exposed most extensively in the
study area south of Tenmile Bench and Meridian Terrace. Maxi-
mum thickness of basalt in these areas is about 150 feet.
Where saturated, the basalt has variable aquifer character-
istics. Snake River basalt is exposed over nearly the entire
Mountain Home Plateau.
Underlying the surface of Whitney and Star terraces are
the younger terrace gravels of Pleistocene and Holocene age.
These deposits of unconsolidated clay, silt, sand, and gravel,
are generally finer grained than the older terrace gravels,
and appear to have been deposited by streams flowing to the
northwest. This unit forms a thin veneer over basalt of the
Snake River Group in a large area south of Meridian Terrace.
The younger terrace gravels directly overlie the Glenns Ferry
Formation on Whitney and Star terraces where they are up to
50 feet thick.
Broadway Terrace and the tributaries of the Boise River
are underlain by unconsolidated Holocene alluvium, the young-
est geologic unit in the study area. The alluvium is composed
of silt, sand, and coarse, well-sorted gravel; these deposits
134
-------
directly overlie the Glenns Ferry Formation, and have a maximum
thickness of 50 feet. Extensive caliche development has occurred
in the alluvium and both of the terrace gravel units, as much as
10 feet thick in some areas.
Groundwater Hydrology
The Boise Valley has a unique and plentiful groundwater
resource due to the large potential storage capacity of the
recent sediments, the annual availability of large volumes of
surface water from the Eastern Upland, the distribution of
this water for recharge by way of the irrigation system, and
the occurrence of 2,000 feet of saturated Glenns Ferry Form-
ation at depth.
Boise Valley Aquifers
Previous studies have described the Boise Valley as gen-
erally having two groundwater systems—deep and shallow. The
deep groundwater system occurs completely within the Glenns
Ferry Formation. The terrace gravels, basalts of the Snake
River Group, Holocene alluvium, and upper portions of the
Glenns Ferry Formation comprise the shallow system.
The existence of a deep aquifer within the Glenns Ferry
Formation that is relatively separate from the shallow, water-
table aquifer is made evident by the difference in water
levels in wells perforated at varying depths. Water levels
in the relatively deep wells of the Boise Valley are observed
to be both above and below the level of the shallow water
table. The saturated thickness of recent sediments and basalt
in the study area range from as little as 10 feet to usually
not more than 50 feet.
The boundary between the shallow and deep aquifers within
the Glenns Ferry Formation is a gradual and poorly defined one.
Nevertheless, the cumulative effect of the occurrence of inter-
bedded fine-grained materials within the Glenns Ferry Forma-
tion is a significant reduction in vertical hydraulic con-
ductivity. In other words, groundwater deep within the Glenns
Ferry Formation, although in physical continuity with the
shallower groundwater, is being recharged and discharged in
quite a different manner from the near surface groundwater.
Wells with static water levels characteristically differ-
ent from those tapping the shallow, water-table aquifer are
ordinarily perforated at depths in excess of 300 feet, although
similar wells with shallower depths are not uncommon. Artesian
or free-flowing wells are generally located on Broadway, Star
and Meridian Terraces. Along the Boise River there are free-
flowing wells as shallow as 100 feet.
135
-------
Deep wells exhibiting water levels below the shallow ground-
water table occur primarily in the area of the upper terraces
where seasonal, irrigation-related recharge has raised the
water table to exceptionally high levels.
The saturated shallow aquifer of the Boise Valley formed
artificially as the result of agricultural development. Because
irrigation with Boise River water is not conducted south
and east of the study area, the level of the shallow ground-
water body rapidly drops to that of. the deep groundwater
system. Within the study area, the shallow aquifer contains
a principal shallow groundwater system as well as several
bodies of perched groundwater.
The shallow groundwater system is made up of five aquifer
units: the older terrace gravels, basalts of the Snake River
Group, younger terrace gravels, Holocene alluvium, and upper
portions of the Glenns Ferry Formation. With the exception of
the Glenns Ferry Formation, the components of the shallow
groundwater system act as a single hydrologic unit because
groundwater flow in this system is not significantly altered
at formation interfaces. However, each aquifer unit has a
differing range of hydraulic characteristics.
Groundwater Occurrence and Flow
The configuration of the groundwater surface in the Boise
Valley is unusually complex, reflecting the high rate of re-
charge into the shallow aquifer by diverted Boise River ir-
rigation water. The primary factors affecting the flow and
occurrence of groundwater in the Boise-Ada County Study Area
include: (1) the exceptionally high volume of recharge re-
sulting from leakage along the New York Canal, (2) the near
uniform distribution of groundwater recharge elsewhere in the
study area due to irrigation and conveyance losses, and (3) the
irregular surface of the relatively less permeable Glenns Ferry
Formation buried beneath the Boise Valley. Additionally,
groundwater is significantly influenced by bodies of buried
basalt and the system of artificial drains on the lower terraces.
The configuration of the groundwater-elevation contours
in the southwest Boise area is dominated by the influence of '
recharge from the New York Canal. The highest groundwater
elevation in the study area, 2,750 feet above sea level, occurs
beneath the New York Canal on Eightmile Terrace. The New York
Canal and other irrigation-related sources of recharge to the
west combine to produce a broad, high mound of shallow ground-
water throughout the Boise Valley. East of the New York Canal,
recharging groundwater descends quickly to the level of the deep
groundwater system.
136
-------
Within the Southwest Boise study area, high shallow
groundwater levels occur primarily beneath Broadway, Star
Whitney, Gowen, Sunrise, and Eightmile terraces. This area
is heavily irrigated and criss-crossed with leaky irrigation
canals and laterals. The resulting recharge saturates a
significant depth of the terrace gravels and alluvium. The
unusually intricate groundwater-level contours on Whitney
and Broadway terraces indicate the intersection of the
seasonal-high water table with the network of drainage canals
and laterals. To the extent that these drains are effective,
they serve to flatten the peak of the seasonal rise in the
shallow, near-surface water table.
The surface of the shallow groundwater system continues
beneath Meridian Terrace at elevations similar to the ground-
water of the lower terraces but at greater depths with respect
to the land surface. Beneath and south of Tenmile Bench and
south of Meridian Terrace, the groundwater surface declines
to the level of the deep groundwater system.
The manner and extent to which bodies of perched ground-
water in the study area become continuous with the relatively
deeper groundwater system is unclear. However, zones of
perched groundwater appear to roughly coincide with broadly
spaced water-level contours of the principal groundwater
system in both the upper and lower terrace areas. This sug-
gests an eventual merging of the perched groundwater into
the main system.
Groundwater flow. Groundwater flow patterns are distinct
for the shallow and deep aquifers. The deep groundwater
system flows from its source of recharge along the Boise Front,
Boise River, and Boise Valley in general, to the south and
southwest where it discharges to the Snake River.
The flow of the Boise Valley shallow groundwater system
originates essentially along the high recharge area coinciding
with the New York Canal. To the east of the New York Canal,
the shallow groundwater descends rapidly to the level of the
deep groundwater system. West of the canal, shallow ground-
water flow is to the west and northwest, corresponding to the
gradient of the eroded surface of the Glenns Ferry Formation
as well as the direction of deposition of the terrace gravels.
Groundwater Quality
The quality of Boise Valley water resources ranges from
generally good to excellent. Surface water from the Eastern
Upland is of highest quality, shallow groundwater and agri-
cultural drain waters have the poorest quality, and deep ground-
water is of relatively intermediate quality. The intermixing
of surface water and shallow and deep groundwater influences
their relative qualities.
137
-------
The quality of the deep groundwater in the study area is
indicated in Table 8-1 which contains the analyses of samples
obtained from 17 deep wells of the Boise Water Corporation.
When compared to the quality of the Boise River near Boise,
the deep well samples are higher in sodium (15-72 mg/1) and
dissolved solids (147 mg/1) content suggesting the impact of
recharge from irrigation return flows and wastewater disposal
operation. Nitrate concentrations (as NC^-N) range up to 10
mg/1.
Shallow groundwater in the Boise Valley is almost entirely
derived from recharge of Boise River water through irrigation
and conveyance networks. The waters immediately beneath irri-
gated agricultural lands have markedly different quality char-
acteristics than the applied water (see the analysis of the
Boise River water near Boise). Dissolved solids increase from
a range of 43 to 125 mg/1 measured in Boise River below Lucky
Peak Dam to a range of 100 to 1,240 mg/1 measured in shallow
wells. Significant increases occur in all constituents, most
notably nitrate (up to 88 mg/1 as NO^-N), sodium (up to 184 mg/1),
and chloride (up to 86 mg/1). Continual monitoring of these
shallow wells would be a prerequisite to establishing the extent
of impacts upon groundwater from irrigation, and to establishing
specific mitigation measures.
Agricultural drains exhibit water quality similar to
shallow groundwater, especially during the nonirrigation
season when no dilution occurs with irrigation return flows,
as indicated by the November analysis of Fivemile Creek drain
at Star Road (Table 8-1). Whereas the effect of agricultural
return flow is to dilute the mineral concentration of drain
water during the irrigation season, excess applied irrigation
water tends to increase mineral concentrations of shallow
groundwater due to increased leaching.
Dion (1972) investigated a possible deterioration of shal-
low groundwater quality due to land use change since the time
of the previous study by Nace, West, and Mower (1957). In-
creasingly widespread use of septic tank wastewater disposal
method was suspected to lead to a rise in nitrate concentra-
tions. However, no significant change in shallow groundwater
quality was identified. Sampling also did not reveal high
concentrations of fecal coliform bacteria in areas of septic
tank use nor a buildup of pesticides from agricultural prac-
tices.
Other investigators have continued to evaluate the possible
changes in shallow groundwater quality in the Boise Valley, again
particularly with emphasis on nitrate concentrations. A study
by the Central District Health Department (1979) showed that a
138
-------
Table 8-L. Chemical Analyses of Deep and Shallow Groundwaters,
Boise River Water, and Agricultural Drainage Waters in Boise
Valley, Idaho (in mg/1 unless otherwise indicated)
CO
Ohf-mr.-il
Oinatitviunts
Spoc . Cond .
(whos/cm)
Diss. Solids
NH-j-N
NO.,-N
NO.J-N
Oryanjc N
Total F
Ca
H',
Ha
K
Cl
S04
F
S,O-,
Tot . Hardness
Tot. Alkalinity
Total Coliform
Fecal Coliform
Fecal Strep
HCO ,h
CO,''-
Deep Groundw.iter
Eloi^e W.itor Corporal ion a
Mean
-
245
-
-
2.1
-
0.09
31
11
34
-
y.7
28
0.56
8.0
121
284
-
-
-
-
-
Variance
-
98
-
-
3.2
-
0.07
11
8.3
17
-
5.7
22
0.16
30
60
95
-
-
-
-
-
Panqe
-
147 -500
-
-
0.08- 10
-
0.02- 0.22
18 - 55
2.0 - 32
15 - 72
-
2.7 - 25
3.2 - 87
0.39- 0.75
17 - 49
57 -268
198 -548
-
-
-
-
-
Shallow <", r< ujrxlwa Lr-r
A*
Mean
970
-
0.11
0.03
11.2
0.72
0.41
-
-
-
-
15
-
-
-
-
-
-
-
-
-
—
R.ITII-JC
250 -5300
-
0 - 1.6
0 - 0 . 78
0.60- 88
0 - 2.5
0.06- 1.7
-
-
-
-
0-86
-
-
-
-
-
-
-
-
-
"
h
n
Moan
3?0
-
0.04
0.003
5.5
0.50
0.41
-
-
-
-
4.0
-
-
-
-
-
-
-
-
-
n,,,.,.
20 -950
-
0 - 0.75
0 - 0 . 1 1
0.40- 32
0 - 1.8
0.10- 0.95
-
-
-
-
0 - 15
-
-
-
-
-
-
-
-
-
n. S . Hufvui nf Reelamarinn
Slmrnum O.iks
M^an
C,78
•125
0.007
0.007
3.2
0.27
0. J4
59.4
24
61
2.0
14
59
0.97
50
-
-
318
34
16
333
0
R.,pqp
255 - 901
315 - 577
0 - O.I
0 - 0.07
0.04- 6.5
0.04- 0.88
0.02- 1.1
42 - 73
17 - 35
7 - 117
1.2 - 2.7
2.1 - 38
41 - 73
0.82- 1.1
35 - 58
-
-
2 -10200
0 - 3000
0 - 220
273 - 395
0-0
W^o.,te
Mean
748
418
0.19
0.01
5.8
0.29
0.71
59
25
70
3.6
27
59
0.68
42
-
-
72
42
35
175
0
Range ^
100 -1240
191 - 616
0 - 3.3
1 - 0.36
0.01- 24
0.02- 2.6
0.14- 6.0
28 - 85
13 - 36
4 - 184
2.0 - 5.1
0-63
28 - 85
0.44- 1.1
30 - 50
-
-
2 -1020
0 -6000
0 - 800
25 - 331
0-0
-------
Table 8-1. Cont'd.
Corr- 1 ! 1 •!. ••• 1 s
sp<~c, rr--,,-i.
( rxho^ n)
Piss. :-nli.K
N'l .-N
NO , - *•
N'l j-H
Orfi.ini'. N
Toi.il P
Cd
M.J
*1-1
K
n
S(.4
i
^ l'^2
F'^c.i I Co 1 i form
H<~O ,:i
rr. '•
J
! 5-lulIow fJroimrlwat.».T
Roi sr- Mnrrpa Ari-o
HP,™
y>6
-
-
2.7
-
0.24
-
-
-
10
-
-
-
_
_
R,ingp
104-1? 10
-
-
0- 13
-
0- 1.8
-
-
_
0- 63
-
-
-
_
_
DWH"
Moan
605
-
-
3.1
-
-
-
-
-
14
-
-
-
_
_
Var i.inco
119
-
-
2.2
-
-
-
-
-
9.8
-
-
-
_
_
Rtinqo
1U, -H(,
-
-
0.53-1 1
-
-
-
-
_
2.4-36
-
-
-
_
_
lirii-.f. Hivr-r flu. I A
3.?l.
21'J
-
_
-
-
-
-
-
-
-
3.C,
-
-
1 i vt'ini 1 11
C>». 4;
,il
?t,jr H.),vlf
r,7.1
4. in
-
_
}:\i
-
0.41
56
in
70
3. c>
14
r,2
0.7
41
'>0
322
11
L.i'l 1 r.
,-1 r .1 1 n
nrvT r
i:,i-iipr
1 (0
."'.'2
-
_
-
-
-
-
-
-
-
5.2
-
-
-
_
Pitr . I im
1 1 r a i n
nonr Afla
C'aiiynn"
<]f.O
-
0.07
0.01
3.0
0. il
0 . 30
-
-
-
-
8.5
_
_
-
-
Mosry
Crf'ek
n(-'.ir Ada
Canyon'*
540
-
0.08
0
3.2
0.36
0.18
-
-
-
-
9.4
_
-
-
_
-------
Footnotes for Table 8-1
a
Average analyses from 17 wells in study area drawing from
deep groundwater system. Range is for mean ananyses of each
well. (Boise Water Corporation, 1980) .
Area "A" north of I-bO south of Boise River and over Ada Canyon
County line. (9 wells). Area "B" along Mason creek feeder from
Hubbard Reservoir Northwest to Ada-Caynon County line.
(5 wells). Samples taken monthly 1973-1975 (Lewis et al.,
1978)--specially constructed shallow test wells.
"^Samples taken 7/77 to 9/79 (U. S. Bureau Reclamation, 1979)
Sherman Oaks: 3N1E sec- 23: 5 wells
Kestgate: 3 N1E sec. 1: 8 wells
— specially constructed shallow test wells.
d
Samples taken 6, 7, 8/70 from nearly 200 wells in Boise-
Nampa area (Ada and Canyon counties) (Dion, 1972)
£
21 wells from Idaho Department of Water Resources "Boise
Valley Monitoring Newwork" in Ada County study area.
Sampled 4/78-9/79 (Leach, 1980).
Boise River and drain. Analyses 11/71 (Thomas and Dion, 1972).
9Purdam Drain sampled 1971-1975. Mason Creek sampled 1974-1975.
(Lewis et al., 1978).
has CaCO3
141
-------
74 percent increase in nitrate concentrations had occurred since
the time of measurements made by I.1 ion, from an average of 2.02
mt/1 N03-N in June to August of 1970 to an average of 3.53 mg/1
during an undisclosed period in 1979. Preliminary results of
the Idaho Department of Water Resources' Boise Valley Monitoring
Network (Leach, 1980), however, show this increase to be well
within the range of annual fluctuations of nitrate concentra-
tions, commonly fluctuating 3 mg/1 and up to 10 mg/1 during the
year within a given well. Sampling by the U. S. Bureau of
Reclamation (1979) indicates annual fluctuations of nitrate
concentrations in wells to be commonly over 6 mg/1 and as much
as 17 mg/1. If the Idaho Department of Water Resources' data
of July 1979 is compared to Dion's data of July 1970, little
change is observed in any quality parameters (Table 8-1).
Nonpoint Source Waste Loadings of the Groundwater
Summary of Existing Nonpoint Source Discharges to Groundwater
in Ada County
Tables 8-2 and 8-3 summarize the estimated nonpoint source
loadings for Ada County and the Southwest Study Area, re-
spectively under existing land use conditions. On a county-
wide basis irrigated agriculture contributes a significant
portion of both salt (88 percent) and nitrogen (75 percent)
loadings to local groundwaters. The disposal of wastes from
feedlots and dairies in the county represents the second major
source of mineral contamination, responsible for the generation
of about 11 percent of the salt and 20 percent of the total
nitrogen discharged annually. On-site waste disposal practices
contribute relatively minor quantities of these constituents,
amounting to about 4.5 percent for nitrogen and 1 percent for
total salts.
In the Southwest Study Area irrigated agriculture is
again the major source of salt and nitrogen loadings to the
aquifer. In this case irrigation return flows contribute
84 percent of the salts and 58 percent of the total nitrogen
discharged from the three sources investigated in this study.
On-site waste disposal is responsible for approximately 11
percent of the salt load and 35 percent of the nitrogen load.
The two operating dairies generate the remaining 7 percent
of the nitrogen and 5 percent of the total salt emissions.
The figures cited in the summary tables are expressed
as total mass emissions of pollutants. As such, the values
do not reflect differences that may exist in either the con-
centration or spatial distribution of discharges. These
additional considerations may, however, have a substantial
effect upon interpretation of the results. For example, highly-
concentrated wastes from a dairy or feedlot may severely impact
142
-------
Table 8-2 Summary of Estimated Nitrogen and
Total Salt Loadings to Ground-water
from Irrigated Croplands, Animal
Husbandry and On-site Waste
Disposal in Ada County, 1980
Waste Source
On-site waste disposal
Animal husbandry
Irrigated cropland
Total
Nitrogen
tons/yr %
122
547
2058
2727
4.5
20.1
75.4
100
Salts
tons/yr %
608
6143
49334
56085
1.1
11.0
87.9
100
Table 8-3 Summary of Estimated Nitrogen and Salt Loadings
to Groundwater Resulting from Irrigated Agri-
culture, On-site Waste Disposal and Animal
Husbandry in the Southwest Study Area, 1980
Waste Source
On-site waste disposal
Animal husbandry
Irrigated cropland
Total
Nitrogen
tons/yr %
46.4
8.8
76.4
131.6
35.3
6.7
58.0
100
Salts
tons/yr %
233
109
1828
2180
10.7
5.0
84.3
100
143
-------
the quality of a downstream well, while the emission of a far
greater total mass of pollutants from cropland may have no
measureable impact because of the low initial strength of these
return flows and their large areal dispersion. Interpretation
of the data presented in this report should, therefore, be
made with an awareness of local factors which may have a sig-
nificant bearing on the relationships between pollutant dis-
charge and groundwater quality.
Impact of On-Site Wastewater Disposal Systems on
Groundwater Resources
The Southwest Boise region is a major area of concentration
of septic tank leachfield systems in Ada County. This area is
expected to remain unsewered' for the foreseeable future under
established land use plans. The major impact of septic tanks
on groundwater resources of the study area would be manifested
by high levels of nitrates and possibly total dissolved salts
and pathogenic bacteria and viruses in the shallow groundwater
bodies.
The presence of nitrate in groundwater is primarily a
result of the leaching of fertilizers from the unsaturated
soil and nitrification of organic nitrogen contributed by on-
site wastewater disposal systems and other sources. Nitrifi-
cation is an aerobic process dependent on optimal temperature
and pH conditions as well as the availability of sufficient
oxygen levels. Low concentrations of ammonia-nitrogen in shal-
low groundwater measured by the Bureau of Reclamation (1979)
(generally less than 1.0 mg/1) indicate that nitrification or
denitrification of effluent from septic tanks is occurring
primarily in the unsaturated zone. Nitrate production in the
Boise Valley is probably limited seasonally by the repeated shifts
between aerobic and anaerobic conditions due to the fluctuating
near-surface water table and by the cold winter-month soil
temperatures. The leaching of nitrate into Boise Valley ground-
water most likely occurs as the result of heavy rains, spring
snow melt and soil thaw, and the application of excess irriga-
tion water. Groundwater recharge from the infiltration of ex-
cess irrigation water not only results in the leaching of nitrate
but may also significantly dilute nitrate concentrations. Thus
seasonal peaks in groundwater nitrate concentration can be
justified theoretically at several times throughout the year
depending on a variety of complex environmental conditions.
.Mink, et al. (1975) found high levels of ammonia and coliform
bacteria in the immediate vicinity of septic tank leachfields
constructed in areas with exceptionally high water tables at
several study sites in the Boise Valley. The low values of
nitrate and nitrite concentrations were believed to be due to
the inhibition of the nitrification process by high water
table conditions.
144
-------
Nitrogen emissions in the Boise Valley are most likely
increasing as a result of septic tank wastewater disposal prac-
tices. However, annual recharge of conveyance losses and excess
applied irrigation water has the effect of diluting mineral con-
centrations to near-normal levels, particularly during the summer
and early fall months. Widespread dilution by rather uniformly
distributed excess applied irrigation water perhaps explains
the lack of well-defined high nitrate zones in the study area.
Nitrate levels may remain unchanged until the present practice
of applying an average of 3.00 acre-feet per acre per year of
excess-irrigation water of low nitrate concentration is sig-
nificantly altered. It is also probable that there exists a
trend of increasing peak-annual nitrate concentrations in
groundwater during the non-irrigation season which has gone
undetected due to infrequent sampling. An ongoing sampling
program undertaken by the Idaho Department of Water Resources
will provide the much-needed data in future years.
Groundwater Conditions and Land Use Change
Some of the previous investigations on groundwater con-
ditions in the Boise Valley were aimed at evaluating the
impact of land use changes on groundwater level and quality
characteristics. Land disposal of domestic and other waste-
waters has offset some of the losses in the historical sources
of recharge. The decline of irrigated acreage due to sub-
urbanization may have diminished the rate of recharge to
the shallow-groundwater body and caused a lowering in the
water table. Increasingly widespread use of septic tanks
as well as long-term effects of agriculture have been
expected to result in groundwater quality degradation.
No significant changes in groundv/ater quantity and quality
conditions were observed in the Boise-Nampa area between 1953
and 1970. The explanation given for a lack of change in shallow
groundwater levels were as follows: (1) the magnitude of change
in recharge and discharge were relatively small, (2) seasonal
and year-to-year fluctuations in water-supply conditions over-
shadowed any progressive changes in groundwater conditions
with time, and (3) small changes in the level of near-surface
water tables were moderated by the influence of artificial
drains.
Results of the present study tend to indicate the existence
of a correlation between the quality of shallow groundwater
body and the volume of recharge from irrigation water distri-
bution network and cropped land areas. It appears that recharge
from these sources helps to dilute the waste loadings derived
from agricultural, residential and commercial land use practices.
As additional agricultural lands are converted to nonagricultural
uses, the balance between nitrogen and salts loadings and the
volume of water recharged to the aquifers will be adversely
affected.
145
-------
Even after suburbanization changes, significant volumes
of Boise River irrigation water are being recharged to the
groundwater by irrigation of landscaped areas. On the other
hand, the continued trend of lining the irrigation canals and
laterals \vil 1 significantly reduce shallow groundwater recharge.
Reduced shallow groundwater recharge will undoubtedly result
in lower water tables and a shift in the shallow groundwater
divide, possibly to the west away from the New York Canal.
Lowering of the water table will place groundwater of rela-
tively poorer quality nearer to the zone in which the main
water" supply wells are located. Additional long-term moni-
toring of groundwater levels and quality conditions must be
carried out to provide adequate data for evaluating the impact
of land use changes in the study area.
Mitigation Measures
Under land use Plan C, Rural Life Style, it is expected
that the Southwest Boise area will retain its rural charac-
teristics for the foreseeable future. Although some popula-
tion growth is expected to occur in this area over the next
20 years, it is improbable that the anticipated growth will
create a major change in groundwater quality and quantity
conditions, barring any significant unforeseen changes in
other land use practices or in the irrigation practices of
local farmers.
Based on the above discussion, no specific mitigation
measure is deemed necessary to alleviate the adverse impact
of septic tank discharge on groundwater quality in the study
area. Regular monitoring of shallow and deep groundwater
quality, preferably on a seasonal basis, should, however, be
carried out by an appropriate government agency to provide
needed data for future planning and decision-making purposes.
Also, adequate controls should be maintained on siting, design,
installation and maintenance of septic tank and leachfield
systems to assure the protection of public health and safety.
A draft document prepared by the Ada Planning Association
(APA 1980) contains a comprehensive plan which could provide
the basis for developing a workable on-site waste disposal
management program.
The elements of the proposed plan are as follows:
Identification of portions of rural Ada County with
high septic system failure rates and comparison of
characteristics of such areas to determine causes of
the failures.
Modification of design criteria established by the
Central District Health Department to decrease the
number of septic system failures due to identified
study area characteristics.
146
-------
Establishment of a map of rural Ada County that
indicates locations of septic system failures.
The map would be continually updated to include
locations of new failures (map contained in the
September 1980 version of the draft APA report
[APA 1980]).
Establishment of a coordinated groundwater monitoring
program
Development of a public education program for resi-
dents and commercial establishments
Development of a voluntary/mandatory maintenance
program
Establish a user fee schedule to fund the program.
Discussions of some of these plan elements, especially the
maintenance program, may be found in the September 1980 ver-
sion of the APA document.
Impacts of Sludge Disposal
on Groundwater Resources
Boise Sludge Disposal Site
Land at the Idaho State Penitentiary is considered to
be the preferred site for sludge disposal. Soils mapping
of the site was conducted by the SCS and soil suitability
ratings for sludge application were identified.
The surveys showed that much of the area was underlain
by a hardpan layer, ranging from 13-34 inches below the surface,
The water table is located below the hardpan layer, at an
unknown depth. The SCS survey indicated a depth to ground-
water of ,'72 inches, while other SCS data indicated depths
to the seasonal high water table ranging from 24-60 inches
(CH2M Hill 1980b). An irrigation well on the site is known
to draw water from a depth of 550 feet.
The presence of the hardpan layer between the surface
and the groundwater should prevent the movement of leachate
downward. Because it is unlikely that the hardpan layer
occurs uniformly throughout the area, leachate could travel
downward toward the water table wherever cracks or breaks
in the hardpan occur.
During the rainy season water may perch above the hard-
pan and move laterally downslope. Much of the sludge appli-
cation site is flat or has slopes of 3 percent or less.
147
-------
The migration of heavy metal ions into the groundwater
should not occur so long as the soil and sludge pH is main-
tained above 6.5 (1977a).
Surface ponding of liquid sludge may increase mosquito
populations. Pathogens from the sludge may be transmitted
by insect or rodent vectors or by aerosols. Sludge has the
potential to cause odors in the area of application.
Sludge has the potential benefit of fertilizing crop
lands with a product otherwise buried in. landfill or unavail-
able. This also has potential benefits of possible revenue
to the City of Boise through sale of sludge, and of reduced
costs to the farmer.
Mitigation Measures
The IDHW has prepared Guidelines for Land Application
of Municipal Sewage Sludge which include a number of features
designed to protect groundwater resources:
Site approval requires demonstration that the
proposed project will not result in violation of
water quality standards applicable to ground and
surface water (Idaho Department of Environmental
and Community Services, 1973). Factors that will
be considered in granting approval include:
- Proximity to water supply wells.
- Existing quality and use of groundwater.
- Geohydrological characteristics of the site; the
minimum groundwater depth should not be less
than 4 feet.
Monitoring wells should be installed as indicated
by a geohydrological study of the site. The wells
and surface streams in the areas should be analyzed
for nitrogen, heavy metals, organic and fecal
coliforms before sludge disposal at the site and
during the life of the project.
Mosquito population may be limited by reducing surface
ponding and by using mosquito control measures as necessary.
Pathogens in the sludge are not expected to be signifi-
cant, however opportunities for exposure to humans should
be reduced by limiting access such as by fencing and by "buffer
zones". The site is already on prison land and public access
reduced accordingly.
Spraying should be avoided on windy days in order to
eliminate drift of liquid or aerosols from the application
area.
148
-------
Odors may be mitigated by "buffer zones" between the
treated area and human use areas. Additional measures such
as'working the sludge into the soil may be required as
necessary -
Eagle Water and Sewer District Disposal Site
The location for disposal of sludge from the Eagle waste-
water facility has not yet been determined. Land application
could be utilized with Alternative A - Oxidation Ditch, Alter-
native C - Land Application by Irrigation, Alternative D -
Rapid Infiltration. With Alternative B - Pump to West Boise
Treatment Plant, sludge would be disposed of on the Boise
application site.
149
-------
Chapter 9
Hydrology and Surface Water
Quality
-------
Chapter 9
HYDROLOGY AND SURFACE WATER QUALITY
Existing Conditions
Hydrology
The main watercourse in the study area is the Boise
River. The Boise River flows westerly for about 200 miles
from its headwaters in the Sawtooth Mountains to its confluence
with the Snake River, draining a watershed area of 4,234
square miles (Figure 9-1).
Peak flows in the Boise River occur during the spring
snowmelt period between April and June. High flows of short
duration occur due to summer thundershowers. Minimum flows
occur during the winter months. During the winter when there
is no demand for irrigation water, runoff is generally stored
in reservoirs.
River Regulation. The Boise River is regulated by three
on-stream reservoirs (Lucky Peak, Arrowrock, and Anderson
Ranch) and one off-stream reservoir (Lake Lowell). Various
direct diversions along the Boise River also regulate the
flow. The four reservoirs and their storage characteristics
are shown in Table 9-1.
Lucky Peak was the most recent dam to be constructed
on the Boise River system. Storage capacity in Lucky Peak
has been allocated (Table 9-2) to irrigation and to the Idaho
Department of Fish and Game for flow maintenance during the
nonirrigation season..
Lucky Peak Reservoir is operated in conjunction with
Arrowrock and Anderson Ranch to maximize irrigation, flood
control, power production and recreation benefits.
The unallocated storage in Lucky Peak (Table 9-2) was
set aside for future irrigation needs. Demand for this capacity
from newly irrigated lands, however, has not occurred. Irri-
gation districts have the right to purchase some of the capa-
city on a year-to-year basis if their supply falls short.
A cooperative study of reservoir operations on the Boise
River system is currently being conducted by the Idaho Department
151
-------
en
NJ
PAYETTE .
SOURCE: IDAHO WATER RESOURCES BOARD, 1974
LOCATION MAP
FIGURE 9-1. BOISE RIVER WATERSHED
-------
Table 9-1. Principal Reservoirs
in the Boise River Basin
Reservoir
Capacity (AF)1
Gross Active
Year Constructed
Agency
Water Source
Anderson
Arrowrock
Lucky Peak
Lake Lowell
493,
286,
307,
190,
200
600
040
100
423
286
266
169
,200
,600
,200^
,000
1945-USBR2
1915; raised 5 ft.
in 1937- USER
1954-USCE
1908-USBR
South Fork,
Boise River
Boise River
Boise River
New York Canal
(Boise River)
NOTES:
•"•AF: acre-feet.
2USBR: U. S. Bureau of Reclamation (now the U. S. Water and Power Resource Service)
3USCE: U. S. Array Corps of Engineers.
l*278,200 AF available (top 4 feet of storage not used).
SOURCE CH2M Hill 1980b.
-------
Table 9-2. Lucky Peak Reservoir Storage Allocation
Total Capacity Usable Capacity
Use (AF) (AF)
Irrigation 111,750 107,200
Idaho Department of
Fish and Game 50,000 47,800
Unallocated 116,250 111,200
TOTAL 278,000 266,200
SOURCE: CH2M Hill 1980b.
154
-------
of Water Resources, the U. S. Army Corps of Engineers, and
the U. S. Water and Power Resources Service (WPRS). A second
study, which will assess the uncontracted capacity in Lucky
Peak Reservoir, is being conducted by WPRS (CH2M Hill 1980b).
The results of these studies may have significant bearing
on the Boise River flows available to dilute Boise sewage
effluent. The WPRS study is not expected to be complete
until 1982.
Flooding. Flooding has historically occurred on the
Boise River during spring runoff and thunderstorms. The
frequency of flooding, however, has decreased as the degree
of river regulation has increased. The highest recorded
flood flow occurred in 1896 when 35,500 cubic feet per second
(cfs) was measured at Boise. The largest rainfall-related
flood was recorded in 1909 at 15,200 cfs.
The Boise River is currently regulated so as not to
exceed a flow of 6,500 cfs in Boise. Flooding occurs within
the Boise Metropolitan area at flows exceeding channel capa-
city of 6,500 cfs. Major flooding generally occurs at flows
over 10,000 cfs.
Flood control operations at the reservoirs begin in
January and usually continue through May, when storage begins
in the empty flood control capacity.
Irrigation. The greatest use of surface water in the
Boise River watershed is for irrigation. Irrigation in the
Boise Valley dates from the late 1800s. Currently, there
are 31 major irrigation diversions from the Boise River.
These canals have a total capacity of 6,700 cfs (Idaho Water
Resources Board [IWRB] 1974). A transbasin diversion from
the South Fork of the Boise River occurs at Little Camas
Reservoir. This diversion, averaging 10,500 acre-feet per
year, is used for irrigation of lands in the Mountain Home
Irrigation District, outside of the Boise River watershed.
Flow Conditions. The flows of the Boise River vary
significantly between Lucky Peak Dam and the mouth of the
river. Hydrographs representing the flow in the Boise River
at various locations are shown in Figure 9-2. During the
irrigation season significant flow reductions occur between
Lucky Peak Dam and Capitol Street Bridge. Between Capitol
Street and Star, the flow is reduced even more due to addi-
tional diversions. At Parma, return flows have added to
the river and increased the flow.
Calculated natural annual flow (with no dams or diversions)
and impaired flow (with existing dams and diversions) below
Lucky Peak Reservoir, and l-in-2 year and l-in-10 year flows
at Boise are shown in Figure 9-3. As a result of regulation
and diversion, flows are much lower than natural, especially
155
-------
4200 -i
3400 -
ifinfi
o
o
UJ
CO
iii 99nn
M LU
Ul u-
o
" 1 8UU
:=>
o
1000
600 -
200 -
«
\
I
\
\
\
\
t
•"' s
___,
=
\
t
i
t
\
\
^
i
\
\
\
s
— —
- LEIGEIND-
BELOW LUCKY PEAK
CAPITOL (BOISE)
STAR
\
\
::t^\
X
'>
*
f
^— — ^— ^—
^
* " •«.
t
\
\
\
•^^ _ •_— -^-^— -—-———
•^^— ^— ^^^^— ^
' "
i— : LJ -• — -_• -•-•—-
===== ===== ===== ===== === — .
AUG SEP OCT NOV DEC JAN
1972
FIGURE 9-2. AVERAGE MONTHLY FLOW AT
(AUGUST 1972 THROUGH JULY 1973)
'
_ ... i —~
y
1
1
1
/
1
/ ^
/
•^ -.•-I-.'P-I- -- - _
f
1
/
t
1
I
1
1
1
/
/
~\
1 " ——
*''
— — — .
i" .— fr^^^^^^r^
~"^-
_.
\
^^
FEB MAR APR MAY JUN JUL AUG
1973
SOURC: ACOG 1975 & IDWR DATA
FOUR LOCATIONS ON BOISE RIVER-
-------
10,000-
5,000-
1,000-
0
z
o
Ju 50'0-i
eo
Q£
LU
Q-
t—
LU
LU
O
m
0 inn
z
o
^J
•*- 50-
J A-
5-
— - -
t==^=
J/
^==~-
1
1
1
i
1
l
1
1
1
'•-"""
/
- ..-_^nx-,_--- —
N FE
/
/
^_ H
.•
/
,•
-- '
^^^^=^=
B Ut
i
/
/
/
/
/ 1
/
:
\l :
~
.
."
;
•
/^
1
i
i
i
i
i^
i
i
i
i
i
•
i
^=^^^=
IR Al
^
,*
/
/
/
1
— ^
^^d
—
..
*.
'•
****
t "
I
J^\ IN 2 YEAR MONTHLY AVERAGE
i,^^^^
v
V-
\
\
•..
'•••
NATURAL FLOW BELOW LUCKY PEAK
* "^-^
i
\
\
-A
^ ^ A
"^
-^
>
1 IN 2 YEAR MONTHLY
AVERAGE IMPAIRED FLOW
AT BOISE
-.
\
WJ 1 IN 10 YEAR MONTHLY AVERAGE
7 IMPAIRED FLOW AT BOISE
=^=^^=
>R M;
\Y Jl
JN Jl
JL Al
s
JG
MONTH
SI
J
^^"
\
\
\
\
\
\
% •.
\\
i
i
i
V
1
t
\
1
EP 01
1 IN 2 YEAR MONTHLY
AVERAGE IMPAIRED FLOW
BELOW LUCKY PEAK
i_ j
\
\
\
\
\
\ \
'•'. \
\
>
t
\
\
i
\
_, -
^
t
;T N(
• — ••
)V Dl
^^^^^^—2
:c
s^^^m
=
=^
(US6S DATA, U.S. ARMY CORPS OF ENGINEERS DATA) YEARS OF RECORD 1988-1979
FIGURE 9-3. HYDROLOGIC CHARACTERISTICS OF THE BOISE
RIVER BELOW LUCKY PEAK DAM AND
157
AT BOISE
-------
during the nonirrigation season (November-March) . The 1-
in-10 year low flow at Boise during the nonirrigation season
is lower than the l-in-2 year flow by about a factor of 10,
while the difference during the irrigation season is much
less. The greater difference during the nonirrigation season
is partially due to periodic maintenance shutdowns of the
Lucky Peak outlet structure. The periodic shutdowns will
probably cease when the hydropower facilities proposed by
the Boise Project Board of Control are installed in Lucky
Peak Dam.
Regulation of the Boise River by all the dams now in
place began in 1955, but the operation of those reservoirs,
especially Lucky Peak, has changed recently- The current
regulation scheme, begun in 1977, balances water allocations
so that any shortages in storage in Lucky Peak Reservoir
will be taken in the unallocated storage rather than the
allocated irrigation or fish and game storage. That is,
if Lucky Peak fails to fill, the deficit will be assigned
to the unallocated capacity first. Past practice was to
distribute the shortfall over all three storages.
Existing Treatment Plant Flows. There are three waste-
water treatment plants in the Boise Metropolitan area. There
are also treatment plants at Eagle and Caldwell.
Lander Street and West Boise sewage treatments plants
serve the Boise Metropolitan area and discharge directly
to the Boise River, adding to river flows. Lander Street
has a design flow of 15 million gallons per day (MGD) (22.5 cfs)
and West Boise is designed for 6.3 MGD (9.5 cfs). Gowen
Field, located at the airport, is designed for 0.5 MGD and
discharges to land. The Lander Street plant is operating
at capacity. The West Boise plant is overloaded hydraulically
in summer due to excess infiltration/inflow (CH2M Hill 1980c).
The Eagle plant has a design capacity of 0.3 MGD for summer
and 0.5 MGD for winter (J-U-B Engineers 1980).
Water Quality
Water Quality Standards. Designated beneficial uses,
water quality standards, and wastewater treatment requirements
in Idaho are promulgated by the State of Idaho in Title 1,
Chapter 2 of the Rules and Regulations of the Idaho Department
of Health and Welfare. These rules and regulations are formu-
lated by department staff, and adopted by the Board of Health
and Welfare pursuant to authority vested by the Idaho code.
Within 1 year of adoption by the board, the Idaho State
Legislature may modify or reject new or revised rules and
regulations by concurrent (majority) resolution of both houses.
The EPA may approve standards set by the state, or not
approve them and promulgate its own standards. EPA formulates
National Pollutant Discharge Elimination System (NPDES) permit
requirements (i.e., waste discharge permit requirements) to
158
-------
comply with state standards it approves, or its own standards.
EPA may take enforcement action against dischargers in vio-
lation of NPDES permit requirements.
Idaho Designated Beneficial Uses. Beneficial uses desig-
nated for the Boise River basin below Lucky Peak Dam are
shown in Table 9-3. Above river mile 50 (the location of
the Lander Street sewage treatment plant discharge) the river
is protected for all uses, and is designated a Special Re-
source Water. Below river mile 50, domestic water supply
and special resource water designations are dropped.
In addition to protection of specifically listed desig-
nated beneficial uses in specific waters, the rules and regu-
lations state that protected uses are not limited to those
listed uses; and that "in all cases, existing beneficial
uses of the waters of the state shall be protected" (Section
1-2050.026).
Idaho Standards for Protection of Benef-La-Lai Uses. The
water quality standards for protection of beneficial uses
are shown in Table 9-4. The standards for a given use apply
to waters protected for that use, unless superseded elsewhere
in the regulations. For example, the dissolved oxygen standard
for salmonid spawning in the Boise River below river mile
50 (the Lander Street discharge) is lowered to 6 mg/1 or
75 percent of saturation, whichever is greater, by Section
1-2278 of the regulations.
In late March 1980, the Idaho legislature revised the
un-ionized ammonia standard for Indian Creek below Nampa
to 1.0 mg/1. The legislature has also lowered the dissolved
oxygen standards below reservoirs from 6 mg/1 to 5 mg/1.
Water Quality Conditions. The water quality conditions
of the Boise River and its tributaries have been extensively
studied since the early 1970s. Sampling has included dissolved
and suspended constituents, bacteria and the biotic communities.
Sampling agencies have included:
o Ada Planning Association
o U. S. Water and Power Resources Service
o City of Boise
o Boise State University
o Idaho Department of Health and Welfare
o U. S. Army Corps of Engineers
o Idaho Department of Fish and Game
o U. S. Environmental Protection Agency
o U. S. Fish and Wildlife Service
159
-------
Table 9-3. Protected Beneficial Uses of Waters of the
Boise River Basin Below Lucky Peak Dam
Beneficial Uses
River Reach
Domestic
Water
Supply
Agricultural Cold Warm Prdjmary Secondary Special
Water Water Water SaLronid Contact " Contact Resource
Supply Biota Biota Spawning Recreation Recreation Water
Boise River - Lucky Peak
to River Mile 50 (through
Veterans State Park)
Boise River - River Mile
50 (Veterans State Park)
to Caldwell
Ten Mile Creek
Five Mile Creek
Boise River - Caldwell
to mouth
Indian Creek - Above
Sugar Avenue, Nampa
Indian Creek - Below
Sugar Avenue, Nampa
• Protected for present use.
* Protected for future use.
i
Except Lucky Peak Dam to Diversion Dam.
SOURCE: Title 1, Chapter 2, Rules and Regulations of the Idaho Department of Health and Welfare.
-------
Table 9-4. Summary of Idaho State Water Quality Standards
For Designated Beneficial Uses
Use
Primary Contact
Recreation
Secondary Contact
Recreation
Cold Water Biota
Parameter
Standard
Fecal coliform
(May 1-Sept. 30)
Fecal coliform
Dissolved oxygen
PH
Temperature
Total Dissolved Cases
Un-ionized NH_
<_500/100 ml any sample
<_50/100 ml 30-day geometric mean
1800/100 ml any sample
<_200/100 30-day geometric mean
> 6 mg/1 at all times
6.5-9.0
<22°C instantaneous; <19°C daily average
<110 percent of saturation
<0.04 mg/1 30-day mean if water quality
characteristics near optimal, <0.02 mg/1
otherwise
Salmonid Spawning
(During Spawning
and Incubation)
Domestic Water
Supply
Dissolved oxygen
pH
Temperature
Total Dissolved Gases
Un-ionized NH
Arsenic
Barium
Cadmium
Chromium
Cyanide
Fluoride
Lead
Mercury
Nitrate
Selenium
Silver
Endrin
Lindane
Methoxychlor
Toxaphene
2,4 D
2,4,5, TP with Silvex
>6 mg/1 or 90 percent saturation, whichever greati
6.5-9.0
<13°C instantaneous; <9°C daily average
<110 percent of saturation
<0.04 mg/1 30-day mean if water quality
characteristics near optimal; <0.02 mg/1
otherwise
< 0.05 mg/1
< 1 mg/1
< 0.01 mg/1
< 0.05 mg/1
< 0. 2 mg/1
< 2. 4 mg/1 (< 12°C)
< 2. 2 mg/1 (12.1-14. 6°C)
< 2.0 mg/1 (14.7-17.6°C)
< 1.8 mg/1 (17.7-21.4°C)
<1.6 mg/1 (21.5-26.1°C)
< 1.4 mg/1 (26.3-32. 5°C)
< 0.05 mg/1
< 0 . 002 mg/1
< 10 .0 mg/1 as N
< 0.01 mg/1
< 0.05 mg/1
< 0.0002 mg/1
< 0.004 mg/1
< 0. 1 mg/1
< 0.005 mg/1
< 0. 1 mg/1
< 0 . 0 1 mg/1
NOTES:
For more detailed information concerning standards and sampling requirements, consult the
rules and regulations.
SOURCE: Section 1-2250, Rules and Regulations of the Idaho Department of Health and
Welfare.
161
-------
Water quality conditions are governed by various point
source discharges, by agricultural return flows and by river
flow available to dilute pollutant loads. During the winter
nonirrigation season, flow in the river below Lucky Peak
is often insufficient to provide adequate dilution of wastes
discharged to the river. In the irrigation season, diversion
of flow for agricultural usage may create low flow conditions
in the vicinity of Star. Below Star flows again increase
due to agricultural return flows.
Water quality conditions for the Boise River are given
in Table 9-5. Generally, the water quality of the Boise
River worsens downstream of Boise. This degrading condition
is due to the various point and nonpoint source pollutant
loads entering the river. Several industrial discharges,
in addition to the municipal waste load, add significant
pollutant loads. Agricultural drains also account for a
portion of the total pollutant load in the river.
Temperature. The temperature of the Boise River in-
creases in downstream direction and is especially elevated
during the summer months. An increase in water temperature
occurs between Caldwell and Parma stations, which have average
summer temperatures of 14.9°C and 17.4°C, respectively. The
flows in this reach are governed by agricultural return flows.
Dissolved Oxygen. Adequate levels of dissolved oxygen
are necessary for the survival of fish and other aquatic
organisms. STORET (EPA computerized data base) data show
that dissolved oxygen concentrations in the Boise River
decrease in a downstream direction during the summer months.
During the winter the average dissolved oxygen is relatively
stable, with only a slight decrease downstream. The agricultural
drains usually have lower dissolved oxygen concentrations
than the Boise River.
Ada Council of Governments (AGOG 1975d) found dissolved
oxygen concentrations to decrease in a downstream direction.
The concentrations, however, were determined to be within
acceptable limits for the beneficial uses along the river.
At Star, EPA (1971a) found minimum percentage dissolved
oxygen saturation. Star is the point in the river where
flows are greatly reduced, often approaching a no-flow
condition.
Nutrients. The major nutrients used by algae and other
aquatic plants include various nitrogen and phosphorus com-
pounds. Nitrogen released in sewage effluent is primarily
in the form of organic nitrogen or ammonia. Various bacteria
decompose the organic nitrogen to ammonia, while other bacteria
162
-------
Table 9-5. Average Water Quality Conditions
of the Boise River Main Stem
CTi
U)
Boise River
Below
Lucky Peak
Boise River
Below
Barber Dam
Boise River Boise River Boise River
At At at Highway 30
Glenwood Bridge Star Bridge, Caldwell
pH (units)
Temperature (°C)
DO (mg/1)
BOD (mg/1)
Ammonia -N (mg/1)
Nitrite -N (mg/1)
Nitrate -N (mg/1)
Organic
Nitrogen -N (mg/1)
Total Phosphorus
-P (mg/1)
Ortho Phosphorus
-P (mg/1)
s*
7.3
11.9
10.1
1.1
.02
< .01
.12
.28
.04
.01
W*
7.3
7.3
11.6
1.2
.02
.01
.23
.26
.06
.03
S
7.2
12.0
9.6
1.2
.02
< .01
.12
.28
.04
.01
W
7.3
7.2
11.8
1.1
.02
< .01
.16
.25
.05
.02
S
7.4
12.7
9.4
1.4
.20
.02
.19
.29
.19
.14
W
7.5
7.3
11.2
2.7
.43
.03
.32
.36
.31
.23
S
7.4
14.3
9.5
1.9
.04
.02
.37
.38
.17
.12
W
7.5
7.3
11.1
2.5
.20
.03
1.07
.41
.39
.30
S
7.7
14.9
8.7
1.8
.03
.02
.86
.50
.26
.15
W
7.8
7.5
11.4
2.2
.10
.05
1.60
.43
.33
.22
*S = summer, April-September
W = winter, October-March
SOURCE: STORET (data collected by U. S. Water and Power Resources Service, mainly from
1977-1979).
-------
convert ammonia to nitrite and nitrate. Algae can use ammonia,
nitrite, or nitrate; the nitrate form, however, is most readily
used. While ammonia and nitrite can serve as plant nutrients,
these two forms of nitrogen can also be toxic to fish.
Very little ammonia is found in the river above Boise.
Ammonia concentrations reach a maximum (0.43 mg/1 in winter)
at Glenwood Bridge. The increase is due to wasteloads,
especially treated municipal sewage, entering at Boise. Below
Boise, the river shows improvement with the ammonia concen-
trations decreasing (EPA 1971a, AGOG 1975d). Nitrate increases
in a downstream direction, with the highest concentrations
found at Parma. The large nitrate concentration at Parma
is due not only to upstream discharges of ammonia, organic
nitrogen and nitrite from wastewater effluent, but also
due to runoff from agricultural lands.
Total phosphate and orthophosphate increase in a down-
stream direction. Orthophosphate averages 0.01 mg/1 below
Lucky Peak and 0.30 mg/1 at Star. The increase is primarily
in response to runoff from agricultural acreage or accretions
from groundwater recharge from irrigation and treated sewage
effluent.
Biochemical Oxygen Demand. Biochemical oxygen demand
(BOD) is an index of the oxygen-consuming organic substances
in water. High BOD levels can deplete the dissolved oxygen
necessary for survival of fish and other aquatic organisms.
The BOD in the Boise River does not show large increases
over upstream concentrations until the station at Parma.
During summer conditions, organic materials are readily oxi-
dized. Consequently, the effect of oxidizing BOD loads shows
up at lower oxygen concentrations rather than increased BOD
concentrations. In the winter, colder temperatures inhibit
the organisms that oxidize organic material, and BOD increases
at the downstream stations.
Present Effluent Effects. Water quality data are collected
above and below both the Lander Street and West Boise outfalls.
Summer average data are shown in Table 9-6. Increases in
ammonia and phosphate occur below the Lander Street outfall,
while dissolved oxygen concentrations decrease. Temperatures
increase slightly. The change in river quality due to the
West Boise discharge is not as pronounced for many consti-
tuents as at the Lander Street plant. Phosphate levels show
the greatest relative increase.
The Eagle wastewater facilities have met NPDES permit
requirements with the exception of suspended solids during
algal blooms in the treatment ponds (J-U-B Engineers 1980).
164
-------
Table 9-6. Average Water Quality Data Above and Below
Lander Street and West Boise Sewage Treatment
Plant Outfalls, October 1975-April 1980
Above
Lander St.
Temp . ° C
PH
Dissolved O_ mg/1
NH--N mg/1
J
PO. mg/1
~r
I
N
I
N
I
N
I
N
I
N
10.
6.
7.
7.
9.
10.
0.
0.
0.
0.
6
0
4
5
9
2
12
22
22
23
Below
Lander St.
10
6
7
7
9
9
0
0
0
0
.8
.7
.4
.5
.3
.5
.34
.94
.47
.85
Above
W. Boise
11.
6.
7.
7.
9.
8.
0.
0.
•
•
8
4
5
6
0
7
12
50
34
72
Below
W. Boise
11
6
7
7
8
9
0
0
1
.5
.6
.5
.6
.9
.5
.09
.43
.43
.04
NOTES:
I = Irrigation season (April-September)
N = Nonirrigation season (October-March)
SOURCE: City of Boise (Lander Street Wastewater Treatment Plant file
data).
165
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Impact Analysis
Hydrologic Changes
The Lander Street and West Boise sewage treatment plants
are projected to treat and dispose of an annual average of
34.9 MGD of wastewater by the year 2000. The projected division
of flow between the two plants is projected to be as follows
(including the Southwest Area):
Flow
Irrigation season
Nonirrigation season
Lander St.
(MGD)
11.7
9.0
West Boise
(MGD)
27.7
21.2
Total
(MGD)
39.4
30.2
SOURCE: CH2M Hill 1980c.
The effluents from both treatment plants will discharge
to the Boise River, adding to the existing river flows. Table 9-7
shows low flow conditions projected for the Boise River under
current reservoir management procedures; projected sewage
discharges are included in these values. The Eagle effluent
(1.0-1.3 MGD) will not significantly affect these values.
An indirect impact on flow in the Boise River in the
future will be increased storm peak flows due to increased
stormwater runoff. Increased stormwater runoff is not directly
caused by the treatment plants; it is caused by growth of
population, urbanization, and impervious surface that follow
expansion of the plant and sewer service. This secondary
impact will increase the storm peak flows in storm drain
channels and possibly the Boise River.
Water Quality Changes
The facilities planning has been conducted assuming
a l-in-10 year low flow of 80 cfs below Lucky Peak. As dis-
cussed in the facilities plan (CH2M Hill 1980c), this flow
value assumes that reservoirs on the Boise River will be
operated in the same manner as they have been for the past
2 years. The historical l-in-10 year low flow, which is
normally the design parameter for sewage treatment facilities,
is 0 cfs below Lucky Peak. This is due to shutdown of the
reservoir outlet for maintenance. This should no longer
be a problem when the Boise Project Board of Control installs
a second outlet for its hydropower facilities.
166
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Table 9-7. Projected Fall and Winter Low Flow
Conditions in the Boise River
Season
Percent Probability Return
that Flow will be Period
Equalled or Exceeded (years)
Flow Below
Lucky Peak
(cfs)
Flow Below W. Boise
Assuming High or
Low Groundwater
Inf1ows (cfs)
Low2
CTl
Fall conditions
Winter conditions
16
11
10
9
8
10
12
11
10
9
8
6
9
10
11
13
6
8
9
10
11
13
225
100
80
70
60
150
100
90
80
65
50
NOTES:
1High groundwater inflow = 25 cfs. both fall and winter.
2Low groundwater inflow = 13 cfs in fall, 6 cfs in winter.
297
172
152
142
132
221
172
162
152
137
122
285
160
140
130
120
203
153
143
133
118
103
SOURCE: Barker, CH2M Hill pers. comm.
-------
However, it is a problem to assure that there will actually
be a full 80 cfs available as a l-in-10 year low flow. Much
of the water released in the nonirrigation season from Lucky
Peak Dam comes from the unallocated storage. This water
has been appropriated by the U. S. Water and Power Resources
Service, and is subject to sale to irrigators. There appears
to be no demand for this water on irrigable lands in the
Boise Valley. There may be a future demand in the Mountain
Home area, and the water may go there via transbasin diversion..
The City of Boise and the facilities planners are con-
tinuing efforts to assure the minimum flows at least through
the life of the project (year 2000) . These efforts will
probably not be resolved until the U. S. Water and Power
Resources Service completes its operations studies of the
Boise River system sometime in 1982. If flow assurance is
obtained, then the Lander Street plant will be able to
operate without violating water quality standards at the
l-in-10 year flow. At less frequent flows (1-in-ll years,
l-in-12 years, etc.), the receiving water ammonia standard
would be violated. Residual chlorine standards violations
will probably cease to be a problem because dechlorination
will be added to the Lander Street process train. If flow
assurances are not obtained it is uncertain what actions
the facilities planners and EPA will take.
The West Boise plant is being designed to meet receiving
water quality standards (CH2M Hill 1980c) at river flow levels
present in the receiving waters. Low flow releases from
Lucky Peak Dam are not an issue. The West Boise plant will
be able to convert ammonia to nitrate through the nitrifica-
tion process. The Lander Street plant does not have enough
land area available to install nitrification processes that
are economical. The expansions to the West Boise facilities
are not anticipated to cause water quality standards violations.
The pollutant loading from the West Boise treatment
facility will increase with the exception of residual chlorine,
which will decrease because dechlorination will be installed.
Assuming expansion of the existing plant to an annual average
effluent flow of 15 MGD, the pollutant loading will increase
approximately 150 percent. Construction of the second plant
to accommodate a total effluent flow of 24.45 MGD will mean
an increase in total loading of 310 percent over existing
conditions.
The increase in pollutant loading after plant expansion
may impact downstream areas in several ways. The dissolved
oxygen decrease downstream from the plants will probably
be larger due to greater BOD loadings. Higher nutrient
loadings (nitrogen and phosphorus) may cause higher algal
168
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growth levels, which may cause larger variations in existing
diurnal dissolved oxygen. It is not known whether increases
in diurnal dissolved oxygen variation will be great enough
to affect fish and other aquatic life.
The expanded Eagle wastewater facilities are being de-
signed to meet discharge requirements and protect water quality
in the Boise River. No adverse impacts on Boise River water
quality are foreseen.
Construction Impacts
Construction of expanded sewage treatment facilities
and interceptor lines in Boise and Eagle will result in short-
term local increases in erosion and sedimentation in the
vicinity of the construction sites. The Eagle interceptor
will cross several watercourses. The south Boise interceptor
route alternatives that run along the Boise River appear
to have greater sedimentation impact potential than the inland
east route (CH2M Hill 1980c).
Mitigation Measures
The main unresolved issue concerning water quality impacts
on the Boise River is obtaining an assurance of a l-in-10
year low flow of 80 cfs from Lucky Peak Dam. The l-in-10
year low flow is fundamental information that is basic to
designing a sewage treatment process train that is sufficient
to protect receiving water quality. The design criteria
for the Lander Street plant modifications hinge on a l-in-
10 year low flow of 80 cfs. The capacity criteria for the
West Boise plant are also dependent on a certain amount of
Boise flow going to Lander Street. It would not be wise
to proceed to detailed plant planning for Lander Street,
and perhaps West Boise, until the flow issue is resolved.
Therefore, as a mitigation measure against possible adverse
effects, it is recommended that the facilities planners and
EPA not proceed to detailed planning for Lander Street or
West Boise until the flow issue is resolved, ..
Construction impacts should be minimized by using earth-
moving practices which minimize land disturbance and movement
of sediment toward watercourses. The Boise facility planners
have already met with Idaho Department of Fish and Game re-
garding minimization of construction impacts (CH2M Hill 1980c).
169
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Summary of Impacts
Urban growth due to expansion of sewage service will
contribute to increased runoff rates and higher storm peaks
in storm channels in the Boise area.
Pollutant loading to the river from the Lander Street
plant will not change. Violations of standards will be less
frequent due to dechlorination.
The increase in total pollutant load following expansion
of Boise facilities will be approximately 310 percent. This
may cause greater dissolved oxygen sags and algal growth
levels in the Boise River and in downstream Snake River re-
servoirs .
The l-in-10 year design flows for the Lander Street
plant are not assured. Detailed planning for these facilities
should not commence until the availability of the flows is
assured.
170
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Chapter 10
Fishery Resources
-------
Chapter 10
FISHERY RESOURCES
Existing Habitat Conditions and
Species Productivity
Aquatic habitats in Ada County include Lucky Peak,
Indian Creek, Blacks Creek, and Hubbard Reservoirs; numerous
irrigation canals and drains; the Boise River; the Snake
River; and numerous smaller streams, most of which flow only
seasonally (Figure 10-1). The Boise River is probably the
most significant aquatic habitat with regard to the potential
for impacts of Ada County wastewater management alternatives.
Boise River
^Historical Perspective. In the early 1800s, the Boise
River supported populations of white sturgeon, chinook salmon,
sockeye salmon, and steelhead rainbow trout (Caldwell and
Wells 1974). These fish are "anadromous" (i.e., they spawn
in fresh water and live a part of their life cycle in the
ocean). These fish populations migrated to and from the
Pacific Ocean via the Snake and Columbia Rivers. Salmon
were an important staple for the aboriginal Indian inhabi-
tants of the Boise River Valley.
Gold was discovered in the Boise River Basin in 1862,
and sedimentation due to placer mining activities soon severely
reduced salmon populations. The construction of Ba-rber Dam
in 1906, New York Diversion Dam in 1908, and Arrowrock Dam
in 1915 cut off the upper drainage areas to anadromous fish
migration (Ada Council of Governments 1973a). Subsequent
construction of impassable dams downstream on the Snake River
cut off the entire Boise River from anadromous fish migrations.
Present Day Fishes. Today the Boise River supports
a diverse fauna of native and introduced game and nongame
fishes (Table 10-1). Idaho Department of Fish and Game (IDFG)
data indicate that nongame fishes .outnumber game fishes by
about 10 to 1 (Figure 10-2). The nongame-to-game fish biomass
ratio is probably considerably larger than 10 to 1 due to
the large size of the suckers. The more abundant nongame
fishes are suckers, redside shiner, carp, and chiselmouth;
the more abundant game fishes are mountain whitefish, large-
mouth bass, and bluegill.
171
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Surface Waters
ADA COUNTY
X-*- PERENNIAL STREAM
..— INTERMITTENT ST.1EAX
& LAKES & RESERVOIR
Figure 10-1
172
SOURCE*: Ada Council of Governments 1973a.
-------
Table 10-1. Fishes of the Boise River Between
Lucky Peak Dam and the River Mouth
Common Name
Scientific Name
Coho salmon
Kokanee
Cutthroat trout
Rainbow trout
Brown trout
Dolly Varden
Mountain whitefish
Chiselmouth
Carp
Tui chub
Northern squawfish
Longnose dace
Speckled dace
Redside shiner
Bridgelip sucker
Largescale sucker
Mountain sucker
White catfish
Brown bullhead
Channel catfish
Tadpole madtom
Pumpkinseed
Warmouth
Bluegill
Smallmouth bass
Largemouth bass
Black crappie
Yellow perch
Mottled sculpin
Oncorhynchus kisutch
0. nerka
Salmo clarki
S^ gairdneri
S_. trutta
Salvelinus malma
Prosopium williamsoni
Acrocheilus alutaceus
Cyprinus carpio
Gila bicolor
Ptychocheilus oregonensis
Rhinichthys cataractae
R. osculus
Richardsonius balteatus
Catostomus columbianus
C. macrocheilus
C_. platyrhynchus
Ictalurus catus
_!. nebulosus
_!. punctatus
Noturus gyrinus
Lepomis gibbosus
L. gulosus
L. macrochirus
Micropterus dolomieui
M. salmoides
Pomoxis nigromaculatus
Perca flavescens
Cottus bairdi
SOURCE: Ada Council of Governments 1973a; Gibson 1978.
173
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TOTAL FISH
N=6041
GAME FISH
N = 516
NONGAME FISH
N= 5525
SOURCE^ GIBSON, 1978
WHITE CATFISH
YELLOW PERCH
BROWN TROUT
RAINBOW TROUT (HATCHERY)
RAINBOW TROUT (WILD)
BROWN BULLHEAD
BLACK CRAPPIE
CHANNEL CATFISH
PUMPKINSEED
SMALLMOUTH BASS
.2%
.2%
.6%
1.0%
1-2%
1.6%
2.3%
3.1%
4.0%
4.2%
TUI CHUB .1%
DACE 1.2%
SCULPIN 1.4%
SQUAWFISH 3.6%
FIGURE 10-2. PERCENTAGE COMPOSITION FOR TOTAL FISH, GAME FISH AND NON-
GAME FISH IN ELECTROFISHING SAMPLE FROM THE BOISE RIVER (FROM THE MOUTH,
UPSTREAM TO BARBER DAM), 11 JULY TO 2 AUGUST, 1974
-------
Distribution of Fishes. The species composition of
fishes in the river changes as one proceeds downstream from
Barber Dam to the river mouth (Figure 10-3). Coldwater
species are generally limited to the river reach above Star,
and warmwater species to the reach below Star. Although
whitefish are found in the entire river, they are much more
abundant above Star. Species composition in the vicinity
of Boise State University is dominated by whitefish and trout
(Kelley pers. comm.). Largemouth bass, black crappie, and
bluegill are found mainly in backwater sloughs below Star.
Smallmouth bass and channel catfish are most abundant in
the river from Notus to the mouth. Redside shiner, suckers,
carp, chiselmouth, and squawfish are more evenly distributed
than other species (Gibson 1978).
Rainbow trout are probably the most sought after game
fish in the Boise River. Population levels are maintained
by natural reproduction and by stocking with hatchery fish.
IDFG annually stocks about 30,000 catchable size fish at
various locations between Barber Dam and Star. Rainbow trout
comprise about 0.3 percent by number of all fishes in the
river according to electroshocking data (Gibson 1978). The
distribution of rainbow trout in the lower Boise River pre-
sently extends from approximately Star to Lucky Peak Reservoir.
Rainbow trout require good water quality and temperature
below about 70°F (21°C). For spawning, gravel should be
about 0.5-1 inch in diameter and be relatively free of fine
sediments (sand and silt).
Brown trout are a popular non-native game fish species
found in the Boise River. Population levels are maintained
by natural reproduction and stocking of hatchery-bred fish.
The IDFG annually stocks about 25,000 fingerlings in fall
in various locations between Barber Dam and Star. Brown
trout comprise about 0.01 percent by number of the fishes
in the Boise River, according to year-round electroshocking
data of Gibson (1978).
Both brown and rainbow trout are opportunistic carnivores,
feeding on a variety of invertebrates and smaller fishes.
Mountain whitefish are the most abundant game fish species
in the Boise River. The population is maintained entirely
by natural reproduction. Whitefish comprise about 4 percent,
by number, of the fishes in the Boise River (Gibson 1978).
In the Boise River, mountain whitefish spawn in early November
through mid-December, and egg incubation extends through
March (Reid pers. comm.). Mountain whitefish spawn in gravelly
areas; there is no evidence that they excavate any nest and
there is little or no selection of gravel size (Brown 1952).
Gibson (1978) investigated the food habits of mountain white-
fish in the Boise River. Immature aquatic insects were the
dominant food items.
175
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MOUNTAIN WHITEFISH
RAINBOW TROUT (HATCHERY]
RAINBOW TROUT (WILD)
LAR6EMOUTH BASS
BLACK CRAPPIE
BROWN TROUT
BLUE6ILL
SMALLMOUTH BASS
CHANNEL CATFISH
REDSIDE SHINER
SUCKER
CARP
CHISELMOUTH
SQUAWFISH
Barber Dam
\-/^
Fair view Strawberry
, Bridge , Glenn .Eagle
-^/-^^^^
Star
- BOISE RIVER
Coldwell Notus
i ' i
10 Miles , '""""
Mouth at
Parma Snake R.
SOURCE'- GIBSON, 1978
J
FIGURE 10-3. DISTRIBUTION OF 13 FISH SPECIES IN THE BOISE RIVER FROM BARBER
DAM DOWNSTREAM TO THE MOUTH AS DETERMINED BY ELECTROFISHING DURING
JANUARY-FEBRUARY, JULY-AUGUST AND OCTOBER, 1974
-------
Human Factors Affecting Aquatic Life. There are many
factors associated with human uses of the Boise River and
its watershed lands that affect the distribution and abundance
of fishes and other aquatic organisms in the river. Many
of these factors may also be affected directly or indirectly
by Ada County wastewater treatment alternatives. The following
discussions summarize the effects of these factors.
Hydrology. The annual stream flow regime of the Boise
River has been greatly altered by dam operations and diver-
sions for agriculture and as a result the Boise River below
Lucky Peak Dam has: 1) lower winter base flows; 2) reduced
winter and spring flood peaks; 3) summer flows that are higher
than natural near the upper and lower parts of the river,
but lower in the middle near Star; and 4) drastic short-
term flow fluctuations. Urbanization, overgrazing, and off-
road vehicle use have probably increased flood peak flows
in undammed smaller tributary streams such as Cottonwood
Creek and Five Mile Creek.
These hydrologic changes have multiple effects on the
fish populations. Lower winter flows cause lower pollutant
dispersion. They also promote formation of ice cover which
hinders oxygen transfer and which, in turn, may increase
the effects of waste discharges and occasional pollutant
spills during winter. Periodic fish kills in the river were
more common in the past. Many industrial waste discharges
have been eliminated or treated in recent years (Ada Council
of Governments 1973a). Short-term flow fluctuations or complete
flow shut-off for maintenance of the outlet structure of
Lucky Peak Reservoir strands fish and aquatic invertebrates
in pools and makes them more vulnerable to pollution. The
stranding of fish should be alleviated when the proposed
hydropower facilities are installed in Lucky Peak Dam. Higher
peak flood flows from small, undammed tributaries transport
high sediment loads from disturbed watershed areas.
These adverse effects can be mitigated in part by revising
the flow regime through Lucky Peak Dam. The recommended
minimum flow regime published by the U. S. Fish and Wildlife
Service Cooperative Instream Flow Service Group for maintenance
of fishery resources is presented in Table 10-2. Comparison
of actual flow frequencies to the recommended flow (Figure 10-4)
indicates spawning flows for rainbow trout are generally
met, but spawning flows for brown trout are not met.
On June 10, 1980, the Federal Energy Regulatory Commission
(FERC) issued a license to the Boise Project Board of Control
for new hydropower facilities on Lucky Peak Dam. A con-
tinuous minimum flow release of 160 cfs was a condition
177
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Table 10-2. Recommended Low Flow Regime in cfs, for the
Boise River from Lucky Peak Dam to Snake River
Spedes/L1fe Stage
Rainbow Trout
Spawning
Incubation
Brown Trout
Spawning
Incubation
Dolly Varden
Spawning
Incubation
Rearing All Species
Recommended Flow Regime
JAN
151
100
150
150
FEB
151
100
150
150
MAR
150
150
APR
225
151
150
225
MAY
225
151
150
225
JUN
225
151
150
225
JUL
151
150
150
AUG
151
150
150
SEP
150
150
OCT
225
151
150
100
150
225
NOV
225
151
150
100
150
225
DEC
151
100
150
150
SOURCE: Pruitt and Nadeau 1978.
178
-------
RAINBOW TROUT
SPAWNING
INCUBATION
REARING
BROWN TROUT
SPAWNING
INCUBATION
REARING
MTN. WHITEFISH
SPAWNING
INCUBATION
REARING
JAN
FEB
////7/j
MAR
APR MAY
MONTHS
JUN
JUL
AUG
SEP
OCT
NOV
DEC
10,000
en
u
O>
1,000-
o
m
100-
-------
of the permit. This would have enhanced fishery habitat
in the river. However, on October 9, 1980, FERC issued an
order repealing the minimum flow release condition. The
repeal was based on difficulties with the integrated manage-
ment of Lucky Peak, Arrowrock, and Anderson Ranch Reservoirs.
Sediment. Human alterations have changed the sediment
budget of the Boise River, resulting in:
o Arrowrock, Lucky Peak, Diversion, and Barber Dams
have blocked gravel recruitment from upstream areas.
This is "armoring" downstream areas, resulting in
sediment particle sizes too large for trout spawning
use (Nadeau pers. comm.). Most suitable spawning
gravels (about 0.5 inch diameter) exist in higher
side channel areas, and flows greater than about
1,000 cfs are necessary to provide suitable water
depths and velocities over them. Rainbow trout
spawn in these gravels during high flow periods of
spring, but the nests become exposed due to rapidly
falling water levels during summer, and the eggs
die (Pruitt and Nadeau 1978). Limited amounts of
proper-size spawning gravels are transported to
the main stem of Boise River by tributaries down-
stream of Boise area, such as Indian Creek (Nadeau
pers. comm.).
o The reach between Lucky Peak Dam and Barber Dam
has received extensive sand deposits from mining
operations in the More's Creek watershed in the
1930s and 1940s. These deposits stifle aquatic
insect productivity and are unsuitable for trout
spawning (Ada Council of Governments, 1973a).
o Fine sediments from sites of overgrazing and con-
struction activities, stream channel alterations,
and irrigation return flows are deposited in the
river. Urban development in the Boise foothills
and gravel crushing operations are especially dele-
terious (Ada Council of Governments 1973b). Sedi-
mentation renders stream gravels unproductive of
aquatic insects and unsuitable for trout spawning
due to the clogging of gravel interstices and
blockage of water circulation and oxygen transfer.
These changes in sediment budget may affect fish species
composition. The Boise River fish sampling data of Gibson
(1978) showed that game fish were 9.5 percent of the total
fish population, and of the game fish, 46 percent were mountain
whitefish, 2.2 percent were rainbow trout, and 0.6 percent were
brown trout. Mountain whitefish are closely related to rainbow
and brown trout; all three species are in the family Salmonidae.
180
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Both trout and whitefish are characteristic of cool, rela-
tively pollution-free streams, and feed mainly on terrestrial
and aquatic invertebrates. Although there is little infor-
mation on species specific habitat requirements and relative
resistance to various kinds of pollution for whitefish and
trout, they all are presumably about the same in habitat
requirements and resistance to various types of pollutants.
The great difference in relative abundance between trout
and whitefish in the Boise River can be explained by a single
significant difference between their life histories: trout
bury their eggs, while whitefish (and all other fish species
in the Boise River) do not. Mountain whitefish are fecund;
(i.e., prolific) lay their eggs over bottom types ranging
from fine gravel to coarse rubble, and do not build a nest
(Brown 1952). Rainbow and brown trout, on the other hand,
are not as fecund and require gravel of a definite size range
(about 0.5-1 inch) which is relatively free of fine sediments.
Sediments hinder water circulation to the buried eggs. Sedi-
ment characteristics thus appear to be a factor limiting
reproduction of rainbow and brown trout in the Boise River.
There is little gravel of the proper size above Boise, and
the suitable gravels below Boise are rendered unusable by
sedimentation. Other limiting or regulating factors (e.g.,
lower winter flows and high pollutant loads) during other
fish life stages probably affect trout and whitefish more
equally.
Sewage Treatment Plants. The present day effects of
treated sewage effluent discharges on fish populations in
the Boise River are difficult to assess. Studies have not
been undertaken since recent improvements were made in treat-
ment processes. The effects of water diversion and nonpoint
source pollution complicate assessment of the effects of the
discharges. Prior to the treatment plant improvements during
the winter low flow periods of 1957 and 1958, testing demon-
strated lethal effects on rainbow trout for a distance of
1 mile downstream from the Lander Street discharge point (Webb
1958) at river flows (Boise gage) of 16-95 cfs. There have
been no recent direct assessments of lethal or sublethal
effects on fish. Presumably, conditions have improved due
to the better treatment processes.
Below the Lander Street plant, water quality conditions
for ammonia, chemical oxygen demand (COD), dissolved oxygen (DO),
and coliform bacteria have periodically violated state stan-
dards for levels considered necessary for maintenance of
aquatic life.
In 1972-1973, prior to the upgrading of the Lander Street
plant, the Ada Council of governments (1975) conducted a
study which demonstrated the effects of treated sewage dis-
charges on the benthic macroinvertebrate community in the
Boise River. These results can be used to assess the effects
181
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of discharges on fish populations, since macroinvertebrate
populations are good indicators of water quality conditions.
The study showed that pollution-tolerant macroinvertebrates
were most abundant between Boise and Eagle Bridge (directly
downstream from the Lander plant). Above and below this
reach, pollution-sensitive invertebrates were greater. Up-
grading of the Lander Street plant since the study was con-
ducted may make the results obsolete; however, nonpoint source
pollution (sediment, oil and grease, rubber particles) may
have been partially responsible for the results observed.
Impacts of Flow Augmentation and Discharge Routing Alter-
natives
The Flow Augmentation and Flow Routing Technical Memo-
randum (CH2M Hill 1980b) presented five alternatives for the
Lander Street plant to meet former (1979) ammonia standards
(0-02 mg/1 at temperatures above 5°C, and 0.01 mg/1 at tempera-
tures below 5°C). The alternatives were:
1J River flow augmentation through use of uncontracted
Lucky Peak Reservoir storage capacity.
2) River flow augmentation through groundwater pumping.
3) River flow augmentation through water exchange
(groundwater or Snake River water exchange).
4) Temporary wastewater effluent storage.
5) Wastewater effluent discharge to Farmer's Union
Canal.
Since then the instream criterion for un-ionized ammonia
below the Lander Street plant was changed to 0.02 mg/1 year-
round. The facilities planners have performed additional
discharge modeling that indicates that they can meet the
new water quality standards without any river flow augmen-
tation, special discharge storage or routing schemes, or
special ammonia removal facilities assuming a l-in-10 year
low flow of 80 cfs (CH2M Hill 1980c). These alternatives
are no longer being considered because stream flow augmen-
tation or special sewage flow routing schemes are no longer
necessary to meet 1980 standards. Some of the alternatives,
however, are of interest due to their potential for beneficial
or adverse impacts on Boise River fishery resources. Main-
tenance of fishery resources may be a key factor in assuring
flow releases from Lucky Peak. These aspects are discussed
below.
182
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Direction Augmentation Through Use of Uncontracted Re-
servoir Storage Capacity- This alternative originally con-
sisted of four alternative hypothetical modes of Boise River
reservoir operation (Table 10-3). These modes ranged from
a 90th percentile low flow of 8 cfs (mode 1), to a mode which
gives a 90th percentile low flow of 130 cfs (mode 2) (Table 10-4]
The present mode (mode 3) gives a 90th percentile low flow
of 80 cfs.
Mode 1 would probably result in adverse effects on
fishery resources, particularly brown trout spawning. Winter
flow releases would be a constant 110 cfs. Pruitt and Nadeau
(1978) recommended stream resource maintenance flow of 225 cfs
(see Table 10-2). One hundred and ten cfs would provide
about 70 percent of the weighted spawning width for brown
trout (i.e., 70 percent of the total spawning habitat avail-
able at 225 cfs). Furthermore, this flow would be available
only 68 percent of all years.
Mode 2 would provide the greatest opportunity for
improving fish habitat conditions in .the Boise River, es-
pecially brown trout spawning. Under this mode, the stream
resource maintenance flows (225 cfs, October-November; 150
cfs, December-March) would be available 86 percent of all
years.
Mode 3, which approximates present reservoir operating
conditions, would provide the stream resources maintenance
flows 84 percent of all years.
Mode 4 would result in river conditions intermediate
between modes 1 and 3.
These direct augmentation alternatives are not strictly
alternatives in the sense that they can be directly imple-
mented by the project engineers or the City of Boise. The
reservoirs on the Boise River are operated by the U. S. Army
Corps of Engineers and the U. S. Water and Power Resources
Service. Both of these agencies are currently conducting
operational studies of Boise River reservoirs. The actual
amount of winter flow releases available for treated sewage
effluent dilution and for fishery habitat improvement will
probably depend on the findings of these studies.
Direction Augmentation Through Groundwater Pumping.
This alternative considered using idle well capacity during
winter to augment Boise River flows in years when the full
supply cannot be met. Full supply is not met about 16 percent
of all years under the present operating regime. This alter-
native would be beneficial to the Boise River fishery because
stream resource maintenance flows would be met in virtually
183
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Table 10-3. River Operation Mode Descriptions
Mode Operation Description
"Lucky Peak Reservoir fill accounting done with
irrigation, Fish and Game, and uncontracted space
all having same priority date. The entire uncon-
tracted space utilized for flood control or other
use so no non-irrigation season flow is available
from it. Water in the Fish and Game space is
released for non-irrigation season stream flow,
providing a continuous flow at Lucky Peak in years
with a full water supply. In years with only
partial supply available, the available supply is
released uniformly through the non-irrigation
season."
"Lucky Peak Reservoir fill accounting done with
irrigation, Fish and Game, and uncontracted space
all having some priority date. Water in the
entire uncontracted and Fish and Game spaces is
released for non-irrigation season stream flow to
provide a flow at Lucky Peak of 225 cfs in October
and November, and 150 cfs December to March if a
full water supply is available. If only a partial
supply is available, the available supply is
released uniformly through the non-irrigation
season."
"Lucky Peak Reservoir fill accounting done with
irrigation and Fish and Game space having priority
date senior to that for the uncontracted space.
(Uncontracted space filled last.) The entire
uncontracted and Fish and Game spaces are operated
as a unit identical to Mode 2. This approximates
the operation in the last 2 years. "
"Lucky Peak Reservoir fill accounting done with
irrigation and Fish and Game space having priority
date senior to that for the uncontracted space.
CUncontracted space filled last.) This mode
assumes that only one-half of the uncontracted
space is available for non-irrigation season flow
release. That one-half space and the Fish and
Game space is operated as a unit identical to
Mode 2. The other half of the uncontracted space
would be reserved for flood control and normally
net filled or the space would be otherwise commit-
ted and would not be available for stream main-
tenance flows. "
SOURCE: CH2M Hill 1980b.
184
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Table 10-4. Available Flows for River Operation Modes
(Based on an approximate simulation of river operation during 1928-1977 period)
Operation
Mode
Non-irrigation Season
Release From Lucky Peak
if Full Water Supply
Available
cf s
Time the Full Water
Supply Available
Years %
Release Possible
9 Years out of 10
With Available
Supplies
cf s
110
34
68
oo
t_n
225 Oct. & Nov.
150 Dec. thru Mar.
43
86
130
225 Oct. & NOV.
150 Dec. thru Mar.
42
84
80
225 Oct. & Nov.
150 Dec. thru Mar.
37
74
60
SOURCE: CH2M Hill 1980b.
1. See Table 10-3.
-------
all years, rather than in 84 percent of all years. Dis-
advantages of this alternative, as compared to alternatives
where flow augmentation would come directly from Lucky Peak
Reservoir, include: 1) there would be no instream flow benefits
to fish upstream of the point (s) where the well water entered
the river, and 2) increased energy consumption would be re-
quired for pumping the needed water.
Augmentation With Water Exchange. This alternative
considered two water exchange schemes to increase winter
stream flows.
Groundwate-f Exchange. This subalternative considered
pumping well water to irrigators during the summer in ex-
change for irrigation water stored in Lucky Peak Reservoir.
Stored waters would be released during the winter to meet
stream resource maintenance flows. This subalternative would
provide stream resource maintenance flows in all years, and
would provide more consistent year-to-year fish habitat flows
than the present chosen alternative. Energy would be required
for pumping.
Snake River Water Exchange. This subalternative con-
sidered pumping Snake River water to lands presently irrigated
with Boise River water in exchange for stored Lucky Peak
water to be released down the river during winter. Like
the groundwater exchange alternative, this subalternative would
be advantageous to the Boise River fishery because stream
resource maintenance flows would be provided in all years.
Increased energy consumption, however, would result from
pumping.
Temporary Storage. To meet ammonia standards, this alter-
native considered storing treated sewage flows that were
in excess of river assimilation capacity. Effluent would
be stored in a detention reservoir constructed near the Lander
Street plant and later discharged to Boise River during spring
and summer high flows. Under present reservoir operation
conditions, up to 4.1 MGD (6.4 cfs) would be stored at a
river flow of 80 cfs from Lucky Peak (105 cfs in Boise).
This flow removal would probably be insignificant in terms
of stream flow for physical fish habitat.
Canal Discharge. This alternative considered discharging
treated sewage flows in excess of river assimilation capacity
(up to 6.4 cfs) into Farmers Union Canal. The impact on
instream flows for the Boise River fishery would probably
be insignificant.
186
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Direct Impacts On Fisheries
Expansion of the Boise and Eagle wastewater treatment
facilities is not expected to have any significant adverse
effects on the fish populations of the Boise River as long
as the water quality standards are met. The facilities plan
(CH2M Hill 1980c) indicates that receiving water quality
standards can be met as long as flow releases from Lucky
Peak Dam equal or exceed 80 cfs, which is the anticipated
l-in-10 year low flow- However, additional assurance is
needed that 80 cfs will continue to be available during the
20-year life of the project, since part of that supply has
already been appropriated to the U. S. Water and Power Re-
sources Service and is subject to sale to irrigators. If
the l-in-10 year flow of 80 cfs is assured, then no signi-
ficant effects on fish populations will occur in 90 percent
of all years. In the other 10 percent of all years (the
lowest 10 percent in terms of water flow) some adverse fisheries
impacts may occur, depending on how far below 80 cfs releases
from Lucky Peak go. The potential for adverse effects on
fishes due to residual chlorine will decrease due to de-
chlorination facilities at the Boise wastewater treatment
plants.
•*#
Indirect Impacts on Fisheries
Indirect growth-related impacts on fish and wildlife
resources will result from the population growth and atten-
dant land use changes associated with provision of new or
expanded sewerage facilities. The present (1980) population
of Ada County is about 165,000-166,000. That population
is projected to increase to about 289,000 by the year 2000
(APA 1978). Of the total increase of 124,000 in Ada County,
about 75-85 percent (depending on the population estimates
used) is slated to occur in the three sewerage planning areas.
Provision of sewerage facilities appears to be a major factor
in guiding population growth in Ada County in the next 20
years.
The principal secondary impacts on fisheries accompanying
provision of sewerage facilities in Ada County will be nonpoint
source pollution resulting from population growth and urban
expansion. Nonpoint source pollution includes sediment, oil
and grease, rubber particles, and a host of other toxic or
oxygen-demanding substances (substances that consume oxygen
when decomposing, and thus may deplete the water of oxygen ne-
cessary for aquatic life). Increased fishing pressure may
also affect populations.
187
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Sedimentation is a major water quality problem in the
Boise River, especially below Boise. Fine sediments that
clog spawning gravels limit the natural reproduction of rain-
bow and brown trout in the river reach below Boise. New
construction from population growth and from interceptor con-
struction may worsen the problem. Insufficient data exist at
this time to quantify the present nonpoint source problem or
to quantify future loads and their effects. Additional dis-
cussion of sedimentation effects may be found under construction
impacts in Chapter 15.
Summary of Impacts
1. Significant direct effects on Boise River fish
populations are not expected to the extent that
water quality criteria in the Boise River are met.
The l-in-10 year low flow used in designing faci-
lities expansions needs to be assured in order
that the receiving water quality criteria can be
met.
2. The potential for adverse effects on fish due to
residual chlorine will be decreased due to addition
of dechlorination facilities at the Lander Street
plant.
3. Indirect impacts due to population growth will
consist of increased sediment load, and higher
flood peak flows from urbanized tributaries. In-
creased sedimentation of stream gravels will
lower habitat quality conditions for trout and
whitefish in the Boise River.
188
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Chapter 11
Vegetation and Wildlife Resources
-------
Chapter 11
VEGETATION AND WILDLIFE RESOURCES
Environmental Setting
In the following section describing the plant and animal
communities of the study area, special attention is given
to: 1) habitats of major importance to wildlife, 2) habitats
and wildlife that may be impacted by the proposed projects,
and 3) plant and animal species of special concern (e.g.,
endangered species, recreation species). Representative
plant and animal species of Ada-County are listed by common
and scientific name in Appendix E.
Vegetation and Wildlife Habitats
Wildlife Habitat Types. Nine general plant community
or wildlife habitat types occur in northern Ada County:
1) riparian, 2) big sagebrush, 3) bitterbrush shrub steppe,
4) irrigated agricultural, 5) nonirrigated agriculture,
6) open water, 7) grassland, 8) Douglas-fir, and 9) urban-
industrial (Idaho Department of Fish and Game 1977).
Riparian. Riparian habitat is densely wooded, typically
supporting cottonwoods, willows, wild roses, bulrushes, horse-
tails, cattails, and a variety of forbs and grasses. Rip-
arian areas provide excellent wildlife habitat with their
mix of water, wildlife forage plants, and cover. Riparian
habitat occurs along the Boise River, except where the river
-flows through the densely developed areas of the City of
Boise. One stretch of riparian habitat extends from Barber
Flats downstream through the Barber Pool area to the southern
end of the Warm Springs Golf Course. The Barber Pool area
supports approximately 650 acres of riparian habitat. Immedi-
ately downstream of the Strawberry Glen Airport in Garden
City lies approximately 225 acres of riparian habitat. A
150-acre stand of riparian habitat occurs on the north channel
of the Boise River southwest of Eagle. Except for these
three areas, the riparian community is seldom very wide
(>25 yards); in many cases the riparian vegetation is absent
or only a few trees wide. Riparian vegetation formerly extended
further inland from the active river channel, but has been
replaced by agricultural or urban-industrial uses. Downstream
of the Eagle area, the strip of riparian vegetation is usually
wider than that along the river near Boise. Riparian habitat
also occurs along some of the tributary creeks draining the
Boise Front.
189
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Sagebrush,, Bitter-brush, and Grasslands. Prior to urban!
zation and agricultural development in Ada County, most of
the county was brushland or grassland. Riparian habitat
occurred along the rivers, and forests were found in the high
mountains.
Bitterbrush-dominated shrubland presently occurs at
midelevations of the foothills north and east of Boise. Sage-
brush-dominated shrubland occurs in the foothills above and
below the bitterbrush communities, as well as comprising
most of the vegetation of southern Ada County. Grasslands
occur north of the Boise River and southeast of Boise, and
in small, scattered locations elsewhere in the county- In
addition, various grasses form part of the understory for
the forests and shrublands. Cheatgrass, crested wheatgrass,
bluebunch wheatgrass, Idaho fescue, and Indian ricegrass
are among the county's common grasses.
Aariculture. Large tracts of irrigated farmland lie
west of Boise and Eagle. Other scattered irrigated and non-
irrigated agricultural lands lie in eastern Ada County and
in southwestern Ada County near the Snake River. In the
last 10 years, large parcels of agricultural land southwest
of Boise have been converted to housing and other urban uses.
Corn is the primary row crop in the county. Alfalfa,
grains, sugar beets, and mint are among the other crops.
Irrigation is accomplished through furrow and large moving
sprinkler systems. Livestock production and dairies are
additional agricultural activities.
Open Water. Open water habitats are the surface waters
of lakes, reservoirs, and streams. Riparian habitat often^
occurs around the edges of such areas. Lucky Peak Reservoir,
Lake Lowell, Indian Creek Reservoir, and the Boise River
are examples of open water habitat. Large sewage treatment
ponds also serve as open water wildife habitat.
Douglas-Fir. Along the upper crest of the Boise Front
in northeastern Ada County, Douglas-fir and ponderosa pine
are the dominant plants. The forest community formerly extended
farther downslope and into some lower drainages; fires and
timber harvest have limited the forest to the higher slopes
Urban-Industrial. Boise, Garden City, Eagle, Meridian,
Star, and Kuna, as well as development in unincorporated
areas, comprise the urban-industrial habitats of Ada County -
190
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Within the Boise River floodplain, many areas support rela-
tively large trees. Parks, golf courses, and various open
space areas provide a combination of natural and artificial
(e.g., landscaping) vegetation within the urban complex.
Threatened and Endangered Plant Species. Two plant
species are listed as candidates for threatened or endangered
status by the U. S. Fish and Wildlife Service (Table 11-1).
Mulford's milk vetch and Hannah aase's onion are currently under
going evaluation to identify locations of populations, number
of plants, degree of endangerment, and other parameters which
will help to determine the status of these plants. The U. S.
Fish and Wildlife Service (Merhoff pers. comm.) expects to
officially propose these species for threatened or endangered
listing in the near future.
Both plant species are closely associated with soils
of sedimentary origin; locally these soils are found in a
narrow band at the base of the foothills east of Boise (Steele
pers. comm., U. S. Soil Conservation Service 1979). Because
these plants are closely associated with a specific limited
soil type, it is unlikely that further surveys will discover
numerous additional populations or broaden their known dis-
tributions .
Mulford's milk vetch historically has been identified
on 10 sites; but, only two populations have been recently
verified (Kennison 1980). Threats to this species are con-
version of native habitat to agriculture, excessive grazing
pressure, and urban development.
Hannah aase's onion has 10-12 known populations. Its means
of reproduction is by bulb division. A sexual reproduction
(bulb division) in this species has promoted uniformity
among plants within individual populations and notable dif-
ferences among populations. Maintenance of different popu-
lations is crucial to maintenance of the genetic variation
of the species. The total range of this plant is approxi-
mately 5 miles by 20 miles. Threats to the continued exis-
tence of this species are urban development and gravel ex-
traction (Packard 1979).
Wildlife
A variety of wildlife species utilize the habitats of
Ada County, either seasonally or year-round. Many species
are migratory, occurring in the county primarily during one
season or passing through the county briefly in spring or
fall. Deer, for example, summer in the high mountains, and
winter at lower foothills (because snow excludes them from
191
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Table 11-1. Vegetation - Candidate Threatened or Endangered Plant Species1
Plant Name
(Scientific/Common)
Proposed
Status"
Known Locations
Plant Community
Elevation, Slope, Soils
Coimients
Astragalus mulfordiae
Multo rd' s mi ]kve tch
Allium aaseae
Hanna Aase's Onion
Foothills east of
Boise; Owyhee, Wash-
ington Counties in
Idaho; Malheur Coun-
ty, Oregon; 5 sites.
Known only from the
benches in the vici-
nity of Boise and
Emmatt; 10-12 sites.
Steppe, shrub-steppe
desert shrub, sage-
brush-grass. Plant
associates include
sagebrush, bitter-
brush, fescue, wheat-
grass .
Immediate habitat
bare, bordered by
bitterbrush and
buckwheat; surroun-
ding community is
sagebrush-grass.
2,000-3,000 feet;
level to moderate
slope; sandy soils,
particularly along
old river deposits.
2,850-4,400 feet;
slope usually steep,
most often on eroding
faces of river ter-
races; gravelly and sandy
soils, sedimentary
in origin.
Seldom abundant
where it occurs, and
sites usually very
small.
Plants usually
abundant on proper
habitat, but such
sites very restric-
ted. Narrow habi-
tat suitability in-
dicates most of
potential habitat
is probably occu-
pied; no potential
alternate range.
'See Table 10-3 for definition of threatened or endangered
2 A total of 23 and 45 plant species in Idaho have been previously proposed for endangered or threatened status, respectively, by the U. S. Fish and Wildlife
Service, Office of Endangered Species (Federal Register: June 16, 1976; July 1, 1975). The list of proposed species expired December 10, 1979. Species
that had not either been officially designated threatened/endangered or deleted from the proposed list remained candidate species. Status of candidate spe
cies are continuing to be reviewed; as a result some species have been officially reproposed (and officially listed in some cases) . The two candidate spe^
cies listed above are undergoing evaluation and will be officially proposed for threatened or endangered listing in the near future. Two other species in ^
eluded in the initial proposals (Draba douglasii and Primula cusickiana) have been recommended for deletion from further threatened or endangered considera
tion (Marhoff p^rs. comra.).
3Data Sources: Henderson et al. (1977); Packard (1979); Kennison (1980).
''Status listed in expired proposals (see note 2 above) . T = threatened; E = endangered.
5Henderson et al. (1977) recommended changing status to endangered.
-------
the higher elevations). Reptiles, on the other hand, are
year-round residents because of their restricted mobility.
Wildlife by Habitat Type. Some of the characteristic
or common wildlife species inhabiting each of the county's
habitats are discussed below. Some wildlife species are
closely associated with a given habitat, whereas other species
occupy several habitats.
Riparian. Riparian habitat generally supports a more
diverse wildlife population than any other habitat type
because of the diversity of food and cover plants and the
availability of water.
Muskrats and beavers have been reported in the Barber
Pool area. Raccoons, deer, skunks, and foxes typically inhabit
riparian areas.
The most visible component of the wildlife community
in riparian areas is the various water-associated birds.
Great blue herons, Canada geese, mallards, green-winged-teals,
belted kingfishers, and killdeer are common on the water
and in the adjacent vegetation. Yellow-headed blackbirds,
red-winged blackbirds, and quail may be observed in the ad-
joining upland areas. Black-billed magpies construct their
stick nests in the trees. Great blue herons have established
rookeries near Eagle (Figure 11-1) and Star (Ada Council
of Governments 1973a) . Birds of prey are commonly observed__
in or near riparian habitat. Bald eagles, ospreys, marsh
hawks, and Swainson's hawks have been seen along the Boise
River.
Amphibians, such as the spotted frog, are common in
riparian areas due to abundant water supplies. Garter snakes
and other reptiles may also be observed.
Sagebrush, Bitterbrush,, and Grasslands. The arid foot-
hill and southern portion of the county support sagebrush,
bitterbrush or grassland habitats. Coyotes commonly occur
in these habitats, preying largely upon mice and other small
mammals. Deer migrate from the higher mountains into these
areas during winter, feeding on the shrubs and other plants
remaining uncovered by snow. Badgers, Ord kangaroo rats,
Townsend ground squirrels, and black-tailed jackrabbits are
among the other common mammals of these habitats.
Brushlands and grasslands are foraging habitats for
many birds of prey, such as golden eagles, prairie falcons,
kestrels, burrowing owls, and ferruginous hawks. Other birds
characteristically inhabiting such areas are sage grouse,
long-billed curlews, ravens, horned larks, meadowlarks, and
savannah sparrows.
193
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TREATMENT PLANTS
0 I««LI
VI1T aoitt
© L««0i« IT
0 OOWAN FtfLD
A
I
FIGURE 11-1. SPECIES OF SPECIAL CONCERN HABITAT
FIGURE 11-2. DEER AND ELK HABITAT
194
-------
Western fence lizards, western rattlesnakes, and sage-
brush lizards are typical reptiles in this habitat. Amphi-
bians are uncommon because of arid conditions.
Agriculture. Farmland provides suitable habitat for
many wildlife species, as long as escape and breeding cover
is maintained between and around the fields. Ring-necked
pheasant, mourning doves, quail, and cottontail rabbits are
major species of agricultural areas. Waterfowl feed on stubble
and leftover grain in harvested fields. Marsh hawks, burrowing
owls, and coyotes will forage for the mice and other small
mammals that live on farmlands. Amphibians occur in the
irrigation and drainage ditches.
Open Water. Open water habitats serve as resting and
feeding areas for waterfowl and other water-associated birds.
Many species remain in the county year-round, breeding and
nesting in vegetation adjacent to the water. Barber Pool
is an excellent waterfowl breeding area, producing 125-150
Canada geese annually (Ada Council of Governments 1973a).
The greatest water-associated bird populations occur during
spring and fall migrations. Mallards, green-winged teal,
shoveler, California gulls, white pelicans, American avocets,
and great blue herons are some of the species using the lakes
and streams of Ada County. Osprey and bald eagles forage
for fish and bald eagles prey on waterfowl in this habitat.
Douglas-Fir. Mammals inhabiting the Douglas-fir areas
include elk, deer, snowshoe rabbits, red squirrels, golden-
mantled ground squirrels, porcupines, and bushytail woodrats.
Bird species include blue grouse, ruffed grouse, mountain
chickadees, pine siskins, and red-breasted nuthatches. Spotted
frogs and garter snakes also occur in this habitat.
Urban-Industrial. Wildlife species inhabiting urban
areas are tolerant of human activity- Three of the most
common species (i.e., house mouse, house sparrow, starling)
are introduced. Other species include raccoons, common night-
hawks, black-billed magpies, cedar waxwings, and robins.
Threatened Species, Endangered Species, and Species
of Special Concern. Four mammal, ten bird and two reptile
species designated as endangered or known to be of special
concern to governmental agencies or private groups are
occasional, seasonal, or year-round inhabitants of the study
area. Table 11-2 summarizes the status, habitat requirements,
food habits, distribution, and other information regarding
these species. Of the listed species, the bald eagle and
long-billed curlew are the most likely to be impacted by
the current project; these two species are discussed below.
195
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Table 11-2. Terrestrial Wildlife - Endangered and Threatened Species and Species of Special Concern1
Carmen Name
Status
Habitat and Special Requirements3
Food Habits3
Distribution/Garments3
Spotted bat
River otter
Kit fox
Bobcat
Ferruginous hawk
»-•
o\ Southern ba]d eagle
Osprey
Prairie falcon
Peregrine falcon
Columbian sharp-
tailed grouse
Bobwhite
MAMMALS
Sen, PT Usually arid open or scrub habitat; may
enter buildings and caves; highly selec-
tive of daily roost sites in cracks and
crevices of high cliffs and canyons.
Sen Riparian habitats along streams and lakes
Sen, Sp Con Vegetation arid land; open, level sandy
ground for burrowing.
Sen, Sp Con May occur in most wildlife habitats in
county; dens in rock crevices and
hollow logs.
BIBDS
Sen, Sp Con, Arid sagebrush lands; grasslands, range-
PT, BL lands, open country; nests built of
sticks (primarily big sagebrush) in
cliffs, in trees, or on the ground;
readily deserts nests if disturbed.
E, Sen Roost near rivers, reservoirs, and
lakes providing sufficient food supply;
also forages in adjacent sagebrush,
grassland, and agriculture; scavenger
and predator.
Sen, PT, BL Roost and forage near rivers, reser-
voirs and lakes.
Sp Con, PT, BL Tall sagebrush and shrublands in Ada
County; plains, prairies, deserts;
nests on cliffs.
E, Sp Con Wide ranging; open country; nests on
cliffs usually near marshes and streams
providing adequate food.
Sen, Sp Con, Nonirrigated agriculture, grass-shrub
PT, BL habitat, prairie.
Sp Con CottonwoccHrfillow riparian; farmland;
brush open country; roadsides.
Primarily moths
Fish
Small rodents
Small mammals,
birds, carrion
Jackrabbits,
cottontails,
and rodents
Fish, waterfowl,
rabbits, rodents
Fish
Ground squirrels,
other small
mammals, birds
Birds
Seeds, buds,
berries
Seeds of legumes,
weedy herbs, and
cultivated grains,
insects
Extremely uncommon; summer migrant.
Probably few (if any) in Boise River
below Lucky Peak Dam.
Very rare; confined to arid areas in
southern portions of the state.
Some populations have been considera-
bly reduced in recent years; probably
few (if any) in Boise River below
Lucky Peak Dam.
Restricted to the sagebrush areas of
the Snake River plains; populations
limited; observed occasionally.
Winter migrant; as many as 12 bald
eagles have been observed wintering
along lower Boise River; Barber Pool
primary wintering area.
Seasonal migrant in southern Idaho.
Snake River Birds of Prey Natural
Areas has one of the world's largest
nesting populations (i.e., 5 percent
of world's total).
Very uncommon seasonal migrant.
Low populations in Ada County.
Low, stable populations in restricted
habitat; along Boise River downstream
of Garden City.
-------
Table 11-2 Cont'd.
Common Name
Status2
Habitat and Special Requirements3
Food Habits3
Distr ibution/Conments
Mountain quail
Sen, Sp Con
Northern long-billed Sen, PT, BL
curlew
Western burrowing cwl Sen, PT, BL
Bitterbrush shrub steppe; brushy moun-
tain and, forest slopes.
Open short grass prairie; agriculture,
rangelands, sagebrush and bitterbrush
shrublands.
Grasslands, sagebrush, desert, farms;
utilizes former rodent and badger
burrows.
Pine seeds, acorns
berries
Insects
Small mammals,
insects
Low population north of Lucky Peak Res-
ervoir; and Along Crane, Hulls, Warm
Springs, and Maynard Creeks.
Nest north of Barber Pool.
Populations: lew in winter-spring;
medium in summer-fall.
Western ground snake Sen, Sp Con
Desert night snake
Sp Con
REPTTT.KS
Annual grasslands; tall sagebrush; sand
and subsurface moisture.
Annual grasslands; tall sagebrush;
deserts.
Spiders, centi-
pedes , insects,
insect larvae
Frogs, lizards
Medium year-round population levels.
Medium year-round population levels.
1Species of Special Concern: Species whose population numbers are known to be of concern to governmental agencies or scientific, educational, or public
interest groups.
2Status:
E - Endangered Species: designated endangered under the Federal Endangered Species Act of 1973 (as amended through December 28, 1979). "The term
'endangered species' means any species which is in danger of extinction throughout all or'a significant portion of its range other than a species
of the Class Insecta determined by the Secretary to constitute a pest whose protection under the provisions of this Act would present an over-
whelming and overriding risk to man."
T - Threatened Species: designated threatened under the Federal Endangered Species Act of 1973 (as amended through December 28, 1979). "The term
'threatened species' means any species which is likely to become an endangered species within the foreseeable future throughout all or a signifi-
cant portion of its range. '
Sen - Sensitive Species: Designated as sensitive in a Master Memorandum of Understanding between the Idaho Department of Fish and Game and the U. S.
Bureau of Land Management (1977). Sensitive species are those lacking official listing and: "... [a] whose populations are consistently small
and widely dispersed, or whose ranges are restricted to a few localities, such that any appreciable reduction in numbers, habitat availability, or
habitat condition might lead toward extinction; and [b] whose numbers are declining so rapidly that official listing may become necessary as a
conservation measure."
Sp Con - Species of Special Concern: Listed as a species of special concern in the fish and wildlife "Policy Plan" of the Idaho Department of Fish and Game
(1978). "Species of special concern are those species whose restricted range, specific habitat requirements and/or low population numbers make them
vulnerable to elimination from the state if adverse impacts on populations or habitat occur."
PT - Potentially Threatened: included in the original identification of potentially threatened wildlife, the "Red Book" (U. S. Fish and Wildlife Service
1973), but not now designated as endangered or threatened (U. S. Fish and Wildlife Service 1980); or listed as status-undetermined by Mohler (1974).
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Table 11-2 Cont'd.
BL - Blue List: Included in the National Audubon Society "Blue List"; an "annual 'early warning list' of declining, threatened, or vulnerable [bird]
species" (Arbib 1979). Only those species having sone additional status designation arc listed above.
3llabitat requirenents, life history, distribution, and other information taken from: Durt and Grossenheider 1976; Idaho Department of Fish and Gane 1977,
1978; Jensen 1980; Mohler 1974; National Fish and Wildlife Laboratory 1980; Peterson 1961; Snow 1972, 1973, 1974a, 1974b, 1974c; Stebbins 1966; U. S.
Bureau of Land Management 1980; U. S. Fish and Wildlife Service 1973; Zarri 1974a, 1974b.
vo
00
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Bald Eagle, The southern bald eagle is designated
"endangered" by the U. S. Fish and Wildlife Service. His-
torically and as late as the 1880s, bald eagles nested along
the Boise River near Eagle, feeding on the large steelhead
and salmon runs. Elimination of the fish runs by damming
the river and the urbanization of the Boise area has restricted
local bald eagle activity primarily to winter use of the
Barber Pool (Figure 11-1) (Keating pers. comm.). One to
five bald eagles make incidental use of the Boise River ri-
parian habitats between Boise and Star (Howard pers. comm.).
Barber Pool is a large area of wooded riparian habitat,
islands, and braided river channels behind Barber Dam. An
abundant whitefish and salmonid fishery provides the primary
prey for the eagles; waterfowl, jackrabbits, and various
upland species comprise a smaller percentage of the prey.
Jensen (1980) surveyed the Boise River between Mores Creek
Bridge and Boise during the winter of 1979-1980. As many
as 12 bald eagles were observed along the river, 7 in Barber
Pool. Bald eagles occupied the area from late October to
early April. Eagles roost in taller cottonwoods and on cliffs
south of the river.
Northern Long-billed Curlew. The northern long-billed
curlew is one of 14 bird species designated as "sensitive"
under a memorandum of understanding between the Idaho Depart-
ment of Fish and Game and the U. S. Bureau of Land Management
(1977). The species has no official threatened or endangered
status, but was listed by the U. S. Fish and Wildlife Service
(1973) as a "status undetermined" species (i.e., possibly
threatened with extinction, yet sufficient information to
conclusively determine its status was lacking). Mohler (1974)
also listed this species as status undetermined.
The long bill and long legs of the curlew adapt it to
feeding on insects in short grass plains, rangelands, and
agricultural fields. Nesting occurs in open prairie and
is easily disturbed by human activity.
Curlews are largely spring and summer inhabitants of
Ada County, usually leaving Idaho to migrate to the south-
western United States by August. Curlews nest in suitable
upland habitat northeast of Barber Dam (Keating pers. comm.),
and in central and northwestern Ada County (Ada Council of
Governments 1973a) (Figure 11-1). The U. S. Bureau of Land
Management recently conducted a study of long-billed curlews
in Canyon County; analysis and publication of results have
not been completed.
Recreational Species. A variety of recreational wildlife
(i.e., game species) occur in Ada County. Ducks, ring-necked
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pheasant, mourning doves, chukar partridge, quail, and Hun-
garian partridge are the major birds harvested in the county;
blue grouse, ruffed grouse, geese, and sage grouse are also
taken. Elk, deer, and cottontails are the county's game
mammals. Figures 11-2 through 11-6 illustrate the distri-
bution of some of these species in Ada County.
Deer migrate to the lower foothills of the Boise Front
or south of Lucky Peak Reservoir from higher elevations during
winter when snow is deep or temperatures are severe. Deer
formerly migrated onto the Snake River Plain as far downstream
as Lake Lowell; urbanization has eliminated most such long
migrations.
Breeding areas for waterfowl are limited in Ada County,
although approximately 10,000 ducks are produced annually
from breeding areas in Barber Pool, along the Boise River
downstream of Garden City, along the Snake River, and at
the county's smaller reservoirs.
Quail occur in the riparian and brushy habitats along
several of the county's creeks and the Boise River. Chukar
and Hungarian partridge inhabit arid brushlands and some
agricultural fields. Blue grouse and ruffed grouse are
restricted to the timbered areas of the Boise Front; sage
grouse occur in sagebrush habitat south of Lucky Peak Reservoir.
Pheasant occur in most of the agricultural areas of
the county. Pheasant are well adapted to farmland habitat,
as long as sufficient cover exists along fencerows, between
fields, and along roads. Consolidation of small farms into
large farms, cultivation and mowing up to and directly adjacent
to the fenceline, and modern sprinkler irrigation techniques
reduce availability of suitable habitat to pheasants.
Mourning doves are widespread throughout most of Ada
County. Farms, grassland, brushland, riparian areas, and
woods all provide habitat for this species.
Impact Analysis
The projected direct and indirect impacts of the planned
facilities are discussed below. Direct impacts are those
resulting from facility construction or operation at the
plant sites, along the pipeline routes, or at the sludge
disposal sites. Indirect impacts are those resulting from
growth and urbanization that would not have occurred without
increased waste treatment capacity.
200
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A
FIGURE 11-3. WATERFOWL HABITAT
FIGURE 11-4. QUAIL AND GROUSE HABITAT
201
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FIGURE 11-5. PARTRIDGE HABITAT
FIGURE 11-6. PHEASANT & DOVE HABITAT
202 ™—
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Direct Impacts
Lander Street and West Boise. Expansion of the capacity
of the Lander Street and West Boise facilities will have
few direct impacts at the plant sites. Biotic communities
of the sites are currently highly disturbed. Most construction
will occur within the existing plant sites in areas formerly
used for waste treatment or in landscaped areas. Disturbance
of local wildlife during construction should be minor and
temporary. Disturbance caused by operation of the expanded
plant should not be significant.
Construction of the sludge pipeline will impact plant
communities slightly along the route, including riparian habitat
where the pipeline crosses the river. The vegetation should
recover following construction if no right-of-way maintenance
program is instituted.
Sludge disposal at the penitentiary should have little
or no effect on wildlife. If additional acreage is brought
under cultivation as part of the project, some of the native
species supported on the presently uncultivated land will
be lost. The cultivated fields, however, will provide forage
for agriculture-tolerant species.
Eagle. Construction of the new Eagle facilities treatment
ponds will eliminate a minimum of 15 acres of riparian habitat
along the Boise River. Additional riparian acreage will be
eliminated by construction of facility buildings and roads,
as well as the connecting pipeline between the old and new
facilities.
The proposed plant site is located in a flood hazard zone
and is in one of the largest riparian communities along the
river. The riparian community provides excellent habitat
for deer, raccoons, yellow-headed blackbirds, kingfishers,
great blue herons, and many other species because of its
size and configuration (extends over 100 yards inland from
the edge of the river). Riparian areas that are only a line
of trees or a narrow band of vegetation along the streamcourse
do not support the great wildlife diversity that such a large,
deep parcel is able to support. The riparian habitat at
the Eagle site is of even greater importance because it is
one of only three large riparian areas in the reach of the
river from Boise to Eagle (the other two are: 1) downstream
of the Strawberry Glen Airport, and 2) at Barber Pool).
' Loss of the riparian habitat will reduce the wildlife
populations inhabiting the site. Water-associated birds
and mammals will be detrimentally affected. Available roosting
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sites for raptors, including possibly an occasional bald
eagle, will be reduced.
Executive Order 1190, Protection of Wetlands, will apply
to the proposed Eagle plant site. The order "requires Federal
agencies conducting certain activities to avoid, to the extent
possible, the adverse impacts associated with the destruction
or loss of wetlands and to avoid support of new construction
in wetlands if a practicable alternative exists" (40 CFR 6.302).
As defined in this policy, "wetlands" includes marshes, sloughs,
river overflows, and similar areas. EPA's Statement of Procedures
on Floodplain Management and Wetland Protection (44 FR 1455) re-
quires EPA programs to determine if proposed actions will affect
wetlands. If a program will affect a wetland, the responsible
official must prepare a wetlands assessment. Adverse impacts
to the wetlands must be avoided if possible or mitigated if no
practical alternative exists.
The pipeline from the ponds to the rapid infiltration site
is expected to run along existing rights-of-way. Such areas
are already highly disturbed, and construction impacts on wild-
life should be negligible.
The rapid infiltration site is currently under cultivation
and is immediately adjacent to a heavily stocked feedyard that
is completely lacking in vegetative cover. A wooded canal
that will carry infiltration effluent runs along the south side
of the site. No impacts are expected at the site with the
possible exception of some disturbance in the canal when
drainage pipes are being installed.
Southwest Area. Because the "rural lifestyle" land use
plan (APA 1980) for this area is currently the most likely to
be implemented, no direct impacts are foreseen.
Indirect Impacts
Boise and Eagle. The major impacts of expansion of the
Boise and Eagle facilities will result from accommodating
urban growth. The habitats primarily impacted will be the
agricultural lands and the arid brushland-grasslands in the
foothills of the Boise Front and on the Snake River.
Many or all of the local populations of the two candidate
threatened or endangered plant species could be lost to ur-
banization if no provisions are made for protecting the popu-
lation. Developments impacting these endangered plants may
be proposed and approved without the facilities expansion.
Loss of the farmlands, brushlands, and grasslands will
reduce the populations of the species (e.g., pheasants and
mourning doves) inhabiting those areas. Foraging habitat
for raptors such as kestrels and marsh hawks will be reduced.
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As urban areas extend into the foothills, deer winter
ranges will be detrimentally affected. Although most of the
crucial wintering areas of the Boise Front are in public
ownership (Parker pers. comm.), some important areas will
be lost, and the incremental losses of wintering areas of
lesser importance will continue. Increased recreation,
especially off-road vehicles and snowmobiles, will also
degrade the wildlife habitats along the Boise Front.
Urban growth will likely impact the feeding or nesting
areas of the long-billed curlew, through both direct habitat
loss and disturbance by increased human activity in adjacent
areas. Urbanization near Barber Pool will increase disturbance
and decrease secondary foraging habitat for bald eagles. Higher
local human populations will increase use of the Barber Pool
area for recreation. The majority of recreation use, however,
should occur in summer when eagles are absent. The level of
nearby human activity that bald eagles will tolerate is unknown.
Southwest Area. The loss of agricultural and brushland-
grassland habitat to high density urban development will be
avoided by implementing the "rural lifestyle" alternative.
Urban growth will occur on larger lots suitable for septic
tank systems, however, taking some farmland out of production,
replacing existing vegetation with landscaping plants, and
increasing human activity. Pheasants and other farmland
wildlife will be detrimentally impacted, and raptor foraging
habitat will be reduced. These impacts will be less severe
than would be projected for higher density development.
Impact Summary
Few direct wildlife impacts will result from the proposed
projects. A major direct detrimental impact will be the
loss of a large area of Boise River riparian habitat at the
proposed Eagle plant site. Accommodated urban growth will
cause the greatest long-term impacts on wildlife. Conversion
of open spaces in the foothills and on the plain to housing
and industry will reduce the available habitat for many species.
The bald eagle and long-billed curlew are especially vulnerable
to disturbance.
Potential Mitigation Measures
Prior to any decision to provide federal assistance to the
City of Eagle for wastewater treatment facilities, EPA will
evaluate alternative sites that may either avoid or lessen
the impact to the existing wetland. If, in its evaluation,
EPA finds that no other feasible alternatives exist, miti-
gation measures aimed at protecting the wetland will be pro-
posed and coordinated with the U. S. Fish and Wildlife Service.
The results of the evaluation will be included in the Final
EIS.
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Urbanization and recreation within or adjacent to Barber
Pool should be planned to minimize bald eagle disturbance.
Development, for example, should be discouraged near the cliffs
used as roosting sites, and winter recreation should be dir-
ected toward the periphery of the pool, rather than through
the middle of it. Similarly, development should be directed
away from curlew nesting areas.
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Chapter 12
Agricultural Lands in Ada County
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Chapter 12
AGRICULTURAL LANDS IN ADA COUNTY
Introduction
An important environmental issue is the impact on agri-
cultural lands of community growth accommodated by expanded
wastewater treatment facilities. The preservation of agri-
cultural lands in the face of development pressures is con-
sidered a significant land use issue in Ada County.
At the national level, EPA has established a policy
to protect agricultural lands by not undertaking any action
or program that would encourage the loss of important agri-
cultural lands. EPA's policy is a direct outgrowth of a
national policy to protect prime agricultural land.
This chapter describes agricultural resources in Ada
County, reviews policies on the protection of agricultural
resources, and assesses the agricultural conversion process
as it relates to Ada County.
Agricultural Resources in Ada County
Although Ada County has historically been viewed as
the center for business and government in Idaho, agriculture
has also played an important role in the local economy.
In 1974, the total market value of all agricultural products
sold surpassed $34 million. Principal farm products included
wheat, barley, alfalfa, corn, livestock, and livestock-related
products.
The identification of agricultural lands as prime farm-
land is based on soil characteristics, climate and water
availability. The presence of these conditions allows for
the production of "relatively more food with less erosion
and with lower demand for fertilizer, energy and other
resources" than nonprime land (Peterson 1976) .
In Ada County, prime farmland has not been mapped. Al-
though the Soil Conservation Survey has recently completed
a soil survey in Ada County, the designation of prime farm-
land was not provided. In the absence of Soil Conservation
Survey designation, prime farmland in Ada County can be
identified based on prior mapping of soil capability and
207
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water availability. All lands designated as Class I and
Class II in Figure 12-1 are considered prime farmland. The
soil classes are described in Table 12-1.
Trends in Agricultural Use
Information identifying present trends in agricultural
use for Ada County is limited. According to the 1974 Census
of Agriculture (U. S. Bureau of the Census 1977) there were
approximately 75,000 acres of irrigated cropland in Ada County
in 1974. Other estimates of irrigated cropland in Ada County
include 125,000 acres in 1975 by the Idaho Department of
Water Resources (1978) and approximately 112,000 acres in
about 1970 by ACOG (1975b). This wide range in estimates
of irrigated farmland makes it difficult to determine any
distinct trends in agriculture production in Ada County-
•
Some information on trends in agricultural use in Ada
County is presented in the 1974 Census of Agriculture for
Idaho (Table 12-2) . Although it appears that some clear-
cut trends such as decreasing farm size are evident, reports
from Ada County sources conflict with this conclusion (ACOG
1975b). Local officials are not in agreement as to the impact
of urbanization on irrigated cropland in Ada County (Johnson
pers. comm.).
Agricultural Lands Conversion Process
The continued loss of agricultural lands, and particularly
prime farmland, has become a national concern because prime
agricultural land is a nonrenewable resource and its conversion
to urban uses is irreversible. Pressures influencing the
conversion of farmland to urban development are complex and
have been addressed at all levels of government.
An Overview of Agricultural Land Conversion Process
A farmer's decision to sell farmland for development
is a complex phenomenon. According to the U. S. Council
on Environmental Quality (Peterson 1976) four different
types of factors appear to be at work: economic (market
forces), demographic (age), secondary (impacts on neighboring
land uses), and transitional (desire for change).
Economic Factors. Economic factors are of two kinds.
First, a very high price for a farm may be offered, in which
case it may be difficult not to sell the farm. Second, economic
returns may not be sufficient to continue farming. Causes
208
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— Nl-
-LEGEND=
| A. Moderately coarse to medium textured soils on steep
mountain slopes of the Idaho Balhalith.
A-f Tokeiichi -Olo Association
A-2 Rainey - Olo - Brovniee Assocration
I B. Moderately coarse to very fine textured soils on rolling
to very steep lacustrine & fluvitile deposits of the
Glenns Ferry Formation.
8-t Ado-Brent-Day A!lociolion
B-2 Lolal ita -Lankbush-Pcyette Association
B-3 Lonkbush-Lololita-Hoi Aiiocrohon
B-4 Lanktree - Ada - Dfly Association
| C. Medium to moderately coarse textured soils on alluvial
bottoms & lowlands on level to nearly level slopes
C-1 Hflrpl- Bissell - Jenness Association
C-2 Folk-Moulton-Goose Creek Association
C-3 Bram -Moulton- Baldock Association
C-4 Oliogo - Windock - Orax Association
0. Medium to very fine textured soils on nearly level or
level alluvial terraces above the Boise River.
D-f Purdom - Power - Tess Association
D-2 Elijah -Collnorp -McCain Association
0-3 Chllcott-Lank tree- McCain Association
Medium textured loess-like soils over Snake River
basalt or alluvial gravels on level to gently rolling slopes
E-1
E-Z
E-3
e-4
E-5
Potroti - Seism - Trev ino A
Garbutt - Bahem - Seism Asso
Seism - Boh em -Trevino Asso
Elijah -Cofthrop- Trevino A
Minidoka - Sc ism -Cencove As
sociotio
lotion
iation
sociotio
ociation
| F. Moderately coarse to medium textured soils on nearly level
to gently sloping terraces and alluvial fans adjacent la
the Snake River.
F-1 Turbyfill - Felthom- Cencove Association
| G. Very shallow to non-existent soil mantle on rock outcrops,
bluffs and cliffs along the Snake River Canyon.
6-1 Rock Outcrop • Canyons Associations
Indicates A Dry Classification
Indicotts An Irrigated Classification
FIGURE 12-1. SOILS CAPABILITY
FOR AGRICULTURE
.209.
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Table 12-1. Soils Capability for Agriculture
Agricultural land capability classification contains two
general divisions: 1) Land suited for cultivation and
other uses (Classes I through IV) , and 2) land limited
in use and generally not suited for cultivation (Classes V
through VII) The capability classification is a practical
grouping of soils. Soils and climate are considered to-
gether as they influence the use, management, and pro-
duction of agricultural endeavors.
The agriculture capability classes are of a general nature
with each class representing general uses applying in
each class. The classes are briefly described as follows:
Class I: Soils in Class I have few or no limitations or
hazards. They may be used safely for culti-
vated crops, pasture, range, woodland or
wildlife.
Class II: Soils in Class II have few limitations or ha-
zards. Simple conservation practices are
needed when cultivated. They are suited
for the same uses as Class I.
Class III: Soils in Class III have more limitations and
hazards than those in Class II. They re-
quire more difficult or complex conserva-
tion practices when cultivated . They are
suited for the same uses as Class 1.
Class IV: Soils in Class IV have greater limitations
and hazards than Class III. Still more diffi-
cult or complex measures are needed when
cultivated. They are suited for the same
uses as Class I.
Class V: Soils in Class V have little or no erosion
hazard but have other limitations that pre-
vent normal tillage for cultivated crops.
They are suited to pasture, range, woodland
or wildlife.
Class VI: Soils in Class VI have severe limitations or
hazards that make them generally unsuited
for cultivation. They are suited largely to
pasture, range, woodland or wildlife.
Class VII: Soils in Class VII have very severe limita-
tions or hazards that make them generally
unsuited for cultivation. They are suited
to grazing, woodland or wildlife.
Class VIII: Soils and land forms in Class VIII have limi-
tations and hazards that prevent their use
for cultivated crops, pasture, range or wood-
land. They may be used for recreation,
wildlife or water supply.
Capability classes are divided into subclasses. These
show the principal kinds of conservation problems invol-
ved. The subclasses are: "e'1 for erosion, "w" for wet-
ness, "s" for soil and "c" for climate. For example,
A-l (Takeuchi-Ola association) is Class VII e, i.e., a
Class VII soil with erosion limitation.
SOURCE: Ada Council of Governments (AGOG) 1975a.
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Table 12-2. Farms, Land in Farms, and
Land Use in Ada County, 1974 and 1969
Averoge size of form ocres..
Approximate land area acres,.
Prooortion in forms percent
VoKie of land and buildings ._ $1.000..
Average per farm dollars..
Average per acre dollars.,
Fcrms bv siz«:
1C to 69 acres »_ .
UO to 179 acres
ISO to 219 acres
ISO to J99 acres
S-'-O 10 999 ocres
1 COO 'o 1.999 ocres
All far mi
1974 1969
1 292 1 524
244 218 321 035
169 211
647 712 667 712
36.6 48, 1
158 035 122 987
122 318 80 700
647 383
136 208
548 634
89 90
145 211
118 137
84 85
31 39
31 24
52 43
32 23
14 19
12 11
acres..
Ocotond m cover crops, legumes, and soil-improvement grosses.
nos harvested and not pastured. _ _ _ _ _ forms
acres..
Cro*>tand in cultivated summer fallow
Cropland tdte
acres .
acres..
acres..
acres __
acres--
Forms with sole* of $2.500
and over
1974 1969
925 9«
232 034 305 253
251 323
667 712 667 712
348 45.7
137 142 105 182
148 262 111 422
591 345
54 55
302 260
77 71
140 198
103 131
81 84
30 37
30 22
52 33
31 23
14 19
11 11
Forms with soles of $2,500
and over
1974 1969
71 (MA)
15 290 16 017
3 26
205 633
11 19
6 814 429
19 116
5 256 9 730
41 93
3 015 5 225
25 11
2 375 2 593
20 8
2 016 1 659
Land in Farmi According to Use
acres..
Horvesfed cropland forms..
acres..
20 to 29 acres
50 to 99 acres ..
100 to 199 acres
200 to 499 acres _
500 to 999 acres . .
1,000 ocres and over
Cropland used only for pasture
or grazing forms--
acres
Other cropland (see text) forms..
acres..
acres
Other land (see text) forms..
1 ' t d 1 d f
acres..
Total woodland — Continued
All farms
1974 1969
1 194 1 406
118 242 122 289
1 027 1 178
73 615 81 447
139 201
163 200
149 135
157 179
226 272
131 137
48 39
10 12
4 3
766 1 018
29 120 23 849
96 290
15 507 16 993
28 17
2 709 3 153
936 1 155
123 267 195 593
1 108 1 243
80 297 84 428
acres..
acres..
Pastureland and rangeland, other than cropland and
Improved postureland and rongelar
Unimproved pastureland and range
Land in houselots, bornfots, ponds, ro
acres..
ocres..
Farms with soles of $2.500
and over
1974 1969
868 899
110 412 111 966
805 821
70 756 76 442
"1
,S [ ™
147 J
225 264
131 136
48 39
10 12
4 3
545 650
24 366 19 507
71 (NA)
15 290 16 017
25 11
2 375 2 593
698 (NA)
119 247 190 694
831 825
75 882 77 450
Forms with soles of $2,500
and over
1974 1969
6 4
359 934
698 (NA)
119 247 190 694
182 187
110 314 182 216
113 76
7 897 6 372
83 130
102 417 175 844
640 699
8 933 8 478
SOURCE: U. S. Bureau of Census 1977, pg. IV-7.
211
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for poor returns may include low prices for products, low
yields, high transportation costs to the market, high costs
for farm supplies, high labor costs, and high property taxes.
It is important to note that high property taxes at the urban/
rural fringe due to valuation of farmland at its highest
and best use are only one of the many factors influencing
the farmer considering the sale of farmland.
Demographic Factors. The most important demographic
factor in the decision to sell a farm is age of the owner.
As farmers near the age of retirement, they may attempt to
pass the farm on to a relative or willing neighbor; if this
is not possible, then farmers may consider putting their
farms up for sale.
Secondary Factors. Limitations placed on farm production
due to urban encroachment are secondary factors. These factors
may include limitations on crop dusting or fertilizer production,
traffic conflicts on farm roads, and theft or vandalism of
crops. Each of these factors can reduce farm productivity
and create a nuisance for farm operations.
Transitional Factors. Transitional factors are diffi-
cult to predict. As urban encroachment advances, an "imper-
manence syndrome" may become established and a farmer may
begin to consider moving to another location to either continue
farming or to look for a different kind of work.
Interaction of Various Factors. The interaction of
these various factors in the decision to sell a close-in
farm has been described by U. S. EPA (1977b) as follows:
"As urban pressures begin to weigh on agricultural opera-
tions, a chain of events is set in motion. Rising taxes
and development pressure begin to take their toll on neigh-
boring farms; as the number of farms begins to decline, the
important support industries, such as feed and grain dealers,
farm equipment outlets, etc., begin to leave the area ...
In time, farm labor becomes more expensive and scarce ...
The farmer slowly feels his political strength drain away
as county and local governments ... begin passing "nuisance"
ordinances ... Typically, the farmer's profit margin begins
to shrink ... For those who wish to remain in farming, the
choices come down to hanging on for as long as possible and
then selling to the highest bidder, usually a developer,
or selling out and moving the operation to an area that has
a stronger agricultural community."
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Existing Measures for Retention of Agricultural Lands in
Ada County
Federal, state, and local agencies have addressed the
problems of loss of agricultural lands, and policies have
been developed that are applicable to Ada County.
Federal. Federal activities related to agricultural
land preservation are carried out mainly by the CEQ and the
SCS. The CEQ has directed federal agencies that under all
agency actions "efforts should be made to assure that such
farmlands are not irreversibly converted to other uses unless
other national interests override the importance of preserva-
tion or otherwise outweigh the environmental benefits derived
from their protection" (Peterson 1976). Consistent with
the CEQ directive, EPA in 1978 established an agencywide
policy to mitigate or reduce adverse impacts to agricultural
lands and to encourage farmland preservation efforts at the
local and federal level that are consistent with environmental
quality goals (U. S. EPA 1978c).
Among the actions which EPA has established to implement
its policy on protection of agricultural lands, several are
related directly to the proposed projects.
-"Specific project decisions involved in the planning, design,
and construction of sewer interceptors and treatment 'facilities
shall consider farmland protection. Consistent with Agency
cost-effectiveness guidelines, interceptors and collection
systems should be located on agricultural land only if
necessary to eliminate existing discharges and serve existing
habitation.
-"Primary and secondary impacts on agricultural land shall
be determined, and mitigation measures recommended in
environmental assessments and reviews and environmental
impact statements of EPA decisions —
-"Agricultural land protection efforts of states, local
governments, or other federal programs shall be supported
through intergovernmental coordination and EPA project
reviews."
The SCS, which is concerned with maintaining the pro-
ductivity of American agriculture, has a policy to make and
keep current an inventory of the prime and unique farmland
of the nation. The SCS and CEQ are currently conducting
a national agricultural lands study to be completed in 1981.
The study is assessing policy alternatives for agricultural
land preservation.
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State. In recognition of the need to preserve the state's
agricultural resources, a preferential taxation scheme for
agricultural lands was enacted in Ada County in 1971. Under
the state law, agricultural land is taxed on current use
value rather than market value. The tax assessment is based
on income, a capitalization rate averaged over 10 years. To
qualify for the preferential taxation program, a minimum
of 5 acres under agricultural production is required. If
the parcel is less than 5 acres, the farm must gross $1,000
annually or contribute 15 percent of the applicant's income.
Peterson (1976) recently concluded a review of all state
preferential assessment programs. The review found, with
respect to retarding the conversion of farmland, preferential
assessment is "marginally effective and its costs in terms
of tax expenditures are high, in most cases so high as to
render it an undesirable tool" for maintaining farmland and
open space. The CEQ found that the principal effect of pre-
ferential assessment is to increase the profitability of
farming by reducing production costs, but that preferential
assessment affects neither the decision to sell for non-
economic reasons (death or retirement) nor the major com-
ponent of demand for land conversion -- the accessibility
to urban centers.
In addition to the preferential assessment program,
designated urban service planning areas differentiate future
urban and rural areas. The urban service planning area
designation is, however, only an indirect land use planning
tool for preservation of agricultural resources. It must
be augmented with additional land use controls to be effective.
Ada County. The preservation of agricultural land has
received considerable attention at the county level from
both the government and the public. Preservation of agri-
cultural resources was formally recognized as an important
public issue in Ada County with the formulation of goals,
objectives and policies in the 1974 Ada County Concept Plan
(ACOG 1975b). Since the concept plan was formulated, numerous
preservation programs have been recommended. The framework
for these programs is presented in Figure 12-2.
Of primary importance to Ada County's effort to preserve
agricultural lands was the adoption of the Ada County Com-
prehensive Plan (Ada County Planning Commission 1977). This
plan provides for agricultural preservation through develop-
ment policies aimed at maintaining large agricultural parcels.
The implementation of the policies has been provided through
adoption of the amended zoning and subdivision ordinances.
The effectiveness of the zoning ordinance to preserve agri-
cultural lands will be reviewed later in this chapter.
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Figure 12-2. Program for the Preservation of
Agricultural Land in Ada County
PLAN
IMPLEMENTATION
Ada County
Land Use Plan
(Revision)
Designation of
Agricultural
Lands to be
Preserved
Existing
Zoning
Regulations
and Map
V
Designation of
Urban Service
Boundary
Designate
Agricultural
Districts
(Holding-Preservation)
Proposed Adoption
of State Legisla-
lation for Prefer-
ential or Site Value
Taxation
Revision of Zoning
Regulations and Map
Based Upon Plan,
Districts & Boundaries
Existing
Subdivision
Regulations
JL
Overall Comprehensive
Planning Program
Revised, Amended
Subdivision Regu-
lations , Adoption
of PUD Ordinance
Monitoring and Review
SOURCE: AGOG 1975b.
215
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It should be noted that a distinction between rural
areas and rangeland exists in the policies of the county
comprehensive plan. Although both designated areas should
be considered significant to agricultural resource protection,
designated rural areas are, as a rule, directly involved
in the production of agricultural goods and therefore are
managed more closely by the county.
Impact: Conversion of Agricultural Land to
Urban Uses Through Provision of
Wastewater Treatment
Each of the proposed wastewater treatment alternatives
will affect to some degree the conversion of Ada County agri-
cultural lands to urban uses. The effects will differ among
the three wastewater treatment planning areas - Boise, the
Southwest area, and Eagle.
Boise Planning Area
The Boise planning area, which corresponds to the Boise
metropolitan area (excluding the Southwest area), has a sig-
nificant amount of agricultural land. According to a 1975
analysis of vacant land in the Boise metropolitan area (AGOG
1975c), 39 percent of the land in the metropolitan area (in-
cluding the Southwest) was zoned for either rural or range-
land use (all of this land is in the county portion of the
metropolitan area).
Agricultural zoning in the county portion of the Metro-
politan area involves three classifications: D-l, G-l, and
D-2; lots or parcels must exceed 5 acres to be eligible for
agricultural zoning. The D-l and G-l classification prohibit
development of nonagricultural uses. Of the total amount
of acreage in the rural and rangeland classification, only
13 undeveloped acres were zoned for D-l or G-l use (ACOG
1975c). The D-2 zone, defined as "farms lying in the unin-
corporated portion of the county which are likely to undergo
a more intense urban development", includes the remaining
undeveloped agriculturally-zoned acres, approximately 15,500
acres. This acreage represents a significant land reserve
for urban expansion.
Although zoning is a potentially effective means of
preserving farmlands, an analysis of vacant lands classifi-
cations in the county portion of Metropolitan Boise reveals
that agricultural zoning may not be serving effectively as
an agricultural land preservation tool. Rather, zoning has
been more useful as a means of identifying transitional lands
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planned for future conversion to urban use. The Ada County
Comprehensive Plan (Ada County Planning Commission 1977)
and the'wastewater facilities plan (CH2M Hill 1980c) recognize
and are proceeding on the premise that the transition of
agriculturally zoned lands from rural to urban use to accom-
modate projected growth in the Boise planning area will be
likely to occur. The potential conversion of these farm-
lands is a significant impact to the area, and EPA believes
that local planners should investigate mitigative measures
that would lessen the impact. Potential mitigation measures
are presented in the summary of impacts.
Southwest Planning Area
The Southwest area has a considerable amount of land
currently under irrigation. The impact on these lands of
future growth as projected in the Southwest community plan
(Ada Planning Association 1980) is difficult to determine
in the absence of site-specific development plans. The
maximum development density adopted in the comprehensive plan
(1 unit per 5 acres) does have, however, certain implica-
tions to the future agricultural production in the Southwest
area.
The projected population increase in the Southwest area
is 4,985 persons from 1979 to 2000 (Ada Planning Association
1980). Although this increase -is relatively small from
a total growth viewpoint, the impact on the future land use
pattern will be significant. As a result of density limita-
tions of 1 unit per 5 acres, the estimated minimum acreage
needed to accommodate new growth would be 8,308 acres (at
a density of 3 persons per dwelling unit). Such growth would
require 79 percent of the total acreage in the Southwest
area (10,500 acres). The impact on the agricultural land
use pattern would be to reduce most large-scale agricultural
operations to smaller scale "ranchette-type" farms. By
reducing the size of existing agricultural operations to
5- and 10-acre farms, the economic value (based on diversity
and economic efficiency) of agricultural activities would
be diminished.
It appears, therefore, that the projected land use pattern
based on existing density requirements will indirectly affect
the economic viability of agricultural production in the
Southwest area. As agricultural production is reduced in
the Southwest area, additional pressures to convert small-
scale farms to urban uses will likely result.
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gagle Planning Area
The future land use of the Eagle planning area is highly
uncertain. With approximately 13,000 acres of irrigated
cropland and rangeland within the Eagle area of city impact,
development could have a significant impact on the agri-
cultural resources of the area. The three population pro-
jections for the year 2000 are 10,225, 13,286, and 16,019;
each projection has different implications to the conversion
of agricultural resources. Assuming growth to 10,225 persons,
sewers would be extended to include areas to the west; this
development pattern corresponds to the current trend in popu-
lation growth.
The higher population scenarios are dependent upon the
annexation of the Middlebrook project. The Middlebrook
project, as proposed, would consume 540 acres of some of
the county's "most productive agricultural lands" (Blake
pers. comm.). This development would include 250 acres for
industrial park and 290 acres for residential uses, resulting
in a population of approximately 16,000 by the year 2000.
Without the industrial park, the population of 13,000 is
projected.
At a minimum, 250 acres of irrigated cropland would
be converted to urban uses with the construction of the
Middlebrook residential development. With the addition of
the industrial park, another 290 acres would be directly
converted. Although the direct conversion of agricultural
lands as a result of Middlebrook is substantial, the long
term implications of residential development on adjacent
agricultural resources are potentially more significant.
To realize any of these population projections, sewer
services would need to be provided. The Eagle wastewater
facilities plan will, therefore, facilitate conversion of
agricultural land surrounding Eagle to urban uses. The
amount of agricultural land which potentially would be con-
verted depends on the population scenario that is selected
for facilities planning.
Summary of Impacts
The present conditions for agricultural preservation
in the study area portion of Ada County are unfavorable.
In general, policies to retain agricultural resources through
land use programs and control techniques do not appear
effective. Development pressures are rapidly depleting the
available supply of "close-in" irrigated croplands. Although
additional major irrigation projects have been proposed for
Ada County the environmental and economic costs are considered
prohibitive (ACOG 1975b).
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Although local land use plans recognize agricultural
lands as a valuable resource, the proposed wastewater treat-
ment system for the Boise planning area will permit and accom-
modate future growth at the expense of county agricultural
lands. Even the low density residential development in the
Southwest area will eventually limit the potential for pro-
tection of agricultural land. In accordance with its policy
as stated previously, EPA encourages local planning officials
to investigate and implement all possible mitigation measures
to lessen the impact of conversion of agricultural lands.
A list of potential mitigative measures is presented below.
Potential Measures Available to Mitigate the Loss of Agri-
cultural Lands
Measures to mitigate the loss of agricultural lands
can be grouped according to basic goals. The following
list identifies six groups of possible measures which could
mitigate the loss of agricultural lands in Ada County:
1) Measures Which Affect the Amount of Urban Development.
Because urbanization of agricultural lands is a major cause
of the loss of prime agricultural land, limiting the amount
or urban development permitted would limit agricultural land
losses.
2) Measures Which Affect the Density of Development. By
increasing the density at which urban development takes place,
the amount of agricultural land lost could be reduced.
3) Measures Which Affect the Location of Urban Development.
The most direct approach to protecting agricultural lands
is to allow development only on lands not suited for agri-
cultural use, and to preserve all existing agricultural uses.
4) Measures Which Limit the Availability of Urban Infra-
structure . Limiting expansion or extension of urban services
such as roads, water, and sewers is one way of preventing
urban encroachment on agricultural la'nds.
5) Measures Which Promote Agricultural Uses. Measures
in this category represent actions which could be taken to
strengthen the competitive position of agriculture and help
it to gain better economic returns.
6) Measures Which Use Tax Policy to Protect Agricultural
Uses. These measures use tax incentives to encourage agri-
cultural uses or discourage urban uses of agricultural lands.
Differential or preferential assessment of agricultural land
is the single most commonly-employed approach to preserving
agricultural lands, but the effectiveness of this approach
is limited, especially when considering close-in agricultural
lands (Peterson 1976).
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Chapter 13
Public Services and Facilities
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Chapter 13
PUBLIC SERVICES AND FACILITIES
Wastewater planning for Boise, the Southwest area, and
Eagle is based on 20-year population growth projects. Growth
within the threa areas will increase demands on key community
services in addition to wastewater management. The objective
of this chapter is to examine, in general, the capabilities
of these other community services to accommodate projected
growth. The following community services are considered:
drainage, water supply, electricity and gas, solid waste
management, schools, police protection, fire protection,
and recreation.
Drainage
Among the public services provided to the cities and
communities of Ada County, drainage is probably the most
deficient. Further, the county faces a worsening drainage
problem in unincorporated areas due primarily to lack of
an effective mechanism to plan, construct and maintain ade-
quate urban drainage facilities. The problem is particularly
noticeable in the developing fringe areas, and is likely
to respond adversely to continuing growth. Similar problems
exist in the incorporated cities, including Boise.
The problem stems from: 1) the lack of an adopted area-
wide drainage plan, 2) the lack of consistent areawide
drainage criteria, 3) the lack of consistent enforcement
of drainage requirements concurrent with development, and
4) the absence of agencies funded to maintain existing
drainage facilities.
The drainage problem is discussed in further detail
in Appendix D. The Drainage Task Report prepared by Jones &
Stokes Associates in February 1980 upon which this material
is based, has been widely distributed and discussed at a
workshop in Boise in March 1980. The report is available
in the EPA district office in Boise.
Impacts
Increased sewage capacity and land use planning set
the stage for additional development to occur. It is likely
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that a large number of retention ponds will be built, each
serving an increment of development. Unmaintained ponds
may cause nuisances, e.g., weed growth, increased mosquito
populations, safety hazards, and failure to operate because
of sediment and debris. Expensive underground storm drain
pipes and concrete-lined channels may be required.
Mitigation Measures
The adverse impacts of new development within the
physical and institutional environment related to drainage
in Ada County can be mitigated by implementing a number of
measures. EPA may consider these mitigations for inclusion
as grant conditions on funding for the facilities covered
by this EIS.
o Designate an agency, preferably the Ada County High-
way Department (ACHD), (secondarily Ada County or
thirdly a new entity) and possibly including the
incorporated cities, to implement countywide drainage
planning, facility implementation, maintenance and
administration.
o Seek legislative clarification to provide full
drainage authority and funding to the agency for
all appropriate functions.
o Develop, adopt and implement consistent drainage
criteria for storm drain design and for provision
of flow routes for runoff from the 100-year event
without property damage consistent with the National
Flood Insurance Act.
o Prepare, adopt and implement drainage master plans
indicating flow volumes for storm drain design and
100-year flood flows, and specifying facilities
or concepts. The plans should provide for funding,
and should involve a consistent approach to the
separation or combination of storm drains with
irrigation facilities.
Community Services
Water Supply
Boise. Boise's source of domestic water supply is ground-
water. Both shallow and deep aquifers are used, with the
shallow aquifer supplying individual wells and the deep
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aquifer supplying the community system. The Boise Water
Corporation is the largest water purveyor in the Boise area,
supplying some 90 percent of the total water supply (AGOG
1973b). Annual water demand in the Boise area in 1972 was
5,865 million gallons. Demand was projected to increase
to 12,800 million gallons by 1992 (AGOG 1973b). Groundwater
supplies appear adequate to meet the demands which will be
generated by projected growth; the Boise planning area popu-
lation is projected to increase to about 212,000 by the year
2000 (APA 1978). Additional wells, water storage facilities,
and water distribution facilities will be necessary to meet
future demands.
Southwest Area. The Southwest area depends on shallow
groundwater for individual wells and deeper groundwater for
community supply. About one-half of the 4,350 residential
lots in the Southwest area receive domestic water from a
community system; the other one-half rely on individual wells.
The Boise Water Corporation supplies about 7,000 Southwest
area residents, almost half the area's population. Small
portions of the Southwest area are also served by the Ash
Park Water Company and the South County Water Company.
Irrigation water is provided by the New York Canal
which transports about 900,000 acre-feet annually (ACOG 1973b)
Three irrigation districts supply irrigation water to the
Southwest area, the New York district (serving 5,500 acres),
the Nampa and Meridian District (serving 1,500 acres), and
the Boise-Kuna district (serving 300 acres) (APA 1980).
Implementation of the "rural lifestyle" alternative
for the Southwest area would increase the area's population
to 18,985 (APA 1980). The Boise Water Corporation has not
projected any major problems in serving this growth, but
cautions that continued development using on-site systems
should include a long-term operation and maintenance program
to reduce the risks of groundwater contamination (APA 1980).
Policies in the Southwest Community Comprehensive Plan (APA
1980) encourage existing residential developments with gross
densities greater than one dwelling per five acres served
by individual systems to connect to community systems.
Eagle. Eagle uses groundwater for domestic water supply
and surface water for irrigation. Domestic water is supplied
by individual wells and by the Eagle Ranch Water Company,
which in 1977 provided well water to 300 customers (Eagle
Planning and Zoning Commission [PZC] 1978). Irrigation water
is provided by the Boise River and the Dry Creek Canal.
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Population projections for the Eagle area project growth
to between 10,225 (APA 1978) and 16,000 (with the 550-acre
Middlebrook development). As the population increases, new
wells and new water storage and distribution facilities will
be needed. The study plan for the Eagle Water and Sewer
district (J-U-B Engineers 1978) has policies to coor-
dinate future growth with water supply provision, and to
assure that expansion of water district boundaries is con-
sistent with the boundaries delineated in the Eagle Sewer
and Water Plan (Eagle PZC 1978).
Gas and Electricity
The Intermountain Gas Company supplies natural gas to
all of Ada County. Natural gas in 1979 was distributed to
32,450 customers countywide through 821 miles of gas mains
(McKinney pers. comm). Growth in Boise, the Southwest area,
and Eagle will generate additional demands for natural gas;
natural gas supplies appear adequate to meet these demands.
The Idaho Power Company supplies electricity to all
of Ada County; its service area is 20,000 square miles in
southern Idaho, eastern Oregon, and northern Nevada. The
company mainly relies on hydropower for electricity generation,
operating 16 hydro plants, in addition to a combustion turbine
and sharing ownership in a coal-fired plant. Idaho power
is currently developing an energy conservation program to
slow growth in demand. Population growth in Boise, the South-
west area, and Eagle will create additional electricity demands,
The long-term supply and demand outlook for electricity is
uncertain.
Solid Waste Management
Most of Ada County's solid waste is disposed of in Hidden
Hollows sanitary landfill, located about 5 miles north of
the Boise city limit. The landfill in 1979 was receiving
about 401 tons per day, and was projected to be at capacity
sometime during 1980 (Boise Planning and Zoning Department
1979). Solid waste in Ada County is collected by private
firms, the two largest of which are Browning and Ferris
Industries and Boise-Ada Disposal Company.
A new landfill site is being considered to meet existing
needs, as well as demands from future growth. Three sites
are currently being considered: a site off Blacks Creek
Road, a site on the first bench south of Gowen Road, and
a site between Ten Mile and Eight Mile Creeks (Boise Planning
and Zoning Department 1979).
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Schools
Boise. The Boise School District currently operates
26 elementary schools, 5 junior high schools, and 4 senior
high schools. Population growth in Boise will increase school
enrollments and the need for additional schools.
Southwest Area. Most of the Southwest area is served
by the Meridian and Boise School Districts, which together
operate four elementary schools and one junior high. Pre-
sently, all schools in the Southwest area have student en-
rollments in excess of their capacity (APA 1979a).
Under the Southwest Community Comprehensive Plan "rural
lifestyle" alternative, it is projected that one additional
elementary school would be needed, but that the existing
junior high would be sufficient to accommodate projected
growth (APA 1980). Policies in the plan provide for
developer dedication of land or payment of fees for the
acquisition and development of school sites, but the feasi-
bility of implementing these policies is questionable (APA
1980).
Eagle. Presently, the only school within Eagle is an
elementary school operated by the Meridian School District;
this school was over-enrolled in 1977. Junior and senior
high school students are currently bused to schools in the
Meridian area (Eagle PZC 1978).
Growth in the Eagle area will result in increased school
enrollments, requiring new schools and increased school
expenditures. According to the Eagle Comprehensive Plan
(Eagle PZC 1978), two additional elementary schools and one
high school would be needed to meet the enrollments which
would be produced by a year 2000 population of 10,225. If a
higher population projection of 16,000 were realized, addi-
tional school impacts would occur.
Police Protection
Boise is provided police protection by the Boise Police
Department; the Southwest area and Eagle are served by the
Ada County Sheriff's Department. Growth in the three planning
areas will increase demands for police protection.
In the Southwest area, the current officer-to-population
ratio is below the ratio of 0.67 officers per 1,000 population
recommended in the Southwest Community Comprehensive Plan
(APA 1980). By the year 2000, about five additional officers
would be needed to meet this officer-to-population objective
under the rural lifestyles alternative, at an annual cost
of about $133,600 (APA 1980).
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Fire Protection
Boise. The Boise Fire Department operates a number
of fire stations, each intended to serve a 1.5-square-mile
area. There is currently adequate fire flow within the city
and response time is considered generally adequate (Boros
pers. comm.). Additional fire stations may be needed to
meet the fire protection needs of the growth projected for
Boise.
Southwest Area. The Southwest area is provided fire
protection by the Whitney Fire District which operates one
fire station on Overland Road. Many portions of the area
currently experience water supply or water pressure problems.
The limited growth projected for the Southwest area under
the "rural lifestyle alternative" probably will not require
the construction of a new fire station (APA 1980) . Policies
in the Southwest Community Comprehensive Plan encourage pro-
vision of adequate fire flows in the future (APA 1980) .
Eagle. Eagle is provided with fire protection by the
Eagle Fire District, which is staffed by volunteers. Future
growth to 10,225 would require an additional fire station
to be built and the acquisition of additional equipment (Eagle
PZC 1978). If the Middlebrook project were approved, resi-
dential fire protection needs would increase further, and
special firefighter training and equipment would be needed
to provide industrial fire protection.
Recreation
Boise. Two large community parks along the Boise River
(Ann Morrison and Julia Davis Parks) provide regional recrea-
tion opportunities for Boise residents. Boise also has
smaller numerous neighborhood and community parks. In the
future, the Boise River "greenbelt" will continue to be the
major focus of recreation in Boise, and additional parks
will continue to be provided as Boise's population grows
(Boise Planning and Zoning Department 1979).
Southwest Area. Currently, recreation facilities in
the Southwest area are limited to a 5-acre neighborhood park.
The Southwest area has mainly relied on county and City of
Boise park facilities and on school playgrounds to satisfy
recreational needs. Under the "rural lifestyle" alternative,
an additional 31 acres of neighborhood parks would be needed
but a new community park may not be needed (APA 1980).
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Eagle. Eagle presently has no public parks, but is
in the process of developing several small parks. The large
population increases projected for Eagle will generate the
need for more and larger parks in the future.
Mitigation Measures
In an effort to coordinate growth and the provision
of public services, local agencies within the three planning
areas have developed or are in the process of developing
public services plans and policies. To the extent that these
plans and policies are implemented, the potential adverse
impacts of growth on public services will be mitigated.
If public services plans and policies are not imple-
mented, local service deficiencies could result, but these
are unlikely to be of sufficient magnitude to significantly
affect the growth rates of the three planning areas. At
this time, development of additional mitigation measures
related to public services does not appear warranted as part
of this EIS.
Fiscal Overview
Introduc t ion
Between 1975 and 2000, Ada County is expected to more
than double its population, growing from 139", 400-289,000
residents. This growth, which wastewater facilities would
in part accommodate, will require significant expenditures
of both public and private funds in order to provide the
services needed by present and new residents. One of the
many underlying issues in considering regional growth relates
to the ability of local public service agencies to pay for
that growth.
Of particular concern is the effect of 1978 state
Initiative One limiting property taxes to 1 percent of market
value. At the present time, the fact that the Idaho State
Legislature has not yet enacted a detailed program to imple-
ment the initiative both clouds the long run future and com-
pounds the short run fiscal difficulties of local governments
in Ada County.
This section summarizes existing fiscal conditions and
the fiscal outlook for each of the four areas addressed by
the wastewater facilities plan: Ada County, the City of
Boise, the City of Eagle, and the Southwest area. A more
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detailed discussion of the existing fiscal structure and
the fiscal outlook is included in Appendix B in this report.
Ada County
As a result of Initiative One and less construction-
related fees, Ada County revenues have fallen short of earlier
expectations. The county has responded by trimming some
staff and services. If the current situation is prolonged,
a reduction in nonmandated services is likely-
Looking beyond the immediate future, it appears that
the county will be affected by fiscal constraints in terms
of its future development policies. There will be a reluc-
tance to permit discontiguous development, a closer evaluation
of the public costs of new development, and review of policies
to encourage new development to annex to existing municipalities
and to obtain city rather than special district services.
In general terms, the philosophy of the county will increasingly
be to support municipal growth while unincorporated lands
would be retained in rural uses. The implications of this
approach in terms of the spatial distribution of growth are
plain. Whether such a policy would also serve to inhibit
growth is less clear.
City of Boise
Boise has felt the impact of Initiative One more severely
than other jurisdictions because it operates on an accrual
basis and because its property had already been revalued
up to near the state-mandated limit at the time the initiative
passed. Certain additional sources of revenues seem likely
to be tapped in the future and Boise will likely continue
to receive more state and federal funds, as a proportion
of its budget, than do the other general purpose governments
discussed.
The fiscal crunch has underlined the practicality of
some of Boise's planning policies, particularly the preference
for infill development in the southeast and (to a lesser
extent) the northwest. This growth corridor is the most
easily serviced by municipal agencies and in many cases the
infrastructure to support new development in these areas
is already in place. Growth elsewhere, particularly to the
west and southwest, will be more closely scrutinized in the
future, with: (1) fewer annexations, (2) preference given
to contiguous development, and (3) a close tie-in between
long-term physical development planning and capital improvement
planning to assure efficiency and minimum public cost.
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City of Eagle
The preliminary 1980 census indicates that approximately
2,600 persons currently reside in the City of Eagle. By
the year 2000, the population is projected to increase to
13,286 (APA 1980). The projected growth in the Eagle area
is not expected to decrease as a result of current fiscal
problems primarily because the present and near-term scale
of operation in the City of Boise will likely be quite modest,
The present structure of urban service provision (most ser-
vices are provided by special districts charging user fees)
partially insulates the city from the more severe effects
of Initiative One. Although much concern has been expressed
over Eagle's future growth, it appears to be more of a
regional planning concern than a potential fiscal problem.
However, special districts providing services to portions
of Eagle may encounter their own fiscal problems in extending
services.
Southwest Area
Initiative One has been one important factor influencing
the recent reassessment of future growth in the Southwest
area. The cost of providing urban services to the dispersed
developments that currently characterize the area, has proven
to be higher than anticipated. These costs have contributed
to the community's resistance to construction of public
wastewater facilities.
The Southwest area is located in the unincorporated
county and is served by a number of special service districts.
As a result, the fiscal outlook for the Southwest area is
difficult to assess. It does appear, however, that the
combination of lower property tax revenues and an increasing
awareness of the cost of urban services will result in slower
growth than anticipated, at least in the near term.
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Chapter 14
Archaeological and Cultural
Resources
-------
Chapter 14
ARCHEOLOGICAL AND CULTURAL RESOURCES
Introduction
Section 106 of the National Historic Preservation Act
requires the head of any federal agency with jurisdiction
over a proposed federal or federally-assisted project to
consider the impact of the project on sites, districts or
structures included on, or eligible for inclusion on, the
National Register of Historic Places prior to taking action
on the project. The federal agency must also provide the
Advisory Council on Historic Preservation the opportunity
to review the cultural and historic implications of the pro-
posed project prior to action.
Regulations implementing Section 106 identify the pro-
cedure^for evaluating potential impacts on properties on
or eligible for the National Register. This includes:
1) identifying properties within the project's area of impact
that are on or eligible for inclusion on the National Register
of Historic Places (this includes consulting the National
Register and the State Historic Preservation Officer [SHPO]);
2) determining whether properties on or eligible for the
National Register might be affected by the project; 3) deter-
mining if the effect is adverse; 4) notifying the Advisory
Council and the SHPO of the findings of the impact analysis;
and 5) proceeding with the consultation process if an adverse
effect is anticipated.
The annual listings of historic properties appearing
in the March 18, 1980 Federal Register and monthly supple-
ments have been reviewed and the Idaho State Historic Pre-
servation Officer (SHPO) has been contacted with respect
to possible historic and cultural resources which may be
affected by the wastewater treatment facilities proposed for
the Eagle Water and Sewer District (EWSD) and the City of
Boise.
Impacts
As a result of consultation with the Idaho SHPO and
review of the annual listings of historic properties, EPA
has determined that none of the alternatives evaluated for
providing wastewater facilities for the EWSD and the City
of Boise will affect any historic properties included in
the National Register of Historic Places. In addition, it
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has been determined that there are no properties within the
area of environmental impact that will be affected which
are eligible for inclusion in the National Register.
In further consultation with the Idaho SHPO, the state
archeologist has determined that there are no cultural
resources located within the EWSD project area. This deter-
mination is based on an archeological field reconnaissance
of the proposed construction site.
The proposed City of Boise wastewater treatment facilities
have also been reviewed by the state archeological officer.
The primary area of concern appears to be along the Boise
River. Of the numerous archeological surveys conducted along
the river, the only site found to date is a large trash deposit
located in the Julia Davis and Ann Morrison Parks. Proposed
interceptor alternative alignments will, however, run near
the river; therefore, the state archeologist would like to
periodically inspect the open trenches and dirt removed from
them to record buried archeological sites and recover any
artifacts found (see letters at end of this chapter).
Based on this request, EPA will require the City of
Boise to provide access to Idaho SHPO representatives for
inspection of trenches and excavated materials. This require-
ment will be included in a Step III (construction) grant
condition. The state archeologist has concluded the proposed
sludge pipeline will have no effect on any sites.
If any changes in proposed construction location
associated with the proposed Eagle or Boise facilities
should occur, the state archeologist will be notified and
appropriate action taken to comply with Section 106.
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January 21»
;'r. '*. "avnr- ^ibbs
Project Planner
J-U—TJ Engineers, Inc.
250 S. Pecc>>wood Avenue, Suite 1
Rolse, IdaJio 83705
Re: raplc "nter and l-«wcr
"r.
Aa archaeolo-'ical ^iolJ ri?connni.Rsancd of the
construction *> i to. 1^ t^e i'aRlc r'ater and f-'^xrcr T
Man been corjducte'.' . nfnco no cultural repourcos
found, thin ^rolrct r:Voul'1 h.°vo no effect or anv nrcbar -
domical nr Mftoric nttc°. . i'ovover, fshonld t1 err ^e an
c^anrcp in the pro-pored con.stfuction location ".Ica^e con
sult with 'J.s further. TK-ml' vou for your roonor-ition .
•'••fncerelv ,
T'-opf.-! J. Clrcen
.State. Arch.ieolo^iet
State Historic Presprvntion Office
cc: Hal p.issell, Jones and PtoV.es Associates
233
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December 22, 1980
Ms. ,Iarp,arct L. Zitnne.rnan
Cu2:: in 11
n 700 Clear-water Lane
^ Cox 3748
Jioisc, Idai.o 53707
Ucar fta. r.irj-^
'.'a have finally reviewed t:.o - apn you sent for
the uoir-tcnl surveys alcnp
the rivo.r arJ i;rve "ct to find £:.r:y fiJtc-T otixtr tlian
tMe lar;-c Mrtoric tnr,!: ck-riorltr- In Ju]1;i -.iavip
nnd A;tn ?'orrlnon paries.
The Glud"e plpelircr; /ill h.'.ve no effect 011 anv
archaeolo'-ical or hj: coric sLter..
For the inte.rcrrtor.T nin:i3n ncr.r the river v> .-'o
want to periodically f:ir,-ect tl:c open trenc'ien nnd
the dirt reroved Trot t',.-.T' to record burled arch-
aeological sites and recover any artifacts uncovered.
No arbhaeoloc leal excavation or slow tioi-me of t5:e
construction will be needed.
Sincerely,
Thornsg J. Greeh
State Archaeologist
State Historic Preservation Office
234
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Chapter 15
Summary of Significant Impacts
and Mitigations
-------
Chapter 15
SUMMARY OF SIGNIFICANT PROJECT RELATED IMPACTS
In this chapter the alternatives proposed for the City
of Boise and the Eagle Water and Sewer District (EWSD) waste-
water treatment projects are reviewed and the significant
impacts of each are briefly discussed and summarized under
a number of environmentally important headings.
These impacts are based upon an evaluation of the general
nature of the proposed project alternatives. Where detailed
routes have been identified for the location of interceptors
and sludge pipelines we have drawn upon specific information
provided in the facilities plans for Boise (CH2M Hill 1980a).
See Figures 4-3, 4-4, and 4-5 for route names and locations.
t Several issues remain to be more completely analyzed
for the Final EIS. These include a fuller analysis of in-
direct impacts of growth relating to air quality, public
services, and fiscal and employment factors in the communities
involved. Also, more complete analyses of specific traffic
and transportation patterns will be done.
Wastewater Treatment and Disposal Impacts
Boise River
Impacts. There should be no significant adverse impacts
resulting to the Boise River from the proposed wastewater
treatment plant at the Cities of Boise and Eagle, provided
that the l-in-10 year low flows used in the Boise facilities
designs are actually implemented.
Residual chlorine levels in the Boise River will be
decreased due to installation of dechlorination. Increased
nutrient loadings to the Boise River may cause greater algal
growth levels and greater dissolved oxygen sags in the lower
river. The quantitative extent of the impact is not known.
Mitigation. The l-in-10-year low flow used in designing
facilities expansion needs to be assured in order that the
receiving water quality criteria can be met. Detailed plan-
ning should not proceed until the flow issue is resolved
23.5
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Growth Impacts
The proposed projects will provide capacity to accom-
modate growth. This growth will cause indirect impacts upon
a number of environmental features. These impacts have been
described in previous chapters and are summarized under the
following environmental topic headings where relevant.
Air Quality
Impacts. Increased growth accommodated by improved
wastewater treatment in the Boise area will result in dete-
rioration of air quality. Estimates of future air pollu-
tion potential are presented in Table 7-9 which makes it
clear that CO problems can be expected to persist at least
to the year 2000 in several portions of the Boise Metro-
politan Area.
To meet the 1987 deadline established by the Clean Air
Act, projected 1987 emissions must be reduced by as much
as 53 percent in some community planning areas, e.g., Central
Bench, CBD and West Bench.
The analyses presented above have not included the
effects of any vehicle inspection and maintenance program
for Ada County. If such a program were implemented, pro-
jected vehicle emissions would be reduced by about 20-25
percent. This level of emission reduction would still be
insufficient to provide for attainment of the 8-hour CO
standard in the Central Bench, CBD, West Bench, and Warm
Springs areas.
Mitigation. The APA is currently reviewing a number
of additional measures which could be implemented to help
achieve air quality standards through Ada County. These
measures include:
o Improved public transit (short-term and long-term
programs).
o Carpool/vanpool programs.
o Park and ride facilities.
o Traffic flow improvements through signalization
programs, intersection design changes, added road
lanes; many specific roadway and intersection
improvements are already accounted for in the
emission forecasts (see Appendix A).
o Exclusive bus and carpool lanes.
236
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o Parking management programs (controls on the loca-
tion and duration of on- and off-street parking;
parking costs; supporting park and ride programs;
facility design and operation; etc.).
o Controls on extended vehicle idling at drive-in
facilities.
o Pedestrian malls.
o Improved bicycle facilities.
o Employer actions to support transit, carpool/van-
pool programs,. bicycle usage, flexible work
schedules, etc.
These measures will require further study to determine
the effectiveness of each measure to aid in the achievement
of air quality maintenance standards.
Conversion of Agricultural Land to Urban Uses
Impacts. The proposed wastewater treatment systems
for the Boise planning area will permit and accommodate
future growth at the expense of county agricultural lands.
Even low density residential development in the Southwest
area will eventually limit the potential for protection of
agricultural lands.
In accordance with its policy, as stated previously,
EPA encourages local planning officials to investigate and
implement all possible mitigation measures to lessen the
impact of conversion of agricultural lands.
Mitigations. The following list identifies six groups
of possible measures which could mitigate the loss of agri-
cultural lands in Ada County:
1) Measures Which Affect the Amount of Urban Development.
Because urbanization of agricultural lands is a major cause
of the loss of prime agricultural land, limiting the amount
or urban development permitted would limit agricultural land
losses.
2) Measures Which Affect the Density of Development. By
increasing the density at which urban development takes place,
the amount of agricultural land lost could be reduced.
3) Measures Which Affect the Location of Urban Development.
The most direct approach to protecting, agricultural lands
is to allow development only on lands not suited for agri-
cultural use, and to 'preserve all existing agricultural uses.
237
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4) Measures Which Limit the Availability of Urban Infra-
structure . Limiting expansion or extension of urban services
such as roads, water, and sewers is one way of preventing
urban encroachment on agricultural lands.
5) Measures Which Promote Agricultural Uses. Measures
in this category represent actions which could be taken to
strengthen the competitive position of agriculture and help
it to gain better economic returns.
6) Measures Which Use Tax Policy to Protect Agricultural
Uses. These measures use tax incentives to encourage agri-
cultural uses or discourage urban uses of agricultural lands.
Differential or preferential assessment of agricultural land
is the single most commonly-employed approach to preserving
agricultural lands, but the effectiveness of this approach
is limited, especially when considering close-in agricultural
lands.
Public Services and Facilities
Impacts. The adverse impacts on public services from
growth accommodated by wastewater facilities will be most
significant in areas where the existing level of public
service is currently deficient. In the Boise metropolitan
area, the outlying areas are presently experiencing some
public service deficiencies, primarily in police and_fire
protection and schools. In the Eagle area, adverse impacts
on most public services will result as growth extends beyond
the central city planning area. Additional medical care
and hospital facilities will be required.
Mitigation. Existing Ada County and Boise policies
should be implemented to avoid further compounding existing
public service deficiencies. These policies encourage con-
centrating future development in areas already provided with
public services, or in areas contiguous to serviced develop-
ments .
Urban service policies are implemented in part by desig-
nation of urban service planning areas in Ada County- Most
residential, commercial, and industrial development is
encouraged by the Ada County Comprehensive Plan to occur
in urban service planning areas.
The policy plan for the Boise Metropolitan Area also
uses the urban service planning area as a mechanism to co-
ordinate growth and the provision of urban services.
238
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Vegetation, Wildlife and Fisheries
Impacts. Accommodated urban growth will cause the greatest
long-term impacts on wildlife. Conversion of open spaces
in the foothills and on the plain to housing and industry
will reduce the available habitat for many species. The
bald eagle and long-billed curlew are especially vulnerable
to disturbance.
Indirect impacts due to population growth will consist
of increased sediment load, and higher flood peak flows from
urbanized tributaries. Increased sedimentation of stream
gravels will lower habitat quality conditions for trout and
whitefish in the Boise River.
Mitigation.
Vegetation and Wildlife. Urbanization and recreation
within or adjacent to Barber Pool should be planned to mini-
mize bald eagle disturbance. Development, for example, should
be discouraged near the cliffs used as roosting sites, and
winter recreation should be directed toward the periphery
of the pool, rather than through the middle of it. Similarly,
development should be directed away from curlew nesting areas.
Fisheries. Implement drainage and runoff control measures
to prevent sediments from growth-related development entering
the streams and rivers.
Drainage
Impacts. Increased sewage capacity and land use planning
set the stage for additional development.
A large number of retention ponds may be built to serve
development. These may cause weed growth, increased mosquito
populations, safety hazards and may fail to operate because
of sediment and debris.
Mitigation .
o Designate an agency to implement countywide drainage
planning, facility implementation, maintenance and
administration.
o Seek legislative clarification to provide full
drainage authority and funding.
o Develop, adopt and implement consistent drainage
criteria for storm drain design and flow routes from
100-year flood runoff.
239
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o Prepare, adopt and implement drainage master plan,
specifying facilities or concepts, and providing
for funding and a consistent approach to storm drain
authorization with irrigation facilities.
Resource and Energy Use
Impacts. Population increases in the sewered area will
use energy in the residential and transportation sectors
and could stimulate consumption in the commercial and indus-
trial sectors. The principal energy sources are natural
gas, electricity, and petroleum fuels. Some geothermal energy
is used for space heating in Boise, and many residences use
wood as fuel.
Future trends in the availability and consumption of
energy resources are difficult to predict. The local avail-
ability of energy will be closely related to regional and
global trends in energy sources and supplies.
Mitigation. Institute energy conservation measures.
Traffic Congestion
Impacts. Population growth supported by increased waste-
water treatment plant capacity will add traffic loads to
the existing roadway system of the area. Roadway elements
which currently experience significant congestion may be
further impacted by additional development.
Mitigation. Develop local traffic plan considering
air quality attainment standards.
Water Resources
Impacts. As additional agricultural lands in the Boise
Valley are converted to nonagricultural uses the balance
between nitrogen and salts loadings and the volume of water
recharged to the aquifers will be adversely affected.
Under land use Plan C, rural lifestyle, it is expected
that the Southwest Boise area will retain its rural char-
f^fr^tlCS f°r the foreseeable future. It is improbable
that the anticipated growth will cause a major change in
groundwater quality and quantity. However, further data
pr°tection of ?ublic health and safety as
^iMqation Regular monitoring of shallow and deep
be cafr ^ T^' Preferably on a seasonal basis, shc-uld
e car
vide n^S rfT*. Y/n aPPr°Priate government agency to pro
purposes fUtUre Plannin9 and decision-making
240
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The APA (1980) has developed a draft comprehensive plan
which could provide the basis for a workable on-site waste
management program.
Elements of this plan include:
o Determine causes of septic tank failures in rural
Ada County -
o Modification of design criteria established by
Central District Health Department (CDHD) to
decrease the number of septic system failures.
o Establish and update map of rural Ada County which
indicates location of septic system failures.
o Establish coordinated groundwater monitoring program.
o Develop public education program for residents and
commercial establishments.
o Develop voluntary/mandatory maintenance program.
o Establish user fee schedule to fund program.
Publ-Lc Health. There should be no significant impact
upon groundwater or public health as a result of liquid
sludge disposal as proposed and described in the Boise waste-
water treatment facilities plan.
The sludge disposal method for the Eagle plant has not
been described.
Construction-Related Impacts
There are many construction-related impacts which will
be common to all the alternatives at both Boise and Eagle.
These impacts relate to the general use of equipment and
are chiefly in the categories of noise, dust, sedimentation,
and traffic. Impacts may also include physical displacement
or destruction of resources such as vegetation and wildlife.
The proposed projects involve modification or construction
of facilities at several different locations in the Boise
and. Eagle area. The significance of construction-related
impacts usually depends on site-specific conditions. Thus,
the following discussions are organized in terms of project
elements at different locations.
241
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Noise, Dust and Erosion
Impacts Figure 15-1 identifies noise levels by types
of equipment which are typically used for construction and
demolition. Most of this equipment will be necessary for
implementation of the primary treatment improvements and
pipeline construction. In addition to equipment used within
the primary plant sites, vehicles related to construction
operations will be entering and leaving the sites. Con-
struction-related vehicles will include passenger vehicles
for workers, materials transport trucks, and waste removal
vehicles.
Plant site grading and excavation of facility sites and
pipelines, demolition of abandoned facilities, vehicle movements
on unpaved roads and parking areas, and handling of debris
from construction or demolition will produce dust and expose
soil surfaces to erosion. Dust generated by construction
activities will undoubtedly be carried off-site on occasion.
South Boise Interceptors. Short-term adverse impacts
upon recreational, green belt, and park areas will occur
from the river north route, and upon a recreational area
from the river west route. Short-term adverse impacts will
result to residences along the Adams Street route, and to a
recreational vehicle park near the river east and inland
east routes.
North Boise Interceptors. Short-term adverse impacts
will result to approximately the same extent from all four
proposed North Boise interceptor routes.
Eaile. No significant adverse impacts will result from
the proposed treatment plant facilities and interceptor.
Mitigation. Noise can be minimized by requiring that
all internal combustion engines be equipped with mufflers
and baffles and be properly maintained. Construction opera-
tions should be limited to normal daylight working hours.
Vehicles should carry full loads of materials and passengers
to minimize trips.
Normal dust control measures should be followed during
construction (water sprinkling or chemical treatments such
as calcium chloride or light petroleum products for con-
struction and parking areas). Disposal areas on agricultural
land should be replanted soon after disposal of soil. Exposed
areas and spoil piles should be watered down to prevent dust.
Exposed areas which will be incidental to construction and
not required for operations should be reseeded following
construction, preferably with natural vegetation.
242
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Figure 15-1
NOISE FROM CONSTRUCTION EQUIPMENT
NOISE LEVEL (dBA) AT 50 FT
60 70 80 90 100 110
ION ENGINES
NTERNAL COMBUST
EQUIPMENT POWERED BY
1-
o
2
EARTHMOVING
o
-^
o
<
X
V)
_J
<
MATER
STATIONARY
EQUIPMENT
OTHER
COMPACTERS (ROLLERS)
FRONT LOADERS
BACKHOES
TRACTORS
SCRAPER§, GRADERS
PAVERS
TRUCXS
CONCRETE MIXERS
CONCRETE PUMPS
CRANES (MOVABLE)
CRANES (DERRICK)
PUMPS
GENERATORS
<_ COMPRESSORS
PNEUMATIC WRENCHES
JACK HAMMERS AND ROCK DRILLS
PILE DRIVERS (PEAKS)
VIBRATORS
SAWS
h
L
r
H
I
i
i
i .I .
i
i
^
•
i
i < «
i
-i
H
i
I
i
H
i
M
_i
i
' '
i
i
j
... i
i
...i
1
,i
i
i
. i
NOTE = Based on limited available data samples
SOURCE: U. S. Environmental Protection Agency, 197Ib,
243
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Traffic Disruption
Impacts. Construction activities at the primary treat-
ment plants will not directly block or otherwise disrupt
traffic patterns on adjacent streets. Movement of construction
equipment, construction materials, new facility equipment,
and construction wastes could result in temporary reductions
in traffic flow on area roadways. This would be most likely
for trucks bringing over-sized loads to the plant sites (heavy
construction equipment and new facility equipment).
Excavation and placement of interceptors and sludge
pipelines will temporarily disrupt traffic. Trenching adja-
cent to or within agricultural'areas will temporarily restrict
access and movement of agricultural equipment. Pipeline
routes will intersect roads, requiring an open cut across
pavement. Motor vehicle flow will be temporarily detoured
or restricted for jackhammer and trenching operations across
roadways.
Mitigation. Trucks with over-sized loads should be
routed to the construction site so as to avoid peak traf-
fic periods and major local arterials. On-site parking
areas should be provided for construction employees.
Vegetation and Wildlife
Impacts
Eagle. The proposed plant site is in one of the largest
riparian communities along the river. Construction of the
proposed Eagle facilities treatment ponds will eliminate
a minimum of 15 acres of riparian habitat along the Boise
River, in addition to habitat lost by buildings, roads, and
pipelines.
Loss of the riparian habitat will reduce the wildlife
population inhabiting the site, especially water-associated
birds and mammals.
Alternative A (oxidation ditch) would cause a loss of
riparian habitat.
Alternative B (pump to West Boise treatment plant) would
destroy not only wildlife habitat of the site, but would
destroy habitat over a distance of 19,000 feet during pipe-
line construction. This pipeline would cause significant
impacts to a great blue heron rookery.
Alternative C (irrigation utilizing effluent) would
destroy not only the riparian habitat at the plant treatment
site, but would destroy up to 50 acres of wildlife habitat,
depending upon location of storage ponds.
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Alternative D (rapid infiltration with discharge to
the river, lagoon and treatment plant)'would destroy riparian
habitat. Infiltration basins would destroy wildlife habitat.
Boise. Riparian habitat will be destroyed by certain
of the proposed interceptor and sludge line routes which
may be located near the river.
Of the proposed South Boise interceptor routes, the
river north route would result in the loss of approximately
7 acres of riparian vegetation near river mile 51, near the
Lander Street treatment plant, and in the Veterans' Memorial
State Park.
The river west route would destroy more than 5 acres
of riparian vegetation in a narrow strip along the river
if located near the bank.
Both the Chinden and Adams routes would pass through
areas already highly disturbed and there should be no signi-
ficant impact upon vegetation.
The proposed North Boise interceptor routes would have
significant impact only where Main A would cross Eagle Island
and the river, and where Main E crosses the river. There
would be fewer impacts from the other routes which generally
are located on irrigated farmlands.
The greatest impact would probably be the crossing of
Eag'le Island which would disrupt vegetation and may disturb
an active great blue heron rookery. Impact would be greatest
during the heron and waterfowl nesting season (February
through June).
Construction could conflict with bird hunting seasons
in the fall.
The destruction of riparian habitat may generally be
regarded as a potentially significant short-term impact. Vege-
tation will be lost, and associated animal life will be lost
or disturbed.
The long-term impacts will not be significant if vege-
tation is reestablished.
However, if any of the corridor routes are used for
other land uses, such as bikeways, then there would be a
significant long-term adverse impact upon the wildlife due
to elimination of habitat and to disturbance by humans.
Mitigation. Prior to any decision to provide federal
assistance to the City of Eagle for wastewater treatment
facilities, EPA and the City of Eagle will evaluate alter-
native sites that may either avoid or lessen the impact to
245
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the existing wetland. If, in its evaluation, EPA and the
City of Eagle find that no other feasible alternatives exist,
mitigation measures aimed at protecting the wetland will
be proposed and coordinated with the U. S. Fish and Wildlife
Service. The results of the evaluation will be included
in the Final EIS.
Interceptor and sludge lines proposed for Boise should be
located to avoid riparian habitat where feasible and the
vegetation within the corridors should be restored.
Other land uses should not be established in areas where
significant wildlife use exists, such as the great blue heron
rookeries.
Fisheries
Impacts. There is some potential for significant impacts
resulting from river crossings by interceptors and sludge
pipelines. All of the Boise interceptor and sludge pipeline
alternatives and the Alternative B of the proposed Eagle
plan would require at least one river crossing. River cros-
sings will result in temporary adverse effects on aquatic
biota. Fall spawning runs of anadromous fish species may
also be affected. Species will be displaced from the area
of equipment operations, and sedentary species or fish eggs
could be destroyed. Sedimentation from excavation and river
bottom disturbance will affect fish, causing avoidance of
silted waters and possible gill irritation. Insects which
serve as food for fish will also be affected. Siltation
will also cause smothering of fish eggs in downstream areas.
These adverse impacts are not expected to be significant
if stream crossings are conducted as advised by the Idaho
Department of Fish and Game and the U. S. Army Corps of Engi-
neers. All stream crossings will require appropriate permits
from the Idaho Department of Fish and Game and the U. S.
Army Corps of Engineers.
Mitigation. Specific mitigation measures should be
developed in consultation with the Idaho Department of Fish
and Game and the U. S. Army Corps of Engineers. The Corps
has issued a Nationwide General Permit for the placing of
dredged or fill material for backfill or bedding of utility
line crossings provided the following conditions are satisfied:
"a. The watercourse is returned to preconstruction
bottom contours and all excess material is removed
to an upland disposal area.
b. That the discharge will not be located in the proxi-
mity of a public water supply intake.
246
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c. That the discharge will not occur in areas of con-
centrated shellfish production.
d. That the discharge will not destroy a threatened
or endangered species as identified under the En-
dangered Species Act, or endanger the critical
habitat of such species.
e. That the discharge will not disrupt the movement
of those species of aquatic life indigenous to
the water body.
f. That the discharge will consist of suitable material
free from toxic pollutants in other than trace quan-
tities .
g. That the discharge will not occur in a component
of the National Wild and Scenic River System or
in a component of a State Wild and Scenic River
System.
The following management practices should be followed
to the maximum extent practicable to minimize the adverse
effects of the discharge on the aquatic environment:
a. Discharges .in spawning areas during spawning seasons
should be avoided.
b. Discharges in wetland areas should be avoided.
c. Heavy equipment working in wetlands should be
placed on mats.
d. Discharges into breeding and nesting areas for
migratory waterfowl should be avoided."
Archeological and Cultural Resources
Impacts. No cultural resources have been identified
at the proposed Eagle treatment site or along the proposed
Boise interceptor or sludge pipeline routes.
Historic trash deposits have been found at Julia Davis
and Ann Morrison Parks but these parks will not be adversely
impacted by the project.
Excavations for proposed treatment facilities or pipelines
have the potential for disturbing previously unknown historical
or archeological sites.
Mitigation. Excavation in areas designated by the state
archeological officer as potential sources of archeological
artifacts should be conducted according to advice from profes-
sional archeologists. The state archeologist should be kept
247
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informed of the progress of the proposed project, and the
opportunity provided for professional examination of excavated
sites and materials (see Chapter 14).
Disruption of Effluent Flow
Impact. Disposal of effluent during phases of new con-
struction of pipelines and other facilities could be impaired.
Mitigation. Adverse impacts may be avoided by retaining
existing pipelines, pumping stations, etc., until new facilities
are put into operation.
New pump stations, for example, may be built separately
and tied into existing pipelines during periods of low flow
in the system. Temporary storage within the pipelines and
emergency holding ponds may be used as needed while the new
facilities are connected to the existing pipelines.
Resources and Materials
Impacts. All of the proposed alternatives will require
the irretrievable expenditure of energy and materials in
the construction and operation of the wastewater treatment
facilities and the interceptor and sludge lines.
Mitigation. Recovery of methane gas from anaerobic
digestion to aid in operating equipment in wastewater treatment
facility.
Reduce infiltration/inflow in sewer lines, and establish
water conservation program (reduce pumping loads).
No-Action Alternative
Boise
If the proposed wastewater treatment plans are not imple-
mented, the present water quality problems would continue,
and projected population growth would have no sewer service,
leading to possible additional water quality problems. In
turn this would lead to detrimental impacts upon fisheries
and recreational uses of the Boise River.
Increased growth without sewering could result in increased
waste discharge to septic tanks with significant threat of
pollution to area waters. A building moratorium may result
from this threat.
248
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Boise residents may be required to pay fines and suffer
the loss of federal funds for public projects if NPDES standards
are not met.
If no action is taken to implement the proposed wastewater
treatment plan, conditions would remain as they are, resulting
in continuing violation of the District's NPDES discharge
permit, and with no provision for improvement in quality
of effluent being pumped into the Boise River.
With no plan implementation there would be no new impacts
at the proposed site. However, adverse impacts of the existing
system would continue, including those related to water quality
and community growth limitations. Any new growth would have
to rely upon on-site waste disposal systems, which would
increase risk of water pollution and which would require
low density land use with possible adverse economic impacts
upon the community, and indirect adverse impacts upon fish
and wildlife habitat.
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LIST OF REPORT PREPARERS
U. S. Environmental Protection Agency - Region 10
Elizabeth Corbyn - Chief, Environmental Evaluation Branch;
Seattle, Washington.
Area of EIS Responsibility. Coordinates EIS preparation
efforts with other EPA Region 10 environmental evaluation
functions.
Roger Mochnick - EIS Preparation Coordinator, Environmental
Evaluation Branch; Seattle, Washington.
Area of EIS Responsibility. Oversees all EIS preparation
efforts for EPA Region 10.
Norma Young - Project Monitor, Environmental Evaluation
Branch; Seattle, Washington.
Area of EIS Responsibility. Principal monitor and
reviewer of Ada County/Boise EIS.
Mark Masarik - Urban Area Coordinator EPA Operations Office,
Boise.
Area of EIS Responsibility. Coordinates efforts of
EIS team with local government agencies and contractors.
Jones & Stokes Associates, Inc.,
Sacramento, California
Charles R. Hazel - B.S., M.S., and PhD., Fisheries Biology.
Formerly with California Department of Fish and Game
as Director of Water Pollution Control Laboratory.
As Vice President of Jones & Stokes Associates, Inc.,
has managed numerous environmental studies and reports
and served as expert consultant in fisheries and
water quality ecology -
Area of EIS Responsibility. Program director.
Harold D. Bissell - B.A., Biochemistry, M.A., Zoology.
Formerly with California Department of Fish and Game
as wildlife biologist; leader of wildlife nutrition
laboratory; and assistant chief of coastal resources.
Also chairman of state power plant siting committee,
and former executive secretary of California Interagency
Council for Ocean Resources. As environmental scientist
251
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with Jones & Stokes Associates, Inc., contributor to,
and manager of, numerous environmental studies and
impact statements and reports.
Area of Responsibility. Project manager.
Robert D. Sculley - B.S., Zoology, M.S., Ecology. Staff
ecologist with special expertise in air quality analysis
including modeling, development of emission inventories
and projection of air quality changes. With Jones &
Stokes Associates, Inc., for 9 years with varying project
management, and resource planning and environmental
impact analysis experience.
Area of EIS Responsibility. Project coordinator,
air quality.
Douglas P. Albin - A.B., Zoology, M.S. Fisheries.
Area of EIS Responsibility- Fisheries and hydrology.
Nicholas Cimino - B.A., Political Science.
Area of EIS Responsibility. Project coordinator,
Boise, Idaho.
Jeffrey D. Civian - B.S., Renewable Natural Resources.
Area of EIS Responsibility. Air quality.
Carol Cunningham - B.Sc., Geography -
Area of EIS Responsibility. Editing and coordinating.
Michael Durkin - B.A., Geography.
Area of EIS Responsibility. Air quality .
Patricia S. French - B.A., French, M.L.S., Library and
Information Studies
Area of EIS Responsibility. Preparation of reference
listing.
Glenn Gephart - B.A., Biological Sciences and Ecology,
M.S., Wildlife Science.
Area of EIS Responsibility. Vegetation and wildlife.
Albert Herson - AICP, B.A., Psychology, M.A., Psychology,
M.A., Urban Planning
Area of EIS Responsibility. Land use studies, population
issues and community services.
252
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JoAnne Sorenson - B.A., Biology, M.A., Biology.
Area of EIS Responsibility. Editing.
Curtis E. Spencer - P.E.
Area of EIS Responsibility. Drainage and hydrology.
Thomas C. Wegge - B.A., Urban Studies, M.S., Environmental
Economics.
Area of EIS Responsibility. Land use, growth implica-
tions and population projections.
Jones & Stokes Associates, Inc.,
Seattle, Washington
Jonathan H. Ives - B.B.A., Wildlife Management, M.S.,
Wildlife Biology.
Area of EIS Responsibility. Hydrology, wastewater
alternatives, and water quality management.
Culp-Wesner-Culp
Cameron Park, California
Robert Williams - B.S., Civil Engineer, M.S., Sanitary
Engineer.
Area of EIS Responsibility. Evaluation of facility
plans, description of existing facilities.
Justin Faisst - B.S., Civil Engineer, M.S., Environmental
Engineer.
Area of EIS Responsibility. Evaluation of facility
plans, description of existing facilities.
H. Esmaili and Associates, Inc.,
Berkeley, California
Houshang Esmaili - Doctor of Engineering, Water Resources
Engineering.
Area of EIS Responsibility. Overall coordination,
supervision of groundwater/water studies.
Nicholas Johnson - M.S., Hydrology.
Area of EIS Responsibility. Hydrology and groundwater
quality-
253
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Barry Hecht - PhD., Candidate in Geography.
Area of EIS Responsibility;- Hydrogeology and ground-
water quality.
Roger Abraham - M.S., Soil Science.
Area of EIS Responsibility. Nonpoint source loadings.
Gruen Gruen + Associates
San Francisco, California
Roberta Mundie - Master of City Planning.
Area of EIS Responsibility. Population and fiscal
impacts analysis.
Suzanne Lampert - Master of Public Affairs and Urban Planning.
Area of EIS Responsibility. Population and fiscal impact
analysis.
G-ological Drafting Service,
Sacramento, California
Steve Fleming - Extensive Cartographic Experience.
Area of EIS Responsibility. Report graphics.
254
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ACRONYMS AND ABBREVIATIONS
ACHD
AGOG
APA
BEA
BOD
BWQ
CaC03
CDHD
CEQ
cf s
CO
DED
EIS
EPA
ESDI
EWSD
FEMA
FERC
IDFG
IDHW
IPCo
IWRB
Ibs/ac
MGD
mg/1
nunhos/cm
N
NAAQS
NEPA
NH3
NOI
N03-N
NPDES
Ada County Highway District
Ada Council of Governments
Ada Planning Association
Bureau of Economic Analysis
biological oxygen demand
Bureau of Water Quality
calcium carbonate
Central District Health Department
Council of Environmental Quality
cubic feet per second
carbon monoxide
Demographic and Employment Distribution
Environmental Impact Statement
U. S. Environmental Protection Agency
Emission Source Density Index
Eagle Water and Sewer District
Federal Emergency Management Agency
Federal Energy Regulatory Commission
Idaho Department of Fish and Game
Idaho Department of Health and Welfare
Idaho Power Company
Idaho Water Resources Board
pounds per acre
million gallons per day
milligrams per liter
millimhos per centimeter
nitrogen
National Ambient Air Quality Standards
National Environmental Policy Act
ammonia
Notice of Intent
nitrate measured as N
National Pollutant Discharge Elimination System
255
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OMB
ppm
SHPO
SRMF
SWIDD
TSS
201
208
USGS
USSCS
USPA
Office of Management and Budget
parts per million
State Historic Preservation Officer
Stream Resource Maintenance Flow
Southwest Interim Development District Ordinance
total suspended solids
Section 201 of the Clean Water Act
Section 208 of the Clean Water Act
U. S. Geological Survey
U. S. Soil Conservation Service
Urban Service Planning Area
256
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EIS DISTRIBUTION LIST
Federal Agencies Advisory Council on Historic Preparation
U.S. Department of Agriculture
Farmers Home Administration
U.S. Department of Commerce
National Marine Fisheries Service
U.S. Department of Defense
Corps of Engineers, Seattle District
U.S. Department of Health and Human Services
U.S. Department of Housing and Urban Development
U.S. Department of the Interior
Fish and Wildlife Service
U.S. Bureau of Reclamation
U.S. Department of Transportation
Federal Highway Administration
Idaho State Agencies Central Health District
Division of Environment
Air Quality Bureau
Department of Fish and Game
Department of Planning and Community Affairs
Department of Transportation
Department of Water Resources
State Clearinghouse
Ada County Board of County Commissioners
Engineer
Highway District
Planning Association
Zoning Department
257
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City of Boise
Elected Officials
Citizens Groups
City Council
Planning & Zoning Department
Public Works Department
Honorable John Evans
Governor of Idaho
Honorable Richard Eardley
Mayor, City of Boise
Honorable Jerry Deckard
Mayor, City of Eagle
Honorable Joseph Glaysier
Mayor, City of Meridian
Ada County Conservation League
Ada County Medical Society
Idaho Citizen's Coalition
Idaho Historical Society
Idaho Lung Association
Idaho Water Users Association
Idaho Wildlife Society
League of Women Voters of Boise
League of Women Voters of Idaho
Soil Conservation Society of America
Wilderness Society
Bench Sewer District
Boise Public Library
Eagle Water & Sewer District
The Idaho Statesman
West Boise Sewer District
A local citizen mailing list is available upon request.
258
Others
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BIBLIOGRAPHY
Reference Documents
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ACOG see Ada Council of Governments.
Ada Council of Governments. 1973a. Ada County ecology: a
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. 1973b. Background information for Ada County, Idaho.
Environmental rep. no. 3. Boise. 95 pp.
. 1975a. Land...nature's design for the future: a
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natives. Boise. 56 pp.
. 1975b. Agriculture in Ada County- Boise. 32 pp.
. 1975c. Boise metropolitan area: statistical analysis
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1975d. Boise River water quality monitoring. Environ-
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Ada County Highway District. 1979. Annual budget, 1979-80.
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Ada Data, Inc. 1979. Boise real estate research report of 1979.
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Ada Planning Association. 1978. Demographic and employment
distribution to the year 2000. Boise. 198 pp.
1979a. Southwest wastewater management study, chap-
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Boise. 36 pp.
_, . 1979b. Ada County record subdivision report: summary
points, July 1978 to December 1978. Memorandum from Robert
Hugenberg, Executive Director, and Harvey Gross, Comprehensive
Planning Director.
259
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1980. Southwest community wastewater management
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APA see Ada Planning Association.
Arbib, R. 1979. The blue list for 1980. Am. Birds 33(6) : 830-835.
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Boise Center for Urban Research. 1977. Analysis of alternatives
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Boise Planning and Zoning Department. 1979. Draft environmental
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Boise Project Board of Control. 1979. Annual report, 1978.
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Burt, W. H., and R. P. Grossenheider. 1976. A field guide to
the mammals. 3rd ed. Houghton Mifflin Co., Boston. 289 pp.
Business Economics, Inc. 1976. An analysis of growth management
fees in Ada County, Idaho. Prepared for Ada Planning Association
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Administration. Boise.
Business Economics, .Inc., and Benkendorf and Associates. 1978.
1978 housing study. Prepared for Ada Planning Association.
Caldwell, H. H., and M. Wells. 1974. Economic and ecological
history support study for a case study of federal expenditures
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Carlton, N. K. 1969. A history of the development of the Boise
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Central District Health Dept. 1979. Southwest Boise water study,
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CH2M Hill, Inc. 1977. Urban runoff control handbook for Ada
and Canyon Counties. Prepared for Ada/Canyon Waste Treatment
Management Committee. 46 pp. + tables.
260
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. 1979a. Mechanical treatment alternatives, City of
Boise, Idaho, wastewater facilities plan. Prepared for the
City of Boise. Technical memorandum, Oct. 1979.
. 1979b. Planning and design criteria, City of Boise
wastewater facilities plan. Prepared for the City of Boise.
Technical memorandum, May 1979.
. 1979c. South Boise interceptor extension route
selection, City of Boise wastewater facilities plan. Prepared
for the City of Boise. Technical memorandum, November 1979.
. 1979d. West Boise hydraulic capacity analysis, City
of Boise wastewater facilities plan. Prepared for the City of
Boise. Technical memorandum, September 1979.
. 1979e. Sludge management. Prepared for the City of
Boise. Technical memorandum.
. 1979f. North Boise interceptor. Prepared for,the
City of Boise. Technical memorandum, September 1979.
±!
. 1980a. Boise wastewater facilities plan: summary.
Prepared for the City of Boise.
. 198Ob. Flow augmentation and flow routing. Prepared
for the City of Boise. Technical memorandum.
. 1980c. Wastewater facilities plan, Boise, Idaho,
parts I and II: preliminary draft. Prepared for the City of
Boise.
Costle, Douglas M. 1978. EPA policy to protect environmentally-
significant agricultural lands. Letter from the Administrator,
U.S. Environmental Protection Agency to Assistant Administrators,
Regional Administrators, and Office Directors.
Davis, J. C. 1975. Minimal dissolved oxygen requirements of
aquatic life with emphasis on Canadian species: a review.
J. Fish Res. Board Canada 32:2295-2332.
Davis, J. C., et al. 1979. Dissolved oxygen. Pp.169-174 in
R. V. Thurston, et al., eds., A review of the EPA red book:
quality criteriaTor water. Water Quality Section, American
Fisheries Society, Bethesda, MD.
261
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Dion, M. P. 1972. Some effects of land-use changes on the shallow
groundwater system in the Boise-Nampa area, Idaho. Water info.
bull. no. 26. Idaho Dept. of Water Administration. 47 pp.
Eagle (City). 1980. Statement of revenue for the quarter ended
March 31, 1980.
Eagle Planning and Zoning Commission. 1978. Eagle comprehensive
plan.
Eagle PZC see Eagle Planning and Zoning Commission.
Elrick and Lavidge, Inc. 1980. The Pacific Northwest residential
energy survey, vol. I: executive summary. Bonneville Power
Administration, Portland, OR. 81 pp.
ESL, Inc., and CH2M Hill, Inc. 1974. Ambient air quality measure-
ments in the Boise, Idaho, urban area. Prepared for Idaho
Transportation Dept. and Ada County Highway District.
European Island Fisheries Advisory Commission. 1979. Water
quality criteria for European freshwater fish: report on
ammonia and inland fisheries. EIFAC techn. pap. no. 11. 12 pp.
Gibson, H. R. 1978. Survey of fish populations and water quality
in the Boise River from its mouth upstream to Barber Dam.
Idaho Dept. of Fish and Game Snake River fisheries investiga-
tions job performance report, project no. F-63-R-4. 64 pp.
H. Esmaili & Associates, Inc. 1980a. Groundwater resources of
Boise Valley, Idaho: preliminary draft. Prepared for Jones
& Stokes Associates, Inc.
. 1980. Non-point source waste loadings in Ada
County and southwest community study areas: preliminary draft.
Prepared for Jones & Stokes Associates, Inc.
Henderson, D. M., F. D. Johnson, P. Packard, and R. Steele. 1977.
Endangered and threatened plants of Idaho: a summary of current
knowledge. University of Idaho, College of Forestry;, Wildlife
and Range Science bull. no. 21. 72 pp.
Holmgren, Arther H. 1972. Handbook of the vascular plants of
the northern Wasatch. 4th ed. Intermountain Herbarium, Utah
State University, Logan. 202 pp.
Idaho Air Quality Bureau. 1978. Staff report, Boise carbon
monoxide study, winter 1977 - spring 1978, Boise, Idaho.
Idaho. Dept. of Employment. 1979. Selected Ada County employment
statistics.- Unpublished data from Research and Analysis Bureau,
Boise.
262
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Idaho. Dept. of Fish and Game. 1977. Habitat and species report,
Ada County. Boise. 16 pp.
1978. A plan for the future management of Idaho's
fish and wildlife resources, vol. I: goals, objectives, and
policies, 1975-1990. Boise. 170 pp.
Idaho. Dept. of Fish and Game, and U.S. Bureau of Land Management.
1977. Sensitive species supplement to the master memorandum
of understanding between the Idaho Dept. of Fish and Game and
the U.S. Bureau of Land Management. Boise. 2 pp.
Idaho. Dept. of Health and Welfare. n.d. Rules and regulations
for the control of air pollution in Idaho. Boise.
Idaho. Dept. of Water Resources. 1978. Ada County, Idaho:
water-related land use. Boise.
Idaho. Division of Tourism and Industrial Development. 1977.
Idaho almanac. Boise. 447 pp.
Idaho. Water Resources Board. 1974. Hydrology support study
for a case study of federal expenditures on a water and related
land resource project, Boise project, Idaho and Oregon.
Idaho Water Resources Research Institute, University of Idaho,
Moscow. 157 pp.
Jensen, Scott W. 1980. Wintering bald eagles of the Lower
Boise River. U.S. Fish and Wildlife Service. Unpublished
report. 9 pp.
•Jones & Stokes Associates, Inc. 1980. Draft drainage task report:
drainage planning and institutional evaluations. Prepared
for U.S. Environmental Protection Agency. 51 pp.
J-U-B Engineers, Inc. 1978. Study plan for Eagle water and
sewer plan. Nampa, ID.
. 1980. Draft step 1 wastewater facility plan, Eagle
water and sewer district. Prepared for Eagle Water and Sewer
District. Nampa, ID. 95 pp. + appendices.
J-U-B Engineers, Inc., and Barton, Stoddard, Milhollin & Higgins.
1973. Boise metropolitan area storm sewer system general
plan. Prepared for Ada Council of Governments. Nampa, ID.
48 pp. + appendices.
Kennison, John A. 1980. [Status report of Astragalus mulfordaeT}
Oregon Natural Heritage Program, Portland. 16 pp. Mimeo.
263
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Lewis, G. C., D. V. Naylor, J. R. Busch, and D. W. Fitzsimons.
1978. Groundwater quality study in the Boise Valley.
Idaho Agricultural Experiment Station res. bull. no. 105.
30 pp.
McAffee, W. R. 1966. Rainbow trout. Pp.192-215 in A. Calhoun,
ed., Inland fisheries management. Calif. Dept. of Fish & Game,
Sacramento.
Maid, H. E., and H. A. Powers. 1962. Upper cenozoic stratigraphy
of Western Snake River plain, Idaho. Geol. Soc. Am. Bull. 73:
1197-1220.
Mathematical Sciences Northwest, Inc. 1979. Estimating energy
impacts of residential and commercial building development:
a manual (draft). Prepared for U.S. Dept. of Energy.
Mink, L. L., A. T. Wallace, and M. G. Lucky. 1975. Study on
the impact of subsurface sewage disposal in the Ada/Canyon
County area of southwest Idaho. U.S. Army Corps of Engineers
regional water management study. 61 pp.
Mohler, Levi L. 1974. Threatened wildlife of Idaho. Idaho
Wildl. Rev. 26(5):3-5.
Moyle, P- B. 1976. Inland fishes of California. University of
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Nace, R. L., S. W. West, and R. W. Mower. 1957. Feasibility
of groundwater features of the alternate plan for the Mountain
Home project, Idaho. U.S. Geological Survey Water Supply Pap.
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National Fish and Wildlife Laboratory. 1980. Selected vertebrate
endangered species of the seacoast of the United States. U.S.
Fish & Wildlife Service. FWS/OBS-80/01.
Packard, Patricia L. 1979. Status report Allium aaseae. College
of Idaho, Biology Dept., Caldwell, ID. 12 pp. Mimeo.
Peterson, R. T. 1961. A field guide to western birds. 2nd ed.
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Council on Environmental Quality, Washington, D.C. Memorandum.
Pruitt, T. A., and R. L. Nadeau. 1978. Recommended stream re-
source maintenance flows on seven southern Idaho streams.
Instrecn Flow Info. Pap. No. 8. U.S. Fish and Wildlife Service,
Ft. Collins, CO.
264
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Snow, Carol. 1972. American peregrine falcon (Falco peregrinus
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U.S. Bureau of Land Management Techn. Note. 35 pp.
. 1973. Southern bald eagle (Haliaeetus leucocephalus
leucocephalus) and northern bald eagle (Haliaeetus leucocephalus
alascanus). HaM^at management series for endangered species
rep. no. 5. U.S. Bureau of Land Management Techn. Mote. 58 pp.
. 1974a. Spotted bat (Euderma maculatum) . Habitat
management series for endangered species rep. no. 4. U.S.
Bureau of Land Management Techn. Note T-N-170. 13 pp.
. 1974b. Prairie falcon (Falco mexicanus). Habitat
management series for unique or endangered species rep. no. 8.
U.S. Bureau of Land Management Techn. Note T-N-240. I8 pp.
. 1974c. Ferruginous hawk (Buteo regalis) . Habitat
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U.S. Bureau of Land Management Techn. Note T-N-255. 23 pp.
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amphibians. Houghton Mifflin Co., Boston. 279 pp.
U.S. Bureau of Land Management. 1980. Snake River birds of
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U.S. Bureau of Reclamation. 1979. Boise Valley shallow ground-
water study, first year review- 27 pp.
U.S. Bureau of the Census. 1977. 1974 census of agriculture.
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U.S. Council on Environmental Quality- 1976. Untaxing open
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U.S. Dept. of Labor. 1979. Employment and earnings, 1909-1978.
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265
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1971b. Noise from construction equipment and
operations, building equipment and home appliances. Prepared
by Bolt, Beranek and Newman.
1976. Quality criteria for water. U.S. Environ-
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1977a. Municipal sludge management: environmental
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. 1977b. Draft background paper on EPA programs and
environmentally-significant agricultural lands. Washington,
D.C. Memorandum from Office of Land Use Coordination,
December 5, 1977.
. 1978a. Municipal wastewater treatment works con-
struction grantE program, state and local assistance, grants
for construction of treatment works (Title 40, pt. 35, subpart
E) . Fed. Reg. 44022-22099 (Sept. 27, 1978).
. 1978b. Carbon monoxide study, Boise, Idaho, Nov.
25-Dec. 22, 1977, parts 1 and 2. Prepared by C. B. Wilson
and J. W. Schweiss.
. 1978c. Idaho environmental quality profile, 1978.
U.S. Fish c.nd Wildlife Service. 1973. Threatened wildlife of
the United States. Washington, D.C. 289 pp.
1980. List of endangered and threatened wildlife
and plants. 45 Fed. Reg. 33768 (May 20, 1980), as amended
through July 14, 1980.
U.S. Soil Conservation Service. 1979. Soil survey of the Ada
County area, Idaho. Boise. 327 pp. + maps.
v-Jebb, D. 1958. Bioassay report, Boise River. Idaho Dept. of
Fish and Game, Boise. File report.
Wilbur Smith and Associates, Inc. 1976. Demographic and economic
base study, Ada County, Idaho.
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266
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Zarn, Mark. 1974a. Burrowing owl (Speotyto cunicularia hypugaea).
Habitat management series for unique or endangered species
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25 pp.
1974b. Osprey (Pandion haliaetus carolinensis).
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254. 41 pp.
Personal Communications
Barker, L. S. December 18, 1979. CH2M Hill, Boise. Letter to
C. .R. Mickelson, Boise City Engineer.
April-May 1980. CH2M Hill, Boise. Telephone conversa-
tions.
Berent, Mary- August 20, 1979. Data Technician, Ada Planning
Association, Boise. Memorandum on Ada County recorded subdi-
vision report and summary points.
Blake, Diane. May 1930. Ada Planning Association, Boise. Tele-
phone conversation.
Boise Water Corporation. 1980. Well log and well-water quality
data. Written and verbal unpublished data.
Boros, John. May 29, 1980. District Chief, Boise Fire Dept.
Telephone conversation.
Federal Emergency Management Agency. January 1981. Telephone
conversation with map identification facility, Bethesda, MD.
Fintel, Robert. January 1981. U.S. Army Corps of Engineers,
Walla Walla, WA. Telephone conversation.
Howard, Rich. October 7, 1980. Threatened and Endangered Species
Office, U.S. Fish and Wildlife Service, Boise. Telephone
conversation.
Johnson, Margaret. May 1980. Planner, Ada Planning Association.
Telephone conversation.
Keating, James. March 1980. Idaho Dept. of Fish and Game, Boise.
Telephone conversation.
. July 14, 1980. Letter to Jones & Stokes Associates,
Inc.
267
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Kelley, Fenton. April 23, 1980. Professor of Ichthyology, Boise
State University. Telephone conversation.
Leach, C. 1980. Idaho Dept. of Water Resources. Telephone
conversation.
McKinney, ?. May 29, 1980. Vice-President of Marketing, Inter-
mountain Gas Company. Telephone conversation.
Merhoff, L. A. July 23, 1980. Area Manager, U.S. Fish and Wild-
life Service, Boise. Letter to Jones & Stokes Associates.
Minter, Bob. August 9, 1979. Environmental Planning Director,
Ada Planning Association. Memorandum on urban storm drainage
summary report.
January 1981. Telephone conversation.
Murrey, A. E. 1980. Idaho Dept. of Health and Welfare, Boise.
Letter to Bill Ancell, Public Works Superintendent, City of
Boise.
Nadeau, Richard L. May 2, 1980. Fishery Biologist, U.S. Fish and
Wildlife Service, Washington, D.C. Telephone conversation.
Neal, Dave. August 29, 1979. Ada County Environmental Office.
Telephone conversation.
Parker, Tom. October 1, 1980. Wildlife Biologist, Idaho Dept. of
Fish and Game, Boise. Telephone conversation.
Reid, Will. March 20, 1980. Fishery Biologist, Idaho Dept. of
Fish and Game, Boise. Telephone conversation.
. April 1980. Telephone conversation.
Stacy, Susan. May 1980. Boise Planning Dept. Telephone conversa-
tion .
Steele, Robert. October 1980. U.S. Forest Service Intermountain
Forest and Range Experiment Station, Boise. Telephone conversa-
tion.
Vickers, Kirby. 1981. Engineer, J-U-B Engineers, ITampa, ID.
Telephone conversation.
268
• GPO 797-370 l»«
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