Wastewater Management Plan for the Durango Area, La Plata County, Colorado

United States Regions EPA 309/o-8S-0018
Environmental Protection 18^0 l.iaco'n Street Jcr.uc.ry, I98!
Agency Denver, Colorado 30236
dEPA Environmental appendix
impact
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ENVIRONMENTAL IMPACT STATEMENT
WASTEWATER MANAGEMENT PLAN FOR THE
DURANGO AREA, LA PLATA COUNTY, COLORADO
APPENDICES
Prepared for
U.S. Environmental Protection Agency
Region VIII
1860 Lincoln Street
Denver, Colorado 80295
December 1980
By
ENGINEERING-SCIENCE
2785 North Speer Boulevard
Denver, Colorado 80211
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TABLE OF CONTENTS
PaSe
FIGURES
TABLES
APPENDIX A ENVIRONMENTAL SETTING, DURANGO, COLORADO A-l
The Setting A-2
Topographic Features A-3
Geology A-A
Soils A-8
Animas River Valley A-8
Florida River Valley A-21
The Florida Mesa A-25
Lightner Creek A-28
Junction Creek A-31
Flood Plain A-32
Vegetation A-33
Wildlife A-63
Aquatic Life A-70
Fish A-70
Aquatic Invertebrates A-77
Threatened and Endangered Species A-78
Surface Water Quality A-80
Water Quality Standards A-80
Animas River A-89
Lightner Creek A-101
Hermosa Creek A-104
Junction Creek A-104
Florida River A-10A
Dischargers A-108
Groundwater Quality A-113
Data Sources A-113
Groundwater Data Evaluation A-116
Lightner and Junction Creek Areas A-123
Florida River Area A-12A
Florida Mesa Area A-125
Supplemental Water Quality Monitoring Program A-127
Surface Water Monitoring A-129
Groundwater and Spring Water Monitoring A-132
Conclusions A-135
i
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TABLE OF CONTENTS Continued)
Page
Population, Socioeconomic Factors,
Land Use A-137
Existing Conditions A-137
Recent Growth Trends A-137
Sources of Past Growth A-138
Tourism A-139
Part-time residents A-141
In-migrants A-142
Growth and the Housing Supply A-142
Future Growth A-143
Influences of Future Growth A-143
Tourism A-143
Energy resources development A-144
Agriculture A-145
Factors discouraging growth A-146
Growth Projections A-147
Accuracy of Projections A-150
Area 1: Hermosa A-154
Current Level of Development A-155
Influences on Future Development A-156
Physical constraints A-156
Land ownership A-157
Land use planning A-157
Proposed major developments A-157
Infrastructure A-158
Local attitudes A-159
Summary A-159
Area 2: Junction Creek A-160
Current Level of Development A-160
Influences on Future Development A-160
Physical constraints A-160
Land ownership A-161
Land use planning A-161
Proposed major developments A-161
Infrastructure A-162
Local attitudes A-163
Summary A-163
Area 3: Lightnex Creek and Durango West A-163
Current Level of Development A-164
Influences on Future Development A-164
Physical constraints A-165
Land ownership A-166
Land use planning A-166
Proposed major developments A-166
Infrastructure A-166
Local attitudes A-167
Summary A-167
ii
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TABLE OF CONTENTS (continued)
Pa8e
Area 4: Grandview-Loma Linda A-167
Current Level of Development A-167
Influences on Future Development A-169
Physical constraints A-169
Land ownership A-169
Land use planning A-169
Proposed major developments A-169
Infrastructure A-170
Local attitudes A-170
Summary A—170
Area 5: Florida Road A-171
Current Level of Development A-171
Influences on Future Development A-172
Physical constraints A-172
Land ownership A-173
Land use planning A-173
Proposed major developments A-173
Infrastructure A-173
Local attitudes A-174
Summary A-174
Area 6: West Animas A—174
Current Level of Development A-174
Influences on Future Development A-175
Physical constraints A-175
Land ownership A-175
Land use planning A-175
Proposed major developments A-175
Infrastructure A-176
Local attitudes A-176
Summary A-176
Summary of Study Area Development and
Development Conditions A-176
Other Potential Sites for Development A-178
Unincorporated Private Lands Near the
City of Durango A-178
Areas North of Hermosa A-179
Meterology and Air Quality A-180
Heterology A-180
Air Quality A-181
REFERENCES A-184
APPENDIX B ENVIRONMENTAL IMPACTS B-l
Topography B-2
Project Impacts B~2
Mitigation Measures B-2
Geology B-2
Project Impacts B-2
iii
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TABLE OF CONTENTS (continued)
Page
Mitigation Measures B-3
Soils B-3
Project Impacts B-3
Mitigation Measures B-A
Water Resources - Surface Water Hydrology B-4
Project Impacts B-4
Mitigation Measures B-6
Water Resources - Surface Water Quality B-8
Project Impacts B-8
Mitigation Measures B-8
Water Resources - Ground Water Quality B-8
Project Impacts B-8
Mitigation Measures B-10
Biological Resources - Vegetation B-10
Project Impacts B-10
Mitigation Measures B-ll
Biological Resources - Wildlife and Special
Status Species B-ll
Project Impact B-ll
Mitigation Measures B-13
Biological Resources - Aquatic Life B-13
Project Impacts B-13
Mitigation Measures B-14
Meterology and Air Quality B-15
Project Impacts B-15
Mitigation Measures B-15
Energy Resources B-15
Project Impacts B-15
Mitigation Measures B-16
Transportation B-16
Project Impacts B-16
Mitigation Measures B-16
Land Use and Population Considerations B-17
Project Impacts B-17
Mitigation Measures B-18
Socioeconomic Considerations B-18
Project Impacts B-18
Mitigation Measures B-19
Cultural Resources B-19
Project Impacts B-19
Mitigation Measures B-20
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LIST OF FIGURES
Page
A - 1 Areas Potentially Constrained for
Development by Geologic Hazards -
Hermosa Study Area A-10
2 Areas Potentially Constrained for
Development by Geologic Hazards -
Junction Creek Study Area A-ll
3 Areas Potentially Constrained for
Development by Geologic Hazards -
- Lightner Creek/Durango West Study Area A-12
4 Areas Potentially Constrained for
Development by Geologic Hazards -
Grandview/Loma Linda Study Area A-13
5 Areas Potentially Constrained for
Development by Geologic Hazards -
Florida Road Study Area A-14
6 Areas Potentially Constrained for
Development by Geologic Hazards -
West Animas Study Area A-15
7 Historic Water Quality Sampling Points A-90
8 Point Source Dischargers in the Study Area A-109
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LIST OF TABLES
Page
A - 1 Soil Limitations and Development
Capabilities A-16
2 Plants of the Study Area A-35
3 Wildlife Species of the Study Area A-64
4 Fish Inventory Based on Electro-Fishing A-71
5 Macro-Invertebrates of Selected Streams A-73
6 Colorado Water Quality Criteria A-81
7 Water Quality Data - Animas River A-91
8 Water Quality Data - Lightner Creek A-102
9 Water Quality Data - Hermosa Creek A-105
10 Water Quality Data - Florida Creek A-107
11 Animas River Drainage Point Source
Discharge Inventory A-110
12 Junction Creek Trailer Park
Discharge Data A-114
13 Standards for Domestic Groundwater Supply A-115
14 Study Area Well Information A-117
15 Groundwater Quality Data A-118
16 Field Monitored Parameters Surface Water
Quality A-130
17 Results of Chemical and Bacterial Analyses
on Surface Waters of the Animas and
Florida Rivers A-131
18 Results of Chemical and Bacterial Analyses
on Groundwater and Spring Water Grab
Samples A-134
vi
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LIST OF TABLES (continued)
Page
19 Recent Population Growth in La Plata
County and Durango A-138
20 Recent Population Growth in the State of
Colorado Planning and Management
Region 9 A-139
21 Representative Visitor Statistics A-141
22 La Plata County Population Projections -
Year 2000 A-148
23 Comparative Sample Land Prices in the 201/
EIS Study Area A-153
24 Recent Residential Construction in Hermosa
Study Area A-156
25 Proposed Major Developments; Hermosa Study
Area A-158
26 Major Developments in the Junction Creek
Study Area A-162
27 Building Permits Issued in Lightner Creek-
Durango West Study Area, 1977-1980 A-165
28 Recent Residential Construction in Grandview
Loma Linda Study Area A-168
29 Recent Residential Construction in Florida
Area A-172
30 Summary of Existing Development and Develop-
ment Conditions, Durango 201 Study Areas A-177
31 Air Quality Data for Durango A-183
vii
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APPENDIX A
ENVIRONMENTAL SETTING
DURANGO, COLORADO
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APPENDIX A
ENVIRONMENTAL SETTING
DURANGO, COLORADO
This appendix presents the existing environmental data base which
was used to evaluate the impacts of the alternatives developed for the
201 Facilities Plan. The focus of the appendix is on the following
environmental features of the Study Area: geology, soils, flood plains,
vegetation, wildlife, and groundwater and surface water quality.
To compile this data base, a wide variety of data sources were
contacted. The data from the various sources are of variable complete-
ness, ranging from broad, general information to very point specific
information. Occasionally, data provided by the same source presented
conflicts in terms of completeness, unity, or analysis. However, the
assembled data base does provide adequate information to identify key
environmental units for the analysis of wastewater management alter-
natives. The following key units have been Identified:
o Geologic features
Depth to bedrock
Geologic hazards
o Soils
Permeability
Depth to groundwater
Development suitability
Septic tank/leach field suitabilities
o Designated flood plains
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o Vegetation/wildlife/aquatic life
Critical big game habitat
Threatened/endangered species habitat
Fisheries
o Water quality
Potential groundwater quality problems
Potential surface water quality problems
These various environmental features of the Study Area were used in the
development of the EIS.
During the review and analysis of the existing water quality data
(surface and ground) it became apparent that the data were inconsistent,
dated, and insufficient to determine current water quality problems in
the Study Area. Furthermore, it was not possible to determine if pre-
viously identified water quality problems still existed, or if new
problems had developed which were not documented. To provide general,
up-to-date baseline information a water quality monitoring program was
implemented. The results of this monitoring program are presented
herein.
THE SETTING
The Study Area is located in southwestern Colorado on the Animas
River. This drainage is tributary to the San Juan River of the Colorado
River complex. The area is bordered by the San Juan Mountains to the
north and west, and by plateaus and mesas to the south and east. The
region is rich in cultural resources and is a popular recreational area
for skiers, bikers, campers, and sightseers. Durango is the major pop-
ulation center in the Study Area; trade and tourism are its predominant
businesses.
Various Indian groups inhabited the area from early history, leav-
ing evidence of their presence in the Mesa Verde cliff dwellings south-
west of the Study Area. Hispanic and Caucasian settlement occurred with
the growth and expansion of railroads, trade, and mining in the mid-
1800' s. During the first half of the 20th century agriculture provided
a marginal to stable living for residents but the various cultural
groups retained a degree of separation. During the 1950's discoveries
A-2
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of energy and mineral resources expanded the population, but agriculture
provided the underlying stability to the economy. During this period
Durango prospered from increases in tourism, recreation related service
industries, retail sales, and real estate expansion. Population in-
creases have continued into the 1970's because of a westward movement of
the nation's population and the increasing popularity of the southwest.
TOPOGRAPHIC FEATURES
Elevations in the Study Area range from about 6,400 feet
to about 8,800 feet. area situated in a transitional area
of the Southern Rocky Mountain Physiographic Province and the Colorado
Plateau Province. The Rocky Mountain Province is characterized by high
peaks, great relief, and ruggedness. Rocks are of igneous, metamorphic,
and sedimentary origin, and soils are usually shallow. It is a scenic
area of intermixed bare rock and forest, with valuable water and mineral
resources. The Colorado Plateau Province, Navajo Section, consists of
extensive areas of nearly horizontal sedimentary formations, structural
upwarps, igneous structures, and steep walled canyons. It is an arid
area of bare rock, sparse vegetation, and highly varied desert scenery.
Principal topographic features Include the San Juan Mountains out-
side the Study Area to the north, Animas City Mountain northwest of
Durango, Florida Mesa southeast of Durango, and the Animas River and its
tributaries.
The Animas River headwaters are located in the San Juan Mountains
north of the Study Area. The main stem Animas flows through a narrow
canyon with steep slopes and sheer rock walls. The stream gradient is
about 90 feet per mile (1.7 percent) and the stream is shallow. The
Animas River flows into the Animas Valley at Baker's Bridge, where an
abrupt change in gradient occurs. The gradient decreases to about 20
feet per mile (0.4 percent), and is a consequence of the glacial action
which formed the valley. The meandering feature of the river is evi-
denced by the existence of several oxbow lakes which have formed in old
stream channels. A terminal moraine exists at the north edge of Durango.
Downstream of Durango, the valley is broad and the river has few
meanders. The stream gradient is about 26 feet per mile (0.5 percent).
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Hermosa Creek is a steep, swiftly flowing mountain stream through-
out most of its length. Near its mouth it meanders into the Animas
Valley in a broader channel. Junction Creek is also a swiftly flowing
stream with well-defined channels. Dry Gulch Creek, a tributary of
Junction Creek, has similar features. Dry Gulch Creek joins Junction
Creek about one-half mile upstream from the confluence of Junction Creek
with the Animas River. The Lightner Creek drainage lies to the south of
the Junction-Dry Gulch Creek drainage and has similar features.
GEOLOGY
Within the Study Area there are nineteen geologic formations and
eleven surficial deposits. Geologic features can be separated into two
general groups along an east-west line north of the City of Durango.
Formations north of this line form the basal structure of the southern
edge of the San Juan Mountains; south of this line the geology has
formed mesas and plateaus. Geologic formations north of the separation
line range in age from the Upper Cretaceous to Precambian, while forma-
tions south range from Quaternary to Upper Cretaceous. Quaternary
alluvium is common in most stream beds.
The geologic formations in the Study Area include:
o alluvial deposits (Quaternary)
o landslip debris (Quaternary)
o glacial drift (Quaternary)
o Animas Formation, McDermott member (Upper Cretaceous)
o San Jose, Nacimiento, and Animas Formations (Eocene, Paleocene,
Upper Cretaceous)
o Kirkland Shale, Upper Shale Member (Upper Cretaceous)
o Kirkland Shale, Farmington Sandstone Member (Upper Cretaceous)
o Lewis Shale (Upper Cretaceous)
o Cliff House Sandstone (Upper Cretaceous)
o Point Lookout Sandstone (Upper Cretaceous)
o Mancos Shale (Upper Cretaceous)
o Dakota Sandstone and Burro Canyon Formation (Upper and Lower
Cretaceous)
o Morrison Formation (Upper Jurassic)
o Entrada Sandstone (Upper Jurassic)
A-A
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o Dolores Formation (Upper Triassic)
o Cutler Formation (Lower Permian)
o Rico, Hermosa, and Molas Formations (Lower Permain and
Pennsylvanian)
Alluvial deposits consist of alluvium, terrace gravels, and allu-
vial fan deposits. The materials associated with the alluvium include
silt, sand, and gravel associated with modern flood plains. Terrace
gravels are old stream deposits lying on surfaces above the present
flood plain. Alluvial fan deposits are sand, gravel, and wash deposits
set down in a fan-shaped wedge at the mouths of tributaries. In the
Animas River valley north of Durango the majority of the existing devel-
opment has occurred on the alluvial deposits. Alluvial deposits are
also found in the bottomlands of Junction Creek, Lightner Creek and the
Florida River.
Northeast of Durango, in the Animas Valley, glacial till deposits
can be found. These deposits are poorly sorted silt- to gravel-sized
material deposited by glacial ice, primarily as terminal or lateral
moraines.
The oldest formation in the Study Area is found at Baker's Bridge.
This formation, Baker's Bridge Granite, is a pale-red, massive, medium
to coarse-grained granite. It contains abundant perthite, plagioclose,
and complexly altered hornblende and biotite. This is a rock outcrop
with no surficial deposits associated with it.
Ascending out of the Animas Valley in the area north of Trimble,
the geologic formations include Rico, Hermosa, and Molas Formations.
The Rico Formation consists of nonmarine red beds of shale, siltstone,
arkosic sandstone, and grit; it represents transitional beds between the
Cutler and Hermosa Formations, and throughout much of the area is not
recognizable as a distinct unit. The Hermosa Formation is largely
dark-gray marine shale, siltstone, mudstone, and arkosic grit. Molas
Formation is mostly nonmarine shale, siltstone, sandstone, conglomerate,
and basal red breccia. Surficial deposits on these formations include
areas of landslide deposits (jumbled masses of earth material derived
from slope failure), and complex slope failure deposits (similar to
landslide deposits, but include large areas of multiple slope failures).
A- 5
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The interface between the geologic formations and the alluvial valley
consists of surficial deposits of colluvial wedges. These wedges con-
sist of gravity—transported debris which occur as, a lenticular wedge.
In the Study Area north of Trimble development has been limited on these
formations.
Above the Rico, Hermosa, and Molas Formations is the Cutler Forma-
tion. This is predominantly a nonmarine red shale, siltstone, sand-
stone, and limestone-pebble conglomerate. North of Durango this forma-
tion is located on the east and west side of the Animas Valley from
Trimble south to Animas City Mountain. Surficial deposits at the Cutler-
alluvium interface are the colluvial wedge deposits. Development has
been primarily on the west side of the Animas Valley at the base of the
Cutler Formation. Falls Creek cascades over the Cutler formation into
the Valley.
South toward Animas City Mountain and the northern side of Junction
Creek drainage, geologic complexities increase. Two formations, the
Morrison and Dakota Sandstone-Burro Canyon, are found. The Morrison
Formation is mostly vari-colored claystone and mudstone. The Dakota
Sandstone disconformably overlies the Burro Canyon Formation. The
Dakota Sandstone is a light-gray to brown sandstone with interbedded
siltstone and carbonaceous shale. It commonly contains chert pebble
conglomerate sandstone at the base, while the Burro Canyon is a len-
ticular chert-pebble conglomerate interlayed with green and gray clay-
stone. Also occurring in the area is a thin band of Entrada Sandstone.
This formation is a light-gray crossbedded sandstone. Surficial dep-
osits associated with these formations include landslide deposits and
complex slope failure deposits. Development has been limited on these
formations to very scattered home sites with the greatest density in the
Florida River drainage.
The east-west transitional area between the mountains and mesa
lands consists of about six different geologic formations. They create
the land forms from the southern drainage of Junction Creek and the
Lightner Creek drainage on the west to the narrow ridges east of Durango
to the Florida River. The formations include Mancos Shale, Point Look-
out Sandstone, Cliff House Sandstone, Lewis Shale, and Kirkland Shale
(Farmington Sandstone and Upper Shale Members).
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The Mancos Shale is a dark-gray marine shale. The Point Lookout
Sandstone is a light-gray to yellowish-gray sandstone with interbedded
siltstone and shale in its lower part. Gray calcareous sandstone,
argillaceous sandstone, mudstone and silty shale form the Cliff House
Sandstone formation. The Lewis Shale is dark-gray clay shale containing
thin sandstone beds near the top and rusty-weathering concentrations in
the lower part. The Upper Shale Member of the Kirkland Formation is
sandy shale and light-gray sandstone; the Farmington Sandstone is light-
gray sandstone, with beds of greenish-gray shale. Development on these
formations is very limited. Surficial deposits associated with these
formations include landslide deposits, pediment gravels (sand and gravel
deposits of glacial outwash often blanketed by loess; usually found at
higher levels or as "caps" on mesas), glacial till deposits, and
alluvial-colluvial deposits (a mixture of alluvial deposits and gravity
derived slope wash deposits).
The remaining geologic formations in the Study Area have formed the
Florida Mesa and the lower segments of the Florida and Animas Rivers.
The northern area of Florida Mesa is the Animas Formation; most of the
remaining areas are alluvial deposits from the Animas and Florida
Rivers. Along the edges of the alluvium, and in intermittent drainages
off of the Mesa, the San Jose, Nacimiento and Animas Formations occur.
The Animas Formation is a dark vari-colored sandstone, shale, and con-
glomerate which contains abundant volcanis and arkosic detritus. Sur-
ficial deposits associated with the Animas Formation include alluvial
colluvial deposits and some alluvial deposits. The alluvial formations
of the Mesa have surficial deposits of pediment gravels with some
colluvial deposits on the western edges.
Faults in the area are confined to the southeast area of Durango,
and tend to run from the southwest to the northeast. La Platta County is
in seismic zone two and is subject to moderate earthquake damage. Other
identified geologic hazards include rock falls, debris fans (areas sub-
ject to wash from tributary streams), unstable and potentially unstable
slopes, areas of high and moderate erosion potential, landslide areas,
and slope failure complexes. These hazardous conditions have been
responsible for preventing development of some otherwise desirable sites
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within the Study Area. Specific geologic hazard constraints for each
area are presented in Figures I through 6.
The geologic features described above have been mapped and are
available from U.S. Geological Survey and Colorado State Geological
Survey, (References 1,2). These features are identified for the purpose
of locating areas that might present special problems to certain types
of development or use. Such areas should be evaluated on a more site
specific basis.
SOILS
Soils information for the Study Area is available from the U.S.
Soil Conservation Service (SCS) in preliminary form, (Reference 3). For
evaluating soil suitabilities the Study Area is divided into the
following subareas: Animas Valley north of Durango, Junction Creek,
Lightner Creek, Florida Mesa and Florida River Valley. Within these
areas only those soils currently or potentially facing development are
discussed. The suitabilities of the soils in terms of septic tank
absorption fields, groundwater table, flooding potential, slope, and
shrink-swell characteristics are listed by subarea in Table 1.
Animas River Valley
Detailed soils information in the Animas Valley north of Trimble is
currently not available; however, general soils associations are mapped.
The Animas River Valley consists of loam soil and river wash flanked by
rubble and rock outcrops. Loam makes up approximately sixty percent of
the area, riverwash makes up approximately thirty percent of the area,
and rubble and rock outcrop make up approximately ten percent of the
area. The principal limiting features of soil in the Animas River
Valley for development and the use of septic tank absorption fields are
flood potential, shallow groundwater, and depth to bedrock. Specific
soils of the valley are Werlow loam, Connerton loam, Humbarger loam,
Fescar fine sandy loam, and Garza loam.
The predominant soil on the flood plain is the Werlow loam, a deep,
somewhat poorly drained soil which formed in mixed alluvium. Typically,
the surface layer is a pinkish-gray loam about five inches thick. The
lower part of the surface horizon is typically a pale brown loam about
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GEOLOGIC
A - SNOW AVALANCHE Areas sub-
ject to snow avalanches; arrows
refer to direction of run.
S ¦ SUBSIDENCE Areas of known or
potential ground subsidence.
RF " ROCK FALL Areas below very
steep slopes or cliffs subject to
periodic rockfall.
F = FAULT Known fractures where
displacement is recognized; La
Plata County is in seismic zone
two and is subject to
moderate damage.**
DF - DEBRIS FAN Areas subject to
torrential wash from tributary
streams.
PUS = POTENTIALLY UNSTABLE
SLOPES Slopes in equilibrium
but subject to failure if
disturbed improperly.
US - UNSTABLE SLOPES Slopes sub-
ject to failure (such as creep)
but not known to be
landslides.
HAZARDS KEY*
SFC ¦ SLOPE FAILURE COMPLEX
Known areas of complex slope
failure often associated with
multiple landslides; arrows refer
to direction of movement.
LS - LANDSLIDE Known areas of
slope failure including rotational
and translational slides, debris
slides and rock avalanches;
arrows refer to direction of
movement.
MF *= MUD FLOW Known areas of mud-
flows, debris flows and earth
flows.
RT - RADIOACTIVE TAILINGS Known
areas of mill tailings which are
radioactive.
GEOLOGIC CONTRAINTS
HEP = HIGH EROSION POTENTIAL
Areas subject to a high rate of
soil erosion; requires care in land-
use planning.
MEP - MODERATE EROSION POTENTIAL
Areas subject to a moderate rate
of soil erosion; requires care in
land-use planning.
*For general information concerning
geologic hazards see "Rogers, W.P., and
others, 1974, Guidelines and criteria
for identification and land-use controls
of geologic hazard and mineral resource
areas" Colorado Geological Survey,
Special Pub. No. 6, 146 p.
**Seismic risk classification recommended
by Colorado State Geological Survey.
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FIGURE 1
AREAS POTENTIALLY CONSTRAINED FOR
DEVELOPMENT BY GEOLOGIC HAZARDS
- HERMOSA STUDY AREA
r —
—i
25
MILES
DF
34
35
DF
.PUS
DF
MF
PUS
US
PUS
DF
PUS,
DF
-
ENGINEERING-SCIENCE
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FIGURE 2
AREAS POTENTIALLY CONSTRAINED FOR
DEVELOPMENT BY GEOLOGIC HAZARDS
- JUNCTION CREEK STUDY AREA
0 12
MILES
ENGINEERING-SCIENCE
-------
AREAS POTENTIALLY CONSTRAINED FOR
DEVELOPMENT BY GEOLOGIC HAZARDS
- LIGHTNER CREEK/DURANGO WEST STUDY AREA
16
lRF| l'1"
I
!<
Ls
\ 14

I \_ -J

\\ /\
24
RF
27
25
MILES
-------
AREAS POTENTIALLY CONSTRAINED FOR
DEVELOPMENT BY GEOLOGIC HAZARDS
- GRANDVIEW/LOMA LINDA STUDY AREA
MILES
*1
M
-------
AREAS POTENTIALLY CONSTRAINED FOR
DEVELOPMENT BY GEOLOGIC HAZARDS
- FLORIDA ROAD STUDY AREA
/

\
MILES
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FIGURE 6
AREAS POTENTIALLY CONSTRAINED FOR
DEVELOPMENT BY GEOLOGIC HAZARDS
- WEST ANIMAS STUDY AREA
MILES
ENGINEERING-SCIENCE
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TABLE I
SOIL LIMITATIONS ANO DEVELOPMENT CAPABILITIES

High

Floods
Hater
Excessive
Slou Shallow
Excess 1ve
Soil

Occur
Table
S lope
Peraeablllty Bedrock
Shrlnk-S»el1
An lass River
Merlon Loaa
P
P

Vallay
Cannertoa Loaa

F
M

Huabarger Loaa

(Includes Her-
Pascar Loaa
P
P

¦oh 1 Hest
Carta Loaa

P
M

Anises Areas)
Fluvaquent
P
P

Rlveruash
P
P

Haploborolls Rubble

Fortutagate-Rock

P
P

Garza-Claybura Rock

Goldvale~Fortulngate

P
P
P

Valto Rock

Ulata-Leadvl1le-AnvIk

Florida River
Hesperus Loaa

Valley
Her low Loaa
P
P

Pescer Loaa
P
P

(Includes
Ploae Loaa

F
Florida Road
Goldvale Loaa

P
F
M
Aree 1
Nordic Loaa

Alaaoaa Loaa

Claybura Loaa

F
F

Flwvaquant
P
P

Carracas-Sanchei

P
M P

Outcrop

Valto Rock

Fortwlegate-Rock

P
P

Florida Mesa
Falfa Loaa

F
F
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High
Floods Water Excasslva Slow Shallow Excasslva
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-------
15 inches thick. The underlying material is a pinkish-gray loam strati-
fied with loamy fine sand and fine sandy loam to 40 inches or more. Sand
and gravel may underlie this soil at any depth below 40 inches. Werlow
loam is used for agricultural land, pastureland, and rangeland. In
addition, the soil has fair to good potential for supporting rangeland
and openland wildlife. Permeability of Werlow loam is moderate to
moderately rapid. Surface runoff is slow, and the erosion hazard is
moderate. The available water capacity of the soil is high, and the
water table in most places fluctuates between two to three feet from the
surface during the spring and summer. The soil is subject to occasional
flooding.
Connerton loam has a good potential for use as homesites and other
developments. Expansion of the Durango area has resulted in urbanization
of this soil. Slope and the rapid permeability rate are its primary
limiting features. Foundations and sanitary facilities can and should
be designed to overcome these limitations.
Humbarger loam, found on both alluvial fans and flood plains of
major drainages, is a deep and moderately well-drained soil. It formed
in moderately fine-textured alluvium. The surface layer is gray loam
about 14 inches thick. The underlying material is dark grayish-brown
loam to a depth of 60 inches or more. Humbarger loam is used mainly for
irrigated crops, pasture, and range. Permeability is moderately slow to
moderate. Available water capacity is high, and surface runoff is slow.
Erosion hazard for this soil is slight. In general, Humbarger loam has
poor potential for use as homesites and other developments. The main
limitation of the soil is its spring season high water table. Construc-
tion of septic tanks and absorption fields might tend to jeopardize
groundwater quality.
Also found on flood plains and terraces is the Pescar fine sandy
loam. This deep, somewhat poorly drained soil formed in stratified
calcareous mixed alluvium. Generally, the surface layer is light
brownish-gray fine sandy loam about eight inches thick; the underlying
layer is a light brownish-gray fine sandy loam about 12 inches thick.
The substream is light brownish-gray very gravelly sand that extends to
a depth of 60 inches or more. Pescar soil is used mainly for irrigated
A-18
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pasture and hayland and the soil is well suited for wildlife. Permea-
bility of the Pescar fine sandy loam is moderate to rapid. Surface
runoff is very slow and thus the erosion hazard is flight. Unlike other
soils discussed, available water capacity is low. This soil has a
fluctuating water table which is within 18 to 30 inches of the surface
during the spring and summer, and is subject to frequent flooding from
April through September. In general, the frequent flooding, seepage,
and depth of the water table during spring and summer limit use of this
soil for homesites and other urban developments. In order to overcome
these limitations, intensive and costly engineering design and special
measures may be required.
Garza loam is situated on mountain slopes and is generally a deep
well-drained soil. It formed in alluvial and colluvial material. The
upper part of the surface layer is grayish-brown loam about 20 inches
thick. The underlying material is light brownish-gray cobbly loam that
extends to 60 inches or more. This soil is used mainly for woodland,
native pasture, and homesite development. Permeability of Garza loam is
moderate and available water capacity is high. Surface runoff is mod-
erate; thus, erosion hazard is light. The soil is suitable for home-
sites and other developments, unless the slope becomes a limiting
factor. Compensating engineering designs and measures are required to
minimize slope limitations when constructing roads and dwellings.
Sealing methods are also required on Garza loam when constructing sewage
lagoons to overcome the threat of seepage.
Intermingled with the loam soils in the flood plains are Fluvaquent
soils and Riverwash. Both are somewhat poorly drained soils which have
a high water table throughout the year and are prone to flooding. The
Fluvaquent soils generally consist of gravelly or cobbly loam overlying
sand and gravel at depths from five to twenty inches. These soils vary
greatly from area to area. Riverwash consists of undifferentiated sand,
gravel, and cobble. Fluvaquent soils can support some vegetation, but
Riverwash supports practically none. Both Fluvaquent soils and River-
wash have poor potential for use as homesites or other developments.
The high water table and flooding history make the use of septic tank
and leach fields potential threats to groundwater and surface water
quality.
A-19
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The rubble land and rock-soil outcrops which flank the flood plain,
terrace, and foothill areas consist of the Haploborolls rubble land
complex, the Fortwingate-Rock outcrop complex, the Garza-Clayburn Rock
outcrop, the Goldvale-Fortwingate-Valto outcrop association, and the
Uinta-Leadville-Anvik association.
The Haploborolls rubble land complex is the most extensive soil-
rock type in the Animas River Valley. The complex, found on mountain
slopes, consists of shallow to deep, well-drained soils mixed with
colluvial deposited boulders, stones, and cobble. This unit is used
almost entirely for rangeland and wildlife. The complex has poor poten-
tial for use as homesites and other developments as a result of steep
unstable slopes.
The Fortwingate-Rock outcrop complex consists of a moderately deep,
well-drained soil and rock outcrop on moderately sloping to moderately
steep mountain slopes. Typically, the surface of Fortwingate is covered
with one to three inches of organic material. The surface is typically
a dark-brown, stony, fine sandy loam about one inch thick. The lower
portion of the surface horizon is generally a pinkish-gray, fine sandy
loam about eight inches thick. The upper portion of the subsoil is
typically a brown loam about 20 inches thick. The lower portion of the
subsoil is typically a strong brown, stony, clay loam about ten inches
thick. Sandstone bedrock usually occurs at a depth of 32 inches. The
soil is suited for vegetation and wildlife. Permeability of the
Fortwingate-Rock outcrop complex is moderately slow to slow. Surface
runoff is moderate and erosion hazard is low. Available water is mod-
erate. This soil complex has a poor potential for the development of
homesites and other buildings. The primary soil limiting features are
depth to bedrock and slope. Construction problems may be encountered
when laying utility lines, sewage lines, and foundations.
The three soils complexes of the northern part of the Animas River
Valley, the Goldvale-Fortwingate-Valto, the Garza-Clayburn Rock outcrop,
and the Uinta-Leadville-Anvik complexes, all consist of mixtures of loam
and rock. The soil complexes are found on steep mountain slopes and are
generally well-drained.
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The Goldvale-Fortwingate-Valto complex generally has a poor poten-
tial for homesite development. The Goldvale soil has a high shrink-
swell potential, which makes it somewhat unsuitable, for road and founda-
tion construction. In addition, slow percolation of this soil limits
the use of septic tanks and absorption fields. The Fortwingate and
Valto soils also have poor potential for the development of homesites
and other buildings primarily because of steep slopes and depth to
bedrock. The nearness of bedrock to both of these soils makes seepage
from septic tanks or lagoons a threat to groundwater quality.
The Garza-Clayburn Rock outcrop has fair potential for use as
homesites and other developments. The main limitation in areas of this
complex is slope, which is often too steep for the development of septic
tanks and absorption fields.
The Uinta-Leadville-Anvik complex has poor potential for homesite
construction and other development, with slope being the main limiting
factor.
Florida River Valley
Generally, the soils of the Florida River Valley consist of loam
and a small amount of Fluvaquent soils in the flood plain area, and rock
outcrops at the flood plain's perimeter. Loam and Fluvaquents make up
approximately eighty percent of the Study Area while the rock outcrops
make up the remaining twenty percent.
Specific types of soil in the area are Hesperus loam, Werlow loam,
Fescar fine sandy loam, Plome fine sandy loam, Goldvale very stony fine
sandy loan, Nordic stony fine sandy loam, Alamosa loam, and Claybum
cobbly loam. Pescar fine sandy loam, Werlow loam, and Fluvaquents are
discussed under the Animas River Valley. Nordic stony fine sandy loam
and Alamosa loam exist in such insignificant quantities that these soils
will only be described briefly.
Hesperus loam is a deep, dark colored, and well-drained soil lo-
cated on gently sloping to moderately sloping mountain slopes, alluvial
fans, and valley bottoms. It is formed in medium textured alluvium.
Typically, the surface is a dark grayish-brown loam about thirteen
inches thick. The top portion of the subsoil is typically a dark-gray
A-21
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clay loam about eight inches thick. The middle portion of the subsoil
is typically a grayish-brovm clay loam about thirteen inches thick. The
substratum is typically a pale-brown sandy clay loam. The soil is used
primarily for native rangeland, dry cropland, irrigated cropland, and
homesites. Permeability is slow to moderate in this soil. Surface
runoff is medium to rapid and the erosion hazard is slight. Available
water capacity is high. Generally, Hesperus soil has a poor to fair
potential for use as homesites and other developments. The slow per-
colation rate of some Hesperus loam may create potential pollution
hazards to the groundwater if septic tanks and absorption fields are
Installed.
Nordic stony fine sandy loam ie a deep, well-drained soil which is
located on moderate to moderately steep slopes. It is formed from
colluvium and alluvium derived from sandstone. Generally, the surface
is covered with one to three inches of organic material. The surface
layer is typically a very dark grayish-brown, stony, fine sandy loam
about nineteen inches thick. The lower portion of the surface layer is
a brown, stony, sandy loam of about twenty inches. The subsoil is typi-
cally a brown, stony, clay loam about twenty-five inches thick. The
soil is used as woodlands and, in small areas, for homesite develop-
ments. Permeability of the soil is moderate. Surface runoff is slow
and the erosion hazard is low. Available water of the soil is high.
This Nordic loam has a poor potential for the construction of homesites
and other development. The limiting factors are slope and the presence
of large stones. These limitations make the soil unsuitable for the
development of absorption fields and the construction of septic tanks.
Goldvale very stony fine sandy loam is a deep, well-drained soil
found on steep to very steep mountain slopes and sides of alluvial
valleys. It is formed from colluvial-alluvial material derived from
interbedded sandstone and shale. Typically, the surface is covered by a
zero to four inch thick layer of organic material. The surface layer is
a reddish-gray, very stony., fine sandy loam about three inches thick.
The middle portion of the surface is pinkish-gray, very stony, fine
sandy loam about ten inches thick. The lower portion of the surface is
mixed light-brown and pinkish-gray, stony, sandy clay loam about four
A-22
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inches thick. The upper portion of the subsoil is a mixed light-brown
and pinkish-gray, stony, sandy clay loam about four inches thick. The
middle portion of the subsoil is a reddish-brown clay about fourteen
inches thick. The lower portion of the subsoil is mixed reddish-brown
and yellowish-brown stony clay. Most of this soil unit is used in wood-
land or homesite development. Permeability is moderate. Surface runoff
is medium to rapid and the erosion hazard is low. Available water
capacity is high. Limiting features of the soil for residential devel-
opment are its shrink-swell potential and slope. In addition, percola-
tion might tend to be slow. Septic tank and absorption field construc-
tion should be designed to overcome the limiting features.
Plome fine sandy loam is located on mountain slopes. A deep, well-
drained soil, Plome formed in eolian sediments. Generally, the dark
grayish-brown surface layer is about four inches thick. The upper part
of the subsoil is light reddish-brown sandy loam about fourteen Inches
thick. The substratum is reddish-brown sandy clay loam that extends to
a depth of sixty inches or more. This soil is used mainly for irrigated
crops, dry crops, woodland and native pasture. Permeability is moder-
ately slow. Surface runoff is moderate and erosion hazard is slight.
Available water capacity of the.soil is high. The Plome soil has fair
potential for use as homesites and other developments. The soil's
primary limitations in this regard are its high shrink-swell potential,
slope, and inability to support a load. The limitations are fairly
readily overcome by use of engineering measures, and septic tanks and
absorption fields can be accommodated.
Clayburn and Alamosa cobbly loams occupy only a small part of this
segment. Clayburn soil, found on mountain slopes and toe slopes, has
moderately slow permeability, and has generally a fair potential for use
as homesites and other developments. The limiting factor for septic
tank absorption fields is slope. Alamosa soil is generally found on
level or nearly level areas. It has moderately slow to slow permea-
bility, and generally has a poor potential for use as homesites. The
primary limiting factor is the high water table. Septic tanks and
absorption fields have the potential for jeopardizing groundwater qual-
ity when placed in this soil.
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The soil-rock outcrops which border the valley are the Carracas-
Sanchez, Valto, and Fortwingate. Additionally, rock outcrops exist.
The Fortwingate-Rock outcrop complex has been described under the Animas
River Valley.
The Carracas-Sanchez complex consists of well-drained soils on
gently sloping to steep mountain slopes. They are formed in residium
overlying interbedded sandstone and shale. The Carracas soil has a
surface covered with one to three inches of organic material. Typically
the surface is a dark gray-brown loam about three inches thick. The
underlying material is a yellow-brown clay loam about six inches thick.
The Sanches soil has a brown, stony, sandy clay loam surface about five
inches thick. The subsoil is a dark grayish-brown clay loam about ten
inches thick. Sandstone bedrock usually occurs with seventeen inches of
the surface. Permeability is moderate, down to bedrock. Surface runoff
varies from rapid to very rapid, and erosion hazard is moderate. Avail-
able water of the soil is low. This complex has a poor potential for
homesite and other development. Depth to bedrock is the primary limit-
ing feature. This factor plus steep slopes make the soils unsuitable
for the construction of septic tanks and absorption fields. On areas
where these soils occur near drainages, seepage from septic tanks may
cause groundwater quality problems.
The Valto-Rock outcrop complex has shallow, well-drained soils on
mountain slopes and ridges. It is formed in material weathered from
sandstone. Typically, the surface layer of Valto soils is covered by a
two to four inch thick organic layer. The surface layer is a dark
reddish-gray, stony, fine sandy loam about two inches thick. The upper
part of the underlying material is a light reddish-brown, very stony,
fine sandy loam about ten Inches thick. The lower portion of the under-
lying material is fractured sandstone bedrock. This complex is used
primarily for woodland and, in small areas, for homesite development.
Permeability is moderate to moderately rapid. Runoff is moderately
rapid and the erosion hazard Is low. Available water is low. The
Valto-Rock outcrop complex has a poor potential for the development of
homesites and other buildings. The primary limiting factors are the
soil's slope and possible seepage into groundwater. Thus, septic tanks
and absorption fields may be potential threats to groundwater quality.
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Rock outcrops have shallow soils too variable to rate. Vegetation
is sparse and the rock unit has a poor potential for use as homesites
and other developments. Its main limitations are lack of soil material,
steepness of slopes and general rocky characteristics. No septic tanks
or absorption fields could operate in this type of outcrop.
The Florida Mesa
The Mesa generally consists of loam, clay and clayey loam soils
with some small areas of rock outcrop. The specific soils of the area
are Falfa loam, Heldt silty loam, Werlow loam, Midway clay loam, Big
Blue clay loam, and Gaynor clay. Werlow loam has been described under
the Animas River Valley.
Falfa loam is a deep,, well-drained soil on mesa tops. It formed
from eolian materials that originated from redbed deposits. Typically,
the surface layer is reddish-gray loam about six inches thick. The
upper part of the subsoil is reddish-brown clay loam about five inches
thick. The middle part of the subsoil is reddish-brown clay about
twenty inches thick. The lower part of the subsoil is reddish-brown
clay about twenty five inches thick. The substratum is pink loam to a
depth of sixty inches or more. This soil is used mainly for irrigated
crops, nonirrigated crops, and range. Permeability is slow and avail-
able water capacity of the soil is high. Surface runoff is moderate and
erosion hazard is moderate. Incorporating residues into and on the
surface helps reduce erosion. The Falfa soil has a fair potential for
use as homesites and other urban developments. The soil's main limita-
tions are the clayey subsoil with high shrink-swell potential and its
slow permeability. Foundations, septic tank absorption fields, roads
and streets must be designed to overcome these limitations.
A-25
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Heldt silty clay loam is a deep, well-drained soil usually located
on valley slopes and upland valleys. This soil formed in fine textured
alluvium from shale hills. Typically, the surface is light olive-brown,
silty clay loam about eight inches thick. The subsoil is a light olive-
brown, heavy silty clay about twenty inches thick. The substratum is a
light yellowish-brown, silty clay to a depth of sixty inches or more.
In some areas on the steeper slopes, these horizons may be thinner.
This soil is used mainly for irrigated and nonirrigated crop land.
Permeability of the Heldt soil is very slow. Surface runoff is moderate
and erosion hazard is moderate. Incorporating residues into the soil
controls erosion. Heldt soil has a fair potential for use as homesites
and other development. Slow permeability, clay layers, and high shrink-
swell potential are the primary limitations. Septic tank absorption
fields, foundations, and roadbeds must be designed to overcome these
limitations.
Midway clay loam is a shallow, well-drained soil located on ridges
and hills in shale bedrock uplands. It formed in residium on shale.
Typically, the surface layer is light brownish-gray clay about three
Inches thick. The underlying material is light gray clay that overlies
soft shale at about eight to twenty inches. Permeability is very slow.
Surface runoff is rapid and erosion hazard is high. Vegetation growth
is necessary on these soils to reduce erosion. The Midway soil has a
poor potential for use as homesites and other developments. The shallow
depth of bedrock, steep slopes, and high shrink-swell potential of this
soil are its main limitations. Foundations, septic tank absorption
fields, and roads need to be designed to overcome these limitations.
Big Blue clay loam is a deep, poorly-drained soil located on low
terraces and valley bottoms. It formed in fine textured alluvium from
shale. Generally, the upper part of the surface layer is dark grayish-
A-26
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brown clay loam about eight Inches thick. The lower part of the surface
layer is dark grayish-brown silty clay about eight inches thick. The
subsoil is gray silty clay about ten inches thick,. The substratum is
gray calcareous silty clay to sixty inches or more. Gleying and mottles
are common in the subsoil and substratum. The soil is used mainly for
Irrigated pasture and rangeland, and wetland wildlife utilize these
soils. Permeability of Big Blue soil is slow. Available water capacity
is high. Surface runoff is slow and erosion hazard is slight. This
soil has a fluctuating water table during most of the year and is sub-
ject to occasional flooding during spring and summer months. The Big
Blue soil has a poor potential for use as homesites or other develop-
ments. The soil's main limitation is its susceptibility to occasional
flooding. Intensive and costly engineering design measures are needed
to overcome this limitation in order to develop septic tank absorption
fields.
Gaynor clay, a moderately deep, well-drained soil, is located on
slopes of shale hills. It formed in residium from shale. Typically,
the upper part of the surface layer is gray clay about three inches
thick. The lower part of the surface layer is dark clay about three
inches thick. The underlying material is dark gray clay overlying shale
bedrock between depths of twenty to forty inches. The soil is used
mainly for irrigated pasture and hay, with some range land use. Perme-
ability is very slow. Available water capacity is moderate. Surface
runoff is moderate and erosion hazard is high. Pasture and hay land
management as well as proper irrigation methods are necessary to mini-
mize erosion. The Gaynor soil has a poor potential for use as homesites
or other community developments. The main limitations of this soil are
depth to bedrock and high shrink-swell characteristics. Major modifica-
tions are needed in the design of septic tank absorption fields, founda-
tions, and road beds to overcome these limitations.
A-27
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The main rock outcrop of the area is the Midway Rock outcrop com-
plex, which consists of shallow well-drained soil on shaley foothills
and shale and sandstone rock outcrops. Typically, the surface area is
light brownish-gray about three inches thick. The underlying material
is light gray clay that overlies soft shale at about eight to twenty
inches. The soil is used primarily for range. Permeability is very
slow. Available water capacity is low. Surface runoff is rapid and
erosion hazard is high. Vegetation growth and the incorporation of
proper grazing use can help minimize erosion problems. The Midway Rock
outcrop complex has a poor potential for use as homesites and other
developments. The shallow depth to bedrock, slope, and shrink-swell
potential of this soil are its main limitations. Septic tank absorption
fields, foundations, and roads need to be designed to overcome the
limitations.
Lightner Creek -
The Lightner Creek Valley consists of loamy soils flanked by soil-rock
outcrops. The loam soils make up approximately sixty-five percent of
the area, while the soil-rock outcrops make up the other thirty-five
percent.
Specific loam soils of the area are the Pescar fine sandy loam,
Fortwingate stony fine sandy loam, Anvik loam, Nehar stony fine sandy
loam, Cold Creek Variant stony fine sandy loam, Hesperus loam, Goldvale
very stony fine sandy loam and Midway clay loam. The Pescar soil has
been discussed under the Animas River Valley, Hesperus and Goldvale
soils have been discussed under the Florida River Valley, and Midway
clay loam has been discussed under the Florida Mesa.
Fortwingate stony fine sandy loam is a moderately deep, well-
drained soil located on gently sloping to very sloping mountain slopes.
A-28
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It is formed in mixed facial material, sandstone, and loess. Typically,
the surface is covered with one to three inches of organic material.
The surface is generally a dark-brown, stony, fine sandy loam about one
inch thick. The lower portion of the surface horizon is typically a
pinkish-gray, fine sandy loam about eight inches thick. The upper
portion of the subsoil is typically a strong-brown, stony, clay loam
about ten inches thick. Sandstone bedrock usually occurs at a depth of
thirty-two inches. This soil is used as woodland and, in small areas,
for homesite development. Permeability is moderately slow to slow.
Available water is moderate. Surface runoff is moderate and erosion
hazard is low. This soil has a poor potential for the development of
homesites and other buildings. The primary soil limiting features are
the shallow depth to bedrock and slope. Septic tanks and absorption
fields must be designed to avoid seepage and overcome slope limitations.
Anvik loam, a deep, well-drained soil, is found on moderately steep
to steep mountain slopes. It is formed in colluvial-alluvial material
derived from sandstone and shale. Typically, the surface is covered by
a two to four inch thick layer of organic material. The surface layer
is a dark-brown loam about thirteen inches thick. The lower portion of
the surface horizon is a light yellowish-brown sandy loam about eight
inches thick. The upper portion of the subsoil is a light yellowish-
brown and brown sandy clay loam about four inches thick. The middle
portion of the subsoil is a brown sandy clay loam about thirteen inches
thick. The lower portion of the subsoil is a brown sandy loam over
sixty inches in depth* This soil is used for woodland, and in small
areas for homesite developments. Permeability of the Anvik soil is
moderate. Surface runoff is slow and erosion hazard is slight. Avail-
able water capacity of the soil is high. Anvik soil has a poor poten-
tial for homesite construction and other development. Slope is the
primary limiting feature.
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Nehar stony fine sandy loam is a deep, well-drained soil found on
terraces along major drainages. It formed in cobbly and stony glacial
outwash material. Typically, the upper part of the surface is pink,
stony, fine sandy loam about two inches thick. The lower part of the
surface layer is light reddish-brown, stony, fine sandy loam about five
inches thick. The subsoil is reddish-brown, stony, clay loam about
twelve inches thick. The substratum is very cobbly and stony sandy loam
extending to sixty inches or more. Permeability is slow to moderately
slow. Available water capacity is moderate. Surface runoff is slow and
erosion hazard is slight. The Nehar soil has fair potential for use as
homesites and other developments. The soil's primary limitations are a
moderate shrink-swell potential and an inability to support a load.
Septic tank absorption fields, foundations, and streets need to be
designed to overcome these limitations.
Cold Creek variant stony fine sandy loam is a deep, well-drained
soil found on mountain slopes. It formed in stony colluvial material
composed mostly of sandstone. Typically, the surface is covered by a
two or three inch layer of organic material. The surface layer is
typically grayish-brown, very stony, fine sandy loam about two inches
thick. The lower part of the surface is a very pale-brown, stony, fine
sandy loam about 22 inches thick. The upper part of the subsoil is a
pale-brown, extremely stony, clay loam about eight inches thick. The
lower part of the subsoil is a brownish-yellow, extremely stony, clay
loam about ten inches thick. The substratum is a very stony clay loam
about eight inches thick. This is underlain by shale and sandstone at
depths ranging from forty to sixty inches or more. The soil is used
mostly for wildlife habitat, woodland, and range. Permeability of Cold
Creek variant soil is moderately slow. Available water capacity is low.
Surface runoff is moderate and erosion hazard is moderate. The growth
of vegetation can reduce erosion problems. Cold Creek variant soil is
not especially suited for homesite development. Steep slope, rockiness,
A-30
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and hazards of landslides are limiting factors. In addition, shallow
depth to bedrock makes the soil unsuitable to septic tank and absorption
field construction.
The specific soil-rock outcrop complexes of the area are the
Carracas-Sanchez complex, the Fortwingate-Rock outcrop complex, and the
Haploborolls rubble land complex. The Carracas-Sanchez complex is
described under the Florida River Valley; Fortwingate-Rock outcrop
complex and Haploborolls rubble land complex are described under the
Animas River Valley.
Junction Creek
The valley consists of loam bordered by soil-rock outcrops and
badland. Loam makes up approximately sixty percent of the area, while
soil—rock outcrops and badland make up the other forty percent.
Specific types of loam in the area include Pescar fine sandy loam,
Midway clay loam, Fortwingate stony fine sandy loam, Hesperus loam,
Connerton loam, and Big Blue clay loam. The Pescar and Connerton soils
are described in the Animas River section; Hesperus soil is discussed in
the Florida River Valley section; Midway and Big Blue soils are discuss-
ed in the Florida Mesa section; and Fortwingate soil is discussed in the
Lightner Creek section.
Soil-rock outcrop complexes in the area are Carracas-Sanchez com-
plex, Haploborolls rubble land complex, Fortwingate-Rock outcrop com-
plex, and Valto-Rock outcrop complex. The Fortwingate and Haploborolls
complexes are discussed in the Animas River section; the Carracas-
Sanchez and Valto complexes are discussed in the Florida River Valley
section.
A-31
-------
Badland consists of steep and very steep barren land dissected by
many intermittent drainage channels that have entrenched into the Mancos
shale. About ninety percent or more of this unit is unvegetated. On-
site investigations are needed for more detailed interpretations to
determine use and planning at proposed sites.
FLOOD PLAIN
The U.S. Army Corps of Engineers has prepared three flood plain
information reports for the Animas River and selected tributaries with-
in the EIS/201 Study Area, (References 5, 6). Tributaries of the Animas
River for which the designated 100- and 500-year flood plains are mapped
include Junction Creek, Hermosa Creek, Dry Gulch Creek, and Lightner
Creek. The Animas River flood plain is mapped from Baker's Bridge to
the La Posta Road Bridge below Durango. One hundred year flood plains
for the Study Areas are shown in Figures 4.7 through 4.11 in the EXS.
The Florida Road area does not include the flood plain of any of these
waterways. Flood plain data are not available for the Florida River.
However, the Florida River's flow is regulated by £emon Reservoir,
located about fourteen miles (22.5 km) northeast of Durango just outside
the Study Area. The reservoir is approximately one-half mile (0.8 km)
wide and three miles (4.8 km) long with a capacity of 40,000 acre-feet
(4.9 x 10^ cubic meters). Runoff from the upper drainage area is
stored, and regulated releases provide irrigation water below the im-
poundment as well as municipal and industrial water for Durango. The
facility also provides fish and wildlife habitat, recreational oppor-
tunities and flood control.
The Animas River and its tributaries have relatively small flood
carrying capacities. However, high volume/velocity flows and floating
debris that have caused relatively minor floods have resulted in sub-
stantial property damage. This has probably occurred because much of
A-32
-------
the development within the narrow Animas Valley has been on the flood
plain. Development in flood plains can potentially restrict flood
flows, increase water velocity, alter flood plain boundaries and con-
tribute to property losses. Flooding of treatment plants, interceptor
sewers, collection lines, and on-site sewage disposal facilities can
cause an interruption in treatment of wastewater and create public
health hazards. The earliest recorded flood on the Animas River
occurred in 1884. Subsequent large floods occurred in 1896, 1909, 1911,
1927, 1937, 1941, 1946, 1949, 1970, 1972, and 1973. The flood on
October 5, 1911, is the most severe recorded in the area. During that
flood event, a peak flow of 25,000 cubic feet per second was recorded at
the Durango stream gage. Tributary flows were also high during that
flood. Major snowmelt floods occurred in 1941 and 1949 in the Animas
River, while snowmelt floods on Hermosa Creek occurred in 1920 and 1941.
A major flood resulted from a rain storm on melting snow in June of
1927, when the peak flow in_ the Animas River reached 20,000 cubic feet
per second.
VEGETATION
Vegetation in the Rocky Mountain region is influenced by elevation,
^posure, temperature, soils, topography, and land use. For purposes of
this EIS, broad general vegetation units will be separated using alti-
tude variation. This approach will allow an identification of vegeta-
tion in horizontal zones. Within each zone smaller subunits of vegeta-
tion can be identified and their components inventoried.
The Durango 201/EIS Study Area ranges in elevation from about 6,400
feet in the Animas Valley south of Durango to about 8,800 feet. The
Principal vegetation communities of the Study Area include ponderosa
Pine forest, pinyon-juniper woodland, mountain shrub, sagebrush, ripar-
ian woodland, and croplands.
A-33
-------
Vegetation inventories have been conducted in relationship with the
Animas-La Plata Project. These inventories cover the plant communities
which are common to this EIS/201 Study. The large variations in elevation,
topography, exposure, and temperature have produced a large number of
habitats suitable for many different plant species. Vegetation studies in
the Study Area indicate about 557 species present. These plants are listed
in Table 2.
Well-developed, mature and comparatively undisturbed Ponderosa pine
forest is an open forest with an understory of shrubs and herbs. Gambel's
oak is the dominant shrub associated with this stand type. This forest
provides the bulk of deer and elk habitat and is highly important for wild
turkeys. Some herbaceous parks occur in this zone in the valley bottoms.
Below the Ponderosa pine forest is the more open pinyon-juniper
woodland. On the dryer Ponderosa pine sites the pinyon-juniper will
integrate in higher elevations while on moister sites the Ponderosa pine
will integrate down. On deeper soils the pinyon pine dominates the
stand while on steeper slopes and rocky soils the juniper component
dominates. There is usually a shrub layer of Gambel's oak on higher soils
or mountain mahogany and other shrubs on rocky soils. The mixed-browse
understory is a major big game food supply and range.
The mountain shrub consists of two distinct plant communities in
southwest Colorado. On areas with heavy, poorly drained soil,
Gambel's oak dominates, while on lighter, better drained soils and rocky
soils mountain mahogany dominates.
Sagebrush is scattered through the area and is found in close
association with all plant communities below 9,500 feet. It often
A-34
-------
TABIC 7
PUWTS OF T>€ STUDY AREA
Scientific Nan*
S®9»
and
Other Bottomland
IHe Relative Pondarosa Mixed Plnyon Mountain low Riparian
Fori* Abundance Pine Cool(ar Juniper Brush Brush Grass Vegetation
Abies concolor
A brow le traqraas
Acer qlabr—
Acar arandldewtatuw
Acar nequndo
Achillea I ami lose
Achillea »lll«lotl«a
Actlnaa acaulls
Actlnaa rIchardsoaI
Aoosarls auraatlaca
Aooserls glauca
Agrocyroa crlstatun
Anropyroa latarwadlun
Anropyroa HWKtorepens
Aqropyron repans
Aqropyroa wlthll
Aorooyrow trachycauluw
Aqrostls alba
Alates nacdougalI
tillua acMolwatua
Allluw awarl
Wilt* fir
Rocky Mountain aeple
BI g- toothed Mfle
Boxalder
Terrox
Yarrotf
Ptnque
Plaque
Mountelft-dandel Ion
MountaIn-dande I Ion
Crested vfceetgress
latersedlate
wtwetgrass
Falsa fackgriss
Quackgrass
Western utieetgrass
Slender vhaatgrass
Red to»
HIId anion
Wild onion
T
F
T
T
T
F
F
M
H
F
F
0
e
r
R
A
A
P
R
P
C
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
-------
Scientific
II »•
farm
r
U)
ON
Allluai textile
Alnus tanulfolia
Alyssma alyasoldes
Awaranthui
qraaclrans
Awarantlwi
ratrotlenus
Awbrosla
coronopltolla
Awe IanchI ar
alnltolla
AnaphalIs
¦arqarltacea
Androooaon oarardl
Andropoqon scopar I us
Androsaca
septentrional Is
Androstephlui
bret 11 lorua
AntennerIa dleorpha
Aatannarle earvl fol la
Antiwar I« rosea
-------
Scientific Name Co—on Man
Arab!* diver Icarpa
Arab!* lwi<|»f|
Arabls hirsute
Areblt kolbonlin
Arabls Manlier*
Ar»bl» pulchre
Arebl* selbvl
Arceuthoblua
c—pylopoduai
Arceuthoblua
vaqlnatua
Aranarla coiwMti
Arg—one Inter—dl»
Arlstlda landtar Iana
Arlstlda IoneIseta
Art—Isle ciM
Art—I sin cerrutkl
Art—l»l« drecunculu*
Art—Isle frlqlda
Art—Isl* ludovlclana
Art—Isle nova
Art—Isle wliwcewa
Art—tsl» trldntati
*wlnlw capr Icornu
Ascleplas *peclosa
Rockcrtft
RocfcCTMt
Rocker as a
Rockcrass
Rockeress
Rocktran
Rocker***
D«arf alstletoe
0«art alstlatoa
Sandwort
Prickly poppy
Fendler thraaaua
Red threaa*a
Sllvar sagebrush
Carrntk sagebrush
6re— segewort
Frlaged sagebrush
Co—on Horxood
Black sagafervsk
Bud sagabrusk
Big sagebrush
Milk vaad
Giant altkweed
Saga
and
Othar Bottoaland
Ralatlva Ponderosa Mixed Plnyon Mountain Low Riparian
Abundance Pine Conifer Juniper' Brush Brush Grass Vegetation
C X XXX
P X XX
C X XXX
C X X X X
P X XX
R XXX
P X XX
R X
R X XX
P XX
P X X X X X
A X
A XXX
P X X
p X XXX
A XXX
C X XXX
P X
R XX
OX XXX
C X
C X X
-------
SclMtltlc Mmm Co—oh Nim
Asclaplas vartlclllata Whorlad ¦lllamd
Asparagus oHIcImIIi Asparagus
Aster arawosus Astar
Astar blgalovll Astar
Attar lalcatus Milta astar
Altar glaucodas Altar
Astragalus blsulcatus Mllkvatch
Astragalus calycosus Matted allkvetch
Astragalus Blua poslonvatch
contortIIlorus
>
| Astragalus 11axuosus Vatck
W
00
Astragalus dru—icindl Vatch
Astragalus gracilis Mllkvatch
Astragalus Spacklapod loco
lantlolnosus
Astragalus Mllkvatch
I onchocarpus
Astragalus Missouri allkvatch
¦Issourlaasls
Astragalus oocaIycIa Polsonvatch
Astragalus pattarsonl Patterson
polsonvetck
Astragalus sctsollas Loco
Astragalus scopulory loco
Atrip lax canascaws Four-winged
saltfarush
TABLE 2 (Continued)
LI
Form Abundance Pin
a Relative Pondarosa Mixed Plnyon
Saga
and
Other
Moontala Low
Botto* Iand
Riparian
ConI far Junlpar Brush Brush Grass Vagatatlon
R
R
R
It
C
R
P
P
P
C
P
D
X X
X
X X
X X
X
X X
-------
Lll*
Sclaatlf Ic Mm* (*n—na Nmm Fora
Atrlplait coafartllolla SMtttlt S
Atrlplan corruguta Nat salttruah H
Atrlpla* mittilll Mutt*I* saltbrusk M
Atrltlw rem Annual salt far ink H
A*— latua HI 14 Oat F
Bal> I a dlssacta F
Batsaaorrhlia Balsaa root F
saqlttata
B of bar I» tandlar I Colorado barbarry S
Batata I on t Ilia 111 Rocky aouatala brick T
I Blapharoaauroa Pla* dropsaad G
W trlcholaals
Boutaloua Sltaati graaa 0
curtlpaadula
Boufloaa graclll» Blua graaa 0
Brlcfcallla Brlchalltruali HS
bracfcyphlla
Brlcfcallla BrlckalI brush HS
calllornlca
Brlcfcallla Brlckal I brush f
araaJIflora
Brlcfcallla Brlckalbrush F
obloaoHolla
Brlcfcallla scabra BrlckalI brush HS
Browui anoaalus Moddlng brosa 0
Bron carlnatus California broaa 0
TABU 2 (Continued)
Saga
and
Other Bottoaland
Ralatlva Pondarosa Mlxad Playon Mouatala Lm Riparian
Abutdaaca Plaa ConI far Junlpar Brush Brush Grass Vsgatatlon
0 x
ft X
R X
R XX
C XXX
P
C X
P X X
C X X X X x
A X
C X X X X
* X X X X
R X X
ft x XX
R X XX
R X XXX
II XXX
* X X X X
ft X X X X
-------
TABLE 2 (Continued)
Sclaotltlc Hum
LI I* Relative Ponderosa Mixed Playon
Form Abundance Plna CooI far Juniper
Sage
and
Other Bottomland
Mountain Low Riparian
Brush Brush Grass Vegetation
Broaus CIIlatus
Broam I nereis
Browa Japonlcus
Broaul earqlnatus
Broeii tectorue
Calochortus ounnlsonll
Calochortus nutalll
CamelIna mlcrocarpa
Caepanula rotundlfolia
Capsella bursapastorls
Cardamlae cordltolla
Cardarla draba
Care* never!
Carex festival la
Caren hellophlla
Caren occidentalIs
Caren praegraclI Is
Castlllela chrowosa
CastI lie la
llnarlaetolla
Fringed brome
Smooth braaa
Japanese chess
Mountain broai
Cheetgrass
Nerlposa Illy
Segollly mar Ipose
False flax
Harebell
Shepard's purse
Blttercress
Hhltetop
Geyer's sedge
Orange Indian
paintbrush
Ceanothus fandlerl
Centaurea plcrls
Ceraitlua arvense
Hsu Jersey tea
Russian knapweed
Mouse-ear chic leveed
Carcocerous tntrlcatm Mamtah mahogany
GL
Mountain aeadou sedge GL
Elk sedge GL
Elk sedge GL
Clustered field sedge GL
Red India* paintbrush
P
A
R
A
0
P
P
P
R
C
C
P
A
P
R
P
P
C
A
C
R
C
R
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
X
X X
X X
X X
X X
X X
X X
-------
ABLE 2 iConttnuodt
Saga
and
Other Bottoalaiul
Sclaatlflc Mom
Pn—on NbM
LI fa Ralatlva
Font Abundance
Pondarosa
Plna
Mlxad
Coalfar
Plnyon
Junlpar
Mountain
Brush
Low
Brush
Riparian
Grass Vagatatloa
Carcocarpus aontanus
Trua aountala
aahogany
S 0

X
X

Chaaaactls iwalMll
Falsa yarrow
F P
X

X
X
X

Chal lantbai faal
Llr fara
P P
X
X

Chanoeodlua albua
Laabsquartars
F A
X

X
X

Chanopodlua barlaMtlwl
Goosafoot
F C
X

X
X
X
X
ChMoottJIuai capltatua
Goosafoot
F P
X
X
X
X

Chwueodtw Irnntll
Goosafoot
F A
X

X
X

Chanoaodlua atsucua
Gooaafoot
F P

X
X
X
X
ChuoBQdlii
Isotookyllim
Gooiafoot
F R
X
X
X
X
X

Chanopodlua prafarlcola GaoMfoot
F C
X

X
X

Chortipari taMlIx
Chorltpora
F P

X
X
X

Chrvsopsls vlllou
Hairy goldaa attar
F A
X

X
X
X

Chryiothaanui
daprassus
Dwarf rMltkrut
H R

X
X
X

Chrytothaum mumousus
Rubbar rabbltbrush
s
A
X

X XX
Chrysothaanua
vlicldl1lorn*
Rabbltfcrush
S A
X

X
X
X

Clchorlua Intybus
Chicory
f •*

X
X
X
X
Clnlua mam
Canadian thlstla
F C
X

X
X
X
X
Clrslua lanceolatua
Bull thlstla
F C
X

X
X
X
X
Clrslua naaaaxlcaaua
Thlstla
F P

X
X
X
X
Clrslua Mldwllua
Thlstla
F P
X

X
X
X
X
-------
TMl£ 2 (Contlnuod)
Sag*
and
Other Bottcaal and
SclMtiflC HdM
Coma* Mom
Lit*
Fora
Relative
Abundance
Pondarosa
Pine
Mixed
Conifer
Plnyon
Juniper
Mountain
Brush
Low
Brush
Riparian
Grass Vegetation
Clrslua undulatua
Wavy-leaved ttllltu
F
P
X

X
X
X
X
Claytonla iancaolata
Spring beauty
F
P
X

X
X

X
ClaaatU klrsutlMlaa
Leather flowar
f
P
X

X
X

Claaatls llaustlclfolia Vlroln'a bower
y
A
X

X
ClaaatU Maudoalolna
Virgin'* bowar
*
P
X

Clacma lutaa
T
-------
Sclantlflc Nbm
LI fa
form
OJ
Crvptaatha bafcarl
Crwtwtla fandlarl
Cryptiwthi llwi
Cryptinttn gracilis
Cwoolosiwi
officinalis
Oactvlls gloaarata
Danthonla Intanaadla
Patura MttlpHw
OalpMaly — Isonl
Oaacrualala plmata
Dascuralala wrtl«
Plstlchlls strlcta
Drab* r«ttw>
Praha noloba
Echlnocactua ¦asaavardaa
Houndatoagua
Echlnocactus slaotonll
CdiInocactus irhlpolal
Echlnocaraum cocclnaui
Edtlnocafui faadlarl
EcMnocbloa cfusqal 11
Elaaaonus snoustllolla
Elaocharls ¦scrostaclwa
Elllila nycatala
Orchard gra«a 0
Tlabar oatgrau Q
Thornappta
Llttla larkipur
Taasy austard
Tansy austard
Inland saltgrass
UNItint-grass
Whitlow-grass
Barrel cactus
Barral cactus
BarralI cactus
Had hadgaftog cactus
Hadgahog cactus
Barnyard grass 6
Russian ollva S
Splkaaadga GL
F
TABU 2 {Continued!
Saga
and
Othar Bottoai I and
Ralatlva Pondarosa Mixad Playon Mountain Lou Riparian
Abundance Plna Conllar Juniper Brusli Brush Grass Vegetation
P X X
P X XX
C X XXX
P XX
P X X X
P X XX XXXX
R X X X X
R XX
OX XXX
P X XXX
AX XXX
I
P XXX
P XXXX
R X X
R XX
P XX
P XX
P X X
R XX
C XX
P X X X X X
C X XX XXXX
R X X X X XXX
-------
Scientific Maae
Co—on Nsaa
Lite
Form
Elvaus canadensis
Canada ulldrye
e
Clyaus sallnus
HI Id rye
0
Ephedra torravana
Joint!Ir
S
Ephedra vlrldls
Brlghaa tea
s
Eplloblua horneaanaf
Duarl fIreweed

Eplloblua panlculatua
Autuan ffreveed

Equlcetua arvense
Horsetail

Eoulsetua laevlaatua
Horsetail

Erlqeron dlveraens
Spreading fleetana

Erlaoron eatanll
Flaabana

Erlaeron enaelaannll
Fleabana

Erlqeron speclosus
Flaabana

Erlqeron utahensls
Flaabana

Erloqonua alatua
Hinged arlogonua

Erloqonua carnua
Uefarella plant

Erloqonua corvabosue

Erloqonua flavua

Erloqonua (usIforae
Desert truapet

Erloqonua Intlatum
Desert truapet

Erloqonua Jaaesll

Erloqonua
lonchophvllua

Erloaonua alcrotherua
Slenderbush erlogonua

Erloqonua receaosua
Red-root erlogonua

TABLE 2 (Continued)
Sag*
and
Other Bottom I and
Relative Ponderosa Mixed Plnyon Mountain too Riparian
Abundance P|ne Conifer Juniper Brush Brush Grass Vegetation
-------
TABU 2 {Continued)
Scientific
Sag.
and
Othar Bottoaland
LIIt Ralatlva Pondarosa Mlxad Plnyoa Mountain Low Riparian
form Abundanca Plna Coal far Junlpar Brush Brush Grass Vagatatloa
frtoooww iwlwt latu
trodlai clcutarluw
Crysla
asparw
Errs lay lacoasal
Euoatorlua harhacaua
Euphorbia landlarl
tuphorbla rotusti
Eurotla I anata
Fandlara rupIcoIa
fastuca ar I ton lea
fastuca Idahoaaslsa
fastuca octoflora
fastuca thurbarl
forastlara aanawnlcaaa
frawla a—rlcua
fraqarla ovalf«
fraxlaus (innaala
frltlllarla
atropurauraa
Galllardla arlstata
Calluai aparlaa
Gallua coloradoaasa
6aura cocclaaa
Caura wmaaxlcaoa
Sulfur flomr
StorksblII, fllaraa
Hastara uallfloMr
Mailtlouar
Spurga
Sfurga
Mlatarfat
CI lit faadlarbush
Arlzoaa fascua
Idaho fascua
Slx-uaaks fascua
Thurbar's fascua
Coyota bush
Stravbarry
Straubarry
Slaglalaaf ash
Frltillary
Blaakatflouar
Bad strait
Colorado badstrau
Buttarfly uaad
TalI buttarfly waad
H
S
e
0
e
0
c
A
P
R
R
C
P
ft
P
R
R
P
C
P
P
c
R
R
P
P
P
C
P
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
X X
X X
X X
-------
Scientific Hhh Po—oa Wmi
GayopKytuw rBmsliilnu
Goran I uw c—spltow
Garanlua traaioatll
Garaaliaa norvosy
Syalua rldnrftwll
Gil la aggraoata
Gl |la conoasta
Gil la haydanII
Ollla lactooerla
Gil la witwmM
6111a slauala
Gllla taxana
Slacaaa hadaracaa
Gray I a splnosa
Grlndalla arIionlea
Grlndalla aquarota
Gutlarraila sarothraa
Hah—nroa hyparboraa
Hacfcalla f lorlbunda
Hactalla qraclIanta
Hacfcalla laptophylla
Hatogaton qlcoaratus
i Ground Mofc a
HI 14 garanIua
Wild garaalua
Ml 14 garaalua
Wild garaalua
Scar I at trvptt
Ilowar
Dansal y~t lowarad
gllla
Nakad-staaawd gllla
Obscura gllla
Tax as gllla
Ground Ivy
Hop-lag*
Guavaad
Brooa snafcaw aad
Bag orchid
Stlcktlgfct
Falsa lorgat-aa-aot
Hackal la
Halogaton
T«LE 2 (Contlnuadl
Saga
and
Othar Bottaailand
Ralatlva Pondarosa Mixed Plnyon Maun fain Low Riparian
Abundance Plna Conlfar Juniper Brush Brush Grass Vegetation
X X
P
P
R
P
C
P
R
P
P
P
P
P
P
A
P
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
-------
TABLE 2 (Continued)
T
45-
LI
SclMtlflc Nhn
For* Abundance Pin* ConIImc Junlpar Brush Brush Grass Vagatatloa
HaplooapPiis ifwrloldw Goldwweed
Haolooaopu* gracilis 6oldan«aad
Haalopappus auttallll BoNnimri
Hrttoa drii—nartll Mock-panayroyal
Hadvsanm boraala Saaat wtck
Hallanthalla unlllora Llttla sua!lowar
Hallaatfcus annus Common samtlowar
Htl lanttms nut tall II Llttla samf lovtr
tlallanthus aatlolarla
Haraclaua lanatuw Couparsalp
Hlaracli— fandlarl Hankvaad
Hauchara paryltolla Aluaroot
Hilar la |a«asll Gal lata
HlmirU vulgaris MorastalI
Holodlscus duwosus Rock splraa
HorJaw lubatm Foxta 11 bar lay 6
Hor<— wIIIImi Llttla bar lay 0
Hordaui vuloara larlay S
Hydroahvl lua faadarl Katar laaf F
Hyaenoaappus tllllollus f
Hvaaaoxvs vacantia Plnqua H
Hvaagyyt rlchardsoall Plnqua H
I liana rlvularls Wild hollyhock F
Saga
and
Othar Bottaaland
Ralatlva Pondarosa Mlxad Plnyon Mountain Lou Riparian
P
P
P
P
P
P
P
P
P
R
P
P
A
R
R
A
R
R
P
P
P
P
R
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
-------
TABIC 2 (Continued)
¦O
00
SclaatlHc Naa*
LIla Ralatlva Pondarosa Mlxad Plnyon
Form Abuodanca Pin* Con I far Junlpar
Saga
and
Other Bottealand
Mountain U» Riparian
Brush Brush Grass Vagetatlon
Irs ¦Issourlansls
Iva axillaris
tva xantMtolla
Juncus haltlcus
Juncus lonqlstvlls
Juncus saxlnontanus
Junlparus ¦ono»par«a
Junlparus scooulorm
Jun I par us ostaosparaa
Koalarla crlstata
tactuca pulchnlta
Lactuca scarlola
LappuIa radousfcll
Lathvrus laucanthus
lathyrus paucltlorus
tapldtuai caipastra
tapldluw dons 11 lory
Latldlua ¦ontany
Lapldlua partotlatu»
LaotodactvIon punqans
lasauaralta Intarnadla
Lasouaralla ract Ipas
Laucocrlnun aontanua
Rocky Mountain Iris
Poverty
-------
Sclaatlflc Nom Cow* Nhw
LI fa
Fora
«r
VO
Hqustlcuo dot tar I
Llaarla vulgaris
III— iKltll-
tlw rlolduw
LltlmMr— rii4«f«l»
tcaatly pray I
Lonlcera lavolucrata
Lotus wight II
L up I iwii n—nnhllus
LmbIwh caaspltosm
Luplnus caodatus
tuBlmn kino I
LxJwIt drn—ondl I
tyclu» Mlllto
Lxamii pHwlto
i»oe<«ail» grandIflora
Madia glQMrata
Hahoala rap an*
Halva aaalacta
M— lllarla vlylaara
Marrufaluai vulgar a
Hadlcaqo lupul liwi
Hadlcaqo latlva
Lovaga
Toadflax
Wild flax
Flax
Puccooa
Blscultroot
Tulnbarry
Daarvatck
Sand lt*lna
Staalass luplaa
Luplaa
King's luplna
Caaploa
Pala wolfbarry
Holftall
Sfcalton ^1 ant
Or agon grapa
tfaady aal low
Ball cactua
Hoarhound
Black aadIc
Alfalfa
TABLE 2 tCcmtlnuodl
Saga
and
Other Bottmaland
Ralatlva Pondarosa Hlxad Playon Mountain Lou Riparian
Abundanca Plan Conifer Junlpar Brush Brush Grass YagetatIon
C X X
C X X
C X X
R X X
R X X
P X
P X
A X
C X X
P
C X X
P X
P X X
R
R X
R X
P XX
C X X
X
X
X X
X
XXX
X
X X
X
X X
X X
X
X X
X X
X
X X
X
X XX
X X
X
X
X
X X
X
X XXX
-------
TABLE 2
-------
LI
Sclantlflc Naaa Crjmmrm Naaa Fo
Ui
WI cot I ana attaauata Ml Id tobacco
Omtlufi »IMcwlU Evan lug prlarosa
Owotlufi owltow Evan lug prlarosa
Owotlwri coroaopUolla Evanlng prlarosa
Oanothara tlava Evan lug prlarosa
Oanothafa hookarI Yallou avaalng
prlarosa
Oanothara palIIda Evan IKg prlarosa
Opuntla
-------
Sclantlftc Nsaa Co—on Nam
Lit*
Fara
Oxytrools <»H«m Grazyvaad F
Otvtrools lirtwtll CraxyvMd f
PachysUaa ifTtlnltM Hfrtl# boHlaat H
Poalcum caplllara Witchgrass G
P*rth—>ocl»*us vltacaa Virginia craspar V
Padlcularls lousawort F
Cftntranthy
fwttion aaqustUollus Pwltnai F
Pwtui barbatm I«r4llf pautam F
Pwrtwai br Ido»« 11 PuitMM F
>
I Paastaao* coMrrWtus Panstaaoa F
t-n
K>
PwntMon aatoall Panstaaoa F
Pwrt«Mii llMflato Narroolaat board's F
toagua
Panstaaoa larlclfollus Panstaaoa F
Panstaaoa strIctus Tall blua (ward's F
toagua
Paraphyllua Squarappla S
raaoslsslaua
Phacalla corruoata Scorpion weed F
Phacalla daalssa Scorploa wtd F
Phacalla hataroohy I la Scorploa waad F
Phacalla aaonxlcaiw Scorploa waad F
Phacalla splaadans Scorploa waad F
TABLE 2 (Continued)
Saga
and
Othar Bottcaland
Ralatlva Pondarosa Mlxad Playon Mountain Iw Riparian
MMndanca Plna Coal tar Juniper Brush Brush Grass Vagatatlon
X X
X X
X X
X
X
-------
Scientific Noaa fn—an Num
Phi ladalphui
¦Icrochyllm
PIllW alpllW
Pfcl— CfltHH
Phlox hoodII
Phlox lonqUolta
Phoradandron
lunlparlnun
Phraqnltos
I*
Plwsalls fandlarl
PhytalIs l«ic«ol»t»
Physarla austral Is
Physarla Moribund*
Pie— pwnqans
Plum adulls
Pi bus pondarosa
Nockorug*
Alplna tlaothy
Tlaothy
Phlox
UwglMl phlox
Aatorlcan alstlato*
fnaann raadgrass
Ground charry
Ground charry
Co—on tolapod
Tulapod
Blua sprue*
Plnyon pins
Pondaroia pin*
Plaalobothrys scopulorua
X
Plaataoo lancaolata
Plantaoo —I or
Plaataoo wrrtll
Poa annua
Poa cofWM
Poa tandlarlana
English plantain
Cn—oa plantain
WoolIy Indian xhaat
Annual bluagrass
Canada bluagrass
Muttongrnss
TABU 2 (Continued)
Sag•
and
Othar Bottomland
Ufa Ralatlva Pondarosa Mixed Plnyon Mountain Lou Riparian
form Abundanc* Plna Con I far Juniper Brush Brush Grass Vegetation
a r x x x
0 A X X X X
F C XXX
F P XXX
F C X
OR x
F R XXX
F P X X X X
F C XX
F C X XXX
T R X
TO X
T 0 X X
Popcorn Ilooar F C X XXX
FC X XX X XXX
FC X XX XXXX
F C XXXX
OCX X XXXX
8 P x XXXX
o D X XXXX
-------
Sclaatlflc Nmm Fn—on Hum
Ufa
Font
-C-
Poa tonalIInula
Po» Kitwall
Po> i*cmnta
PoiMoalua
tollosslssla
Kaatucky Mmgrui
SanAtrg'i tuagraas
Jacob's laddar
Polyqoauai av leutar* Kaotaaad
Potygow convolvulus Knotwaad
Polygonum Mwtdmw KmtMtd
Polypooon nonapallanils Baardgrass
Populus anqustKolla Narrovlaaf
cot Ion wood
Populus traaontll
Populus trawlolto
Populua wltlltnl
Portulaca olaracaa
Potwitllla gracllla
Pot—til la
paaasvlvanlca
Fraaont poplar
Quaking aspan
Rio Grand* poplar
Purslaaa
Claquafoll
ClnquafolI
Potaatllla pulcharrlaa Claquafoll
Primal la vulgaris Haalall
Praam vlrglnlanla Coaac* chokacharry
Psaudotsuoa miilwl Douglas fir
f tar I Hum aaul I Inua Brackaa far*
H«fotw« aadroaadaa Plaadrops
G
G
G
TABU 2 IContlauadl
Saga
and
Othar Bottoaland
Ralatlva Pondorosa Mlxad Plnyon Mountain Low Riparian
Abundanca Plna ConI far Junlpar Brush Brush Grass VagatatIon
P
D
A
P
R
R
R
P
P
R
X
X
X
X
X
X
p
p
c
c
R
C
-------
Scientific Mom Comkm Msaa
r
Ln
Ul
Pucclnallla distant Alkali grata
Pulsatilla ludovtclana Pasqua flowar
Purshla trldantata Antalopa blttarbusfc
Ouarcut oanballl Gaabal oak
Ouarcut turblnalla Oak
Ranunculus cvubalana Shora buttarcup
Ranunculus tastlculatus Buttarcup
Raphaaus rachawlstrun HI 14 radish
Ratlblda ooluanltara Pralrla cooatlowar
Rhanus snlthll
Rlbas auraun
Rlbas carom
Rlbas lapthaathw
Rhus radlcans
Rhus trllobata
Roblala aaoaaxlcana
torlna nasturtliw
aquatlctm
Ror I do a obtma
Rosa aclcutarls
Rosa nutfcana
Rosa woods11
Rudbacfcla laclalata
Ryan acatosal la
Salth's buckthorn
GoIdan currant
Early currant
Goosabarry
Wastam poison ivy
Skunkbush suaac
Haw MaxIcan locust
Watarcrass
Watarcrass
Mild rosa
Wild rosa
Mild rosa
Coaaflowar
Dock
TABU 2 (Continued)
Saga
and
Other Bottoaland
LI la Ralatlva Pondarosa Mlxad Plnyon Mountain Lou Riparian
For* Abundanca Plna ConI tar Junlpar Brush Brush Grass Vagatatlofl
OR X X X X X ^
f C X X X XX
S A XX
SOX XX
R XX
C X X X X XXX
P XX
R X X X X X
R X X X X X
R XX
P X XX
C X XX
P X X
R X X X
AX XX
R X X X X
C X XX XXXX
P XX
S C X X X X X
S P X X X XX
S C X XX
f « X XX x
f C X XX x
-------
TABIf 2 (Continued)
Scientific Nam
Common Hams
Life Relative Ponderosa Mixed Plnyon
For* Abundwc* Pine Conifer Juniper
Ruma* crhpui Curly dock
Rumex Ivyeeivosapalus Canalgre
Sal Ik aarvodalolde*
Sail* exlgua
Sallx li
PeacMeaf willow
Sandbar illlon
Red willow
Yellow w11 low
Russian thistle
Lenceleaf sage
Blue elderberry
Sal Ix lutea
Salsola kail
Salvia reflexa
Sawbucus coerulea
San leu la Mr I land lea Snake root
Saponarla vaccarla Soapwort
Sarcobetus verelculatus Black greasewood
Sclrpus acutus Herdatas butIruth
Sclrpus aawrlcanus Three*square bul(rush Gt
Sctrpu* paludosut Marsh bulIrush
Sclrpus valldu*
toer lean jyeat
bulI rush
F
F
S
S
s
5
F
F
S
F
F
S
GL
GL
GL
P
ft
A
A
R
ft
A
ft
ft
P
A
0
R
C
C
P
Scutellaria qalerlculata Skullcap
X
Sedge stenopetalua Stonecrop F C
Seneclo long Hobos Groundsel F P
Seneclo tiltllobatus Groundsel F P
Seneclo wutabllls Groundsel F P
Shtptwdit argontt JIhtr MUlcbrry 5 P
x
X
X
X
X
X
X
X
X
X
Sage
and
Other Bottoeland
Mountain Low Riparian
Brush Brush Grass Vegetation
-------
Scientific Mbm
Co—on Hm«
Ufa
For*
Sldatm cand I da ftlM laal low
Sldalcaa ft«o—Klcaw Fit i« Ml low
SUww antfrrhlna CaaploA
Sllana aomUtll Catch#ly
SI lane noctlflora Canploa
Slsywbrlmi iltlMlm Tuabf* Mustard
Sltybflua |lnlch I uw *antafttf« BI ua-ayad grass
Ln SI tan I o*» hyitrlx Bott I abr ush
^ squlrraltall
Sal lac Ina racaaosa Falsa Soloaan's
saal
SaHaclna stallata FiIm SoIomwi'i
•aat
Solanua Jaaesll Wild potato*
Solanua trlflorua Mlghtsftada
Solldaqo canadensis GoIdenrod
Solldaqo alssourlensls Goldenrod
SoIIdago petradorla Rock goldenrod
Solldaqo sparslflora Goldenrod
Sonchus asper Sow thistle
Sphaeralcaa cocclnea Scartat globaaallow
Sphaeralcaa parvHplla Hallow
TABlf 2 (Continued!
Saga
and
Other Bottoaland
Ralatlva Poodarosa Mixed Pinyon Mountain Low Riparian
Abundance Plna Con I far Junlpar Brush Brush Grass Vagatatlon
P
P
C
P
R
C
C
C
-------
Scientific Nam
Co—tow Nbm
>
I
Ln
00
Spfyobolui >lral Alkali uctton
Sporobolus cryptandrus Sand dropiMd
SIachy> plaustrls Batony
Slanleya pinnate Dasert prlnci^U
Stanleyella wrlghtII
Stellorla |w>Um Chlcfcweed
Stel Uf(e »»4li Chlctweed
SUphanowerli tmuKolli
Stlpa cotuotlam
Stlpa coaata
Stlpa letter laanl
Stlpa MOMxican*
Stlpa robuif
Stlpa speclosa
Stlpa ylrldula
Subalplrve naedle-
grass
Needle and thread
letteraan neddle-
grin
New Mexico
feathargrata
Sleepy grata
Dasert needltgraas
Green needlegraaa
Streptanthus cordatui Talstflowar
Swart I a albojwarqlnata Green gentian
SyephorIcarpos
oreophllu»
Mountain snowberry
Tatar Ix pentandra Salt cedar
Taraxacum officinale Convaon dandaf loo
tent Gray horMbrtak
TABU 2 (Continued)
Saga
and
Other Bottoaitand
Llfa Relative Pondarosa Mixed Plnyon Mountain low Riparian
Fora Abundance Pine Conifer Juniper Brush Brush Grass Vegetation
G P X X X X
G P X X XXX
P X XX
p x X X X
R X X X X
C X X X X
c x x x x
rflre lettuce PCX XXX
G R X XX
G A X X X X X
G P X XX
G P X XXX
G R X X XX
G R X X XXX
F R X X X X
F R XX
S P XX
ST 0 XXX
f C X XX XXXX
-------
TABlf 2 (CoAtlnu»dt
>
I
*wO
vo
Scientific
Ufa Relative Poodtrosa Mixed Plnyon
Form Abundance Pino Conifer Juniper
Sagt
end
Other Bottomland
Mountain Low Riparian
Brush Brush Grast Vegetation
Tatradyla iplnota Cottonthorn hor»a-
brush
Taucrlnua canadente Germander
Thallcteue datycarpue Talla aeAdov rua
Thallctruw fandlarl Meadow rua
Thelypodlim rhowboldeum Thaiypodium
Thwoptli dlvarlcarpa Golden pea
Thermopsla iontaw Mountain golden
Thlaspl alpettre Panny cress
Townsendla Incana Eastar daisy
Townsendla aerlcea fatter daisy
Traoopoqon pratarts Is Goatsbeerd
Trlfollue pratenie Red clover
TrI folium repent White Dutch clover
Trlglochln aarltlia Arrogress
Typha enqustHolla Cattail
Typha latlfolla Co—on cattail
Urtlca dlolca Stinging nettle
Varbascum thapaus Mullein
Verbena bracteata Big bract verbena
Verbena urlghtIj Vervain
Veronica a*aarlcana Speedwell
Vernolca anaqallls- Speedwell
aquatlea
GL
GL
GL
ft
R
P
R
C
R
C
C
C
P
P
P
R
P
A
P
C
R
R
P
P
X
X
X
X
X
X
X
X
X X
X X
X X
-------
TABU 2 (Continued)
Scientific Name
Common Name
Life
Form
Relative
Abundance
Ponderosa
Pine
Mixed
Conifer
Plnyon
Juniper
Mountain
Brush
Sage
and
Other
Low
Brush
Bottomland
Riparian
Grass Vegetation
Veronica serpyl11 folla
Speedwell
F
P
X
X
X
X

Vlcla amerlcana
American vetch
F
P
X
X
X

Vlqulera wultlflora
Goldeneye
F
P
X
X
X
X
X
X X
Viola adunca
Western long-
spurred violet
F
C
X
X
X
X

Viola canadensis
White violet
F
c
X
X
X
X

Woodsla oreoana
Hood fern
P
p
X
X
X

Wyethla amolexIcAulIs
Hulesears
F
R
X
X

Hyethla arlionlca
Arliona mules*
ears
F
P
X

X
X

Xanthlum Itallcum
Cocklabur
F
P

X
X
X
X
Yucca anoustlsslM
Narrow leaf yucca
H
C
X

X
X
X

Yucca baccata
Broad-* leafed yucca
H
C
X

X
X

Yucca harrlmanlae
liarrlman yucca
H
R

X
X
X

Zvaadenus oramlneus
Grassy deathcamae
F
P
X

Zvoadenus panlculatus
Oeatti cmms
F
R
X

X
X
X

T - Tree
S~ Shrub
f - Forb (harbtctouf flowering plant
other than a grata)
0 - Grass
H - Half shrub—a "wft_ ha I (-woody, shrub
Relative Abundance Symbol Definitional
R - Rare - The species Is present, on the average. In I of 20
plots In Its community. Harb plots Measure I
square meters shrub plots Measure 20 square Meters
and tree plots measure 200 square Meters.
P - Present - The species Is found In approximately 9 of 4
plots In the proper community.
C - Common - The spec las Is found In approximately I of 2
plots In the proper community*
A - Abundant - Th# specfes 1$ present In approximately 2 or
mot* o( » U Ut cMMunlty.
-------
occupies the better, moister soils and also occurs in park areas, pri-
marily a consequence of overgrazing. It also is a common component on
flatter areas such as mesa tops with pinyon-juniper, The dominant plant
is the Big Sage which occurs in clumps, interspersed with grass. The
amount of grasses is inversely related to the amount of overgrazing.
Under less grazed conditions perennial grasses will be more abundant.
Sagebrush and pinyon-juniper create important winter range for big game.
Riparian woodlands are confined to the alluvial flood plain of
rivers and waterways. Typical vegetation includes cottonwood, willow,
cattails, rushes and sedges.
While not a natural stand type, cropland does constitute an inte-
gral part of the Study Area ecosystem dynamics. There are primarily two
types of cropland, irrigated and dryland. Irrigated croplands are
typically found adjacent to riparian areas and normally consist of
alfalfa and native hay. Nonirrigated drylands are scattered on mesa
tops in association with sagebrush and pinyon-juniper. These areas
produce grain crops and pinto beans and attract mule deer, particularly
during early spring and late fall green-up periods.
The various community types undergo successional changes as they
evolve towards climax status. Several factors can play critical roles
in this evolution. Four predominate man-related disturbances, over-
grazing, fire, logging, and urban expansion, can induce very different
community types leading to development of strikingly different landscape
appearances.
Overgrazing occurs rather extensively in the Study Area. In the
ponderosa pine forest it produces an increase in oakbrush, pine drop-
seed, needle and threadgrass and blue grass, and a decrease in mutton
grass. Overgrazing has little effect on the ponderosa pine itself. In
A-61
-------
the pinyon-juniper and mountain shrub zones there is a significant
reduction in the perennial grasses and herbaceous substory. Cheatgrass
increases, but as other species disappear there is an increase in bare
ground. Yucca increase, particularly in large areas of bare ground.
However, the dominant species experience little noticeable effect. A
similar result occurs in sagebrush communities; bare ground and annual
herbs increase and perennial species decrease.
Fire has been identified as a constant and integral component of
ecosystems in southwest Colorado, (Reference 7). Fire contributes to
ecosystem health by maintaining a vigorous vegetational pattern. How-
ever, when fire occurs more frequently than normal, due to human in-
fluence, it can become deterimental to community health. Fire in the
ponderosa pine ecotone (transitional zone) often leads to a decrease in
pine to the advantage of Gambel's oak. Successive fires will increase
the oakbrush community and decrease the ponderosa pine area markedly.
In the pinyon-juniper community, fire tends to favor brush. In the
other plant communities, a light fire causes major changes in the under-
story vegetation, and a hot fire eliminates the community. Annual plants
(cheatgrass, squirrel tail grass, tumble mustard, alyssum, etc.) are
greatly favored. From a rangeland point of view this results in a
lowering of the range quality and carrying capacity.
Logging and fire often abet one another. Following logging, there
usually is either an uncontrolled slash fire or a controlled burn.
Logging not followed by fire can also result in the development of
oakbrush community. By removing the overstory, the oak no longer has to
compete for light and becomes quite vigorous.
Burning and restricted logging have definite beneficial implica-
tions for wildlife species while overgrazing and urban encroachment are
A-62
-------
detrimental. Urban-suburban development causes the greatest long term
modification of the natural environment. The process of growth, develop-
ment, and outward expansion typically results in a total elimination of
native species.
WILDLIFE
Wildlife investigations conducted by the Colorado Division of
Wildlife and the Fort Lewis College Biology Department have identified
50 species of mammals and 64 species of birds in the Durango area.
Forty-eight of these are considered game species by the Colorado Div-
ision of Wildlife. In addition, twenty-two species of reptiles and
seven species of amphibians have been found in the area. Wildlife
species in the area are listed in Table 3. Game species are indicated
by an asterisk.
The game species inventoried in the county by the Division of
Wildlife include mule deer, elk, bighorn sheep, Rocky Mountain goat,
black bear, mountain lion, turkey, blue grouse, ptarmigan, chukar, beaver,
muskrat, mink, marten, bobcat, coyote, red fox, and grey fox.
The mule deer is probably the most abundant, most widely distri-
buted and most economically important big game species within the area.
West of Durango, in the Lightner Creek and Junction Creek drainages,
critical winter range and fawning areas have been identified. The entire
Durango area serves as winter range, while important salt lick areas
occur in the vicinity of Hermosa. These significant deer habitat areas
are identified in Figure 4.13 in the EIS.
The elk is secondary to the mule deer in abundance, distribution,
and economic importance. The major herds in the area are located
north of highway 160. A few of these animals migrate south, as evi-
denced by the road kills. The largest elk herd (1,700 to 2,000 animals)
summers in the San Juan Mountains north of the Study Area and migrates along
A-63
-------
TABLE 3
WILDLIFE SPECIES OF THE STUDY AREA
AMPHI BIANS
Tiger Salamander
Western Spadefoot Toad
Woodhouse's Toad
Red-spotted Toad
Chorus Frog
Leopard Frog
Bullfrog
common
occasional
common
uncommon
common
common
uncommon
REPTILES
Painted Turtle
Lesser Earless Lizard
Leopard Lizard
Collared Lizard
Desert Spiny Lizard
Eastern Fence Lizard
Sagebrush Lizard
Tree Lizard
Side—blotched Lizard
Short-horned Lizard
Many-lined Skink
Western Whiptail
Little Striped Shiptail
Palteau Whiptail
Striped Whipsnake
Gopher Snake
Glossy Snake
Milk Snake
Black-necked Garter Snake
Western Terrestrial Garter Snake
Night Snake
Western Rattlesnake
common
uncommon
uncommon
occasional
occasional
common
common
occasional
uncommon
common
uncommon
uncommon
uncommon
common
uncommon
common
uncommon
uncommon
uncommon
common
uncommon
uncommon
BIRDS
Great Blue Heron
*Snow Goose
~Mallard
~Gadwall
~Pintail
*Green-winged Teal
* Blue-winged Teal
~Cinnamon Teal
~American Wigeon
~Common Goldeneye
~Common Merganser
Turkey Vulture
occasional
occasional
common
occasional
uncommon
common
occasional
occasional
occasional
common
common
common
A-64
-------
Goshawk
uncommon
Sharp-shinned Hawk
common
Cooper's Hawk
uncommon
Red-tailed Hawk
common
Swalnson's Hawk
uncommon
Rough-legged Hawk
uncommon
Golden Eagle
common
Bald Eagle
common
Marsh Hawk
uncommon
Osprey
uncommon
Prairie Falcon
uncommon
American Kestrel
common
Peregrine Falcon

*Gambel's Qual
uncommon
*Ring-neck Pheasant
uncommon
*Chukar
uncommon
Killdeer
common
*Connnon Snipe
uncommon
*Band-tailed Pigeon
uncommon
~Mourning Dove
common
Great-horned Owl
occasional
Burrowing Owl
uncommon
Common Flicker
common
Lewis' Woodpecker
common
Violet-green Swallow
common
Barn Swallow
common
Scrub Jay
common
* Black-billed Magpie
common
Common Raven
common
~Common Crow
common
Pinyon Jay
common
Plain Titmouse
uncommon
American Robin
common
Townsend's Solitaire
common
Blue-gray Gnatcatcher
common
~Starling
common
Warblers
common
~House Sparrow
common
Western Meadowlark
common
Red-winged Blackbird
common
Brewer's Blackbird
common
Green-tailed Towhee
common
Rufous-sided Towhee
common
Vesper Sparrow
common
Lark Sparrow
common
Sage Sparrow
common
Chipping Sparrow
common
Brewer's Sparrow
common
A-65
-------
White-crowned Sparrow
~Turkey
~Blue Grouse
~Ptarmigan
common
occasional
uncommon
MAMMALS
Wandering Shrew
Merriam's Shrew
Townsend's Big-eared Bat
*Nuttall's Cottontail
~Desert Cottontail
~Black-tailed Jackrabbit
Least Chipmunk
Colorado Chipmunk
~Yellow-bellied Marmot
White-tailed Antelope Squirrel
Spotted Ground Squirrel
Rock Squirrel
Golden-mantled Ground Squirrel
~Gunnison's Prairie Dog
~Albert's Squirrel
Pocket Gophers
Apache Pocket Mouse
Ord's Kangaroo Rat
~ Beaver
Western Harvest Mouse
Deer Mouse
Brush Mouse
Pinyon Mouse
Northern Grasshopper Mouse
White-throated Woodrat
Mexican Woodrat
Montone Vole
Long-tailed Vole
Mexican Vole
~Muskrat
House Mouse
Western Jumping Mouse
~Porcupine
~Raccoon
~Long-tailed Weasel
~ Badger
~Striped Skunk
~Mule Deer
~Pronghom
~ Bighorn Sheep
~Mountain Goat
~ Black Bear
~Mountain Lion
~Mink
~Marten
~ Bobcat
~Coyote
uncommon
uncommon
uncommon
common
common
common
common
common
occasional
uncommon
uncommon
common
common
common
uncommon
occasional
uncommon
uncommon
common
common
common
common
common
uncommon
common
common
occasional
occasional
uncommon
common
uncommon
occasional
common
common
common
occasional
common
common
uncommon
occasional
uncommon
occasional
occasional
occasional
uncommon
occasional
common
A-66
-------
Highway 160 in the winter. The entire Study Area is used by elk, with
the most important habitat areas in the Lightner Creek, Junction Creek,
Animas River, and Florida River drainages. The significant use areas
are identified in Figure A.14 in the EIS.
Bighorn sheep are found primarily to the north of the Study Area in
the alpine and subalpine regions of the San Juan Mountains. In recent
years, individuals have been observed as far south as the junction of
the Animas River and Heraosa Creek. The most significant habitat of the
bighorn sheep within the EIS/201 Study Area is located in the Junction
Creek and Animas River drainage. This area, indicated in Figure 4.15 in
the EIS, has an estimated population of thirteen animals. The lower
areas of the tributary streams to the Animas River, north of Durango,
are designated winter range.
The Rocky Mountain goat is found to the north of the project area
in the high elevations of the San Juan Mountains. Their range probably
does not enter the EIS/201 Study Area.
Black bear are distributed throughout the San Juan Basin. Popula-
tion estimates north of Highway 160 are about one bear per five square
miles. These animals tend to confine themselves to the more remote
areas of the National Forest.
Mountain lion occurs throughout the region. The principal range of
the mountain lion is north of Highway 160. The estimated population in
La Plata County is between four and seven individuals. The mountain
lion's winter range is the same as the deer winter range. The use of
any area is probably sporadic, and only occasionally do individuals
remain in an area for any appreciable length of time.
A-67
-------
In general, the major big game habitat is located north of Highway
160. The area of highest concentration is the Animas River drainage
north and west of Durango. This area is designated as having critical
winter range, concentration areas, ind fawning and calving areas.
Upland game which occur in the San Juan basin include wild turkey,
blue grouse, ptarmigan, and chukar partridge. Wild turkey are common to
abundant throughout the region, primarily in the Gambel's oak-Pondersoa
pine vegetation. Because of their preference for this plant associa-
tion, turkeys typically occur north of Highway 160. Population esti-
mates for these areas range from seven in the Rockwood area (north of
the Study Area boundary above Hermosa) to fifty in the Lightner Creek
area. Blue grouse are found throughout the region in the Gambel's
oak-ponderosa pine community. In the vicinity of the Study Area their
range consists of the upper regions of the Animas River, Junction Creek,
Lightner Creek, and Florida River drainages. The estimated population
density is 10 birds per square mile. Ptarmigan and chukar partridge
habitat do not occur in the proximity of this project. Ptarmigan occur
above timberline north of the Study Area, and chukar occur southwest
near Cortez, Colorado.
The furbearing species in the region are beaver, muskrat, mink, red
fox, gray fox, and pine marten. The first three species are water-
oriented in their habitat requirements. Total beaver population in the
Animas River and its major tributaries in La Plata County is estimated
to be 362, and the Florida River basin has an estimated population of
194 animals. Currently, no population estimates are available for
muskrat or mink in the Study Area. Foxes occur in the rougher terrain
adjacent to river bottoms and agricultural areas. The combined popula-
tion density for both fox species is estimated to be one per four square
miles. The pine marten prefers the spruce-fir community of the higher
elevations.
A-68
-------
The two major predator species are the coyote and bobcat. Both
occur throughout the region. The coyote is the more abundant of the two
species and its population seems to be steadily increasing. The esti-
mated coyote density is approximately two per square mile. Bobcats are
most abundant in lower canyon areas and broken terrain. Major concen-
trations of bobcat in La Plata County are east and southeast of the
Study Area.
Four special interest raptors of the area are the golden eagle, the
bald eagle, the osprey, and the peregrine falcon. The golden eagle is
common throughout the area. La Plata County has an estimated population
of thirty-three birds. This species nests along bluffs and ridges and
six nesting sites were identified in the Durango area in 1974. These
nest sites are shown in Figure A.18 in the EIS.
The bald eagl& is a common winter resident of the area. In 1974 a
nesting site was identified near Electra lake, north of the Study Area.
However, there are no recent confirmed reports of breeding success in
the area. The preferred habitat of the bald eagle is along streams and
at large lakes and reservoirs. The major habitat of the bald eagle in
the area is shown in Figure 4.17 of the EIS. There is an estimated
winter population of twenty-five bald eagles along the Animas and
Florida Rivers.
The osprey is not often seen around Durango. The principal nesting
sites are north of the Study Area near Electra Lake and Vallecito. In
1974 an estimated six ospreys occurred in that area. The osprey, like
the bald eagle, prefers lakes and streams. The Animas River valley is
peripheral habitat for this species.
The peregrine falcon is known to exist in the vicinity of the Study
Area. In 1974 and 1975 a pair of birds was observed to have an active
A-69
-------
nest site west of Durango but the nesting was apparently unsuccessful.
Other old nest sites are located south of Durango, near Carbon Junction
and near Lightner Creek. An important peregrine falcon and osprey
habitat in the study area is shown in Figure 4.16 of the EIS. Recently
the Colorado Division of Wildlife transplanted six young peregrine
falcons to two prairie falcon nests in the area as part of their captive
breeding program.
AQUATIC LIFE
Fish
Aquatic life information is available from the Colorado Division of
Wildlife, (Reference 10). Fish data have been collected from fourteen
streams in the Study Area. The inventoried fish data for these streams
are presented in Table 4. Macroinvertebrate data are available from
four streams in the Study Area. The distribution of macroinvertebrates
in these streams is identified in Table 5.
The Division of Wildlife collected fish by electrofishing from six
stations on the Animas River from Baker's Bridge to the state line. In
addition, twelve tributaries in the Study Area were sampled. The fol-
lowing fish were collected in the Animas drainage: rainbow trout, brown
trout, brook trout, cutthroat trout, flannelmouth sucker bluehead moun-
tain sucker, western white sucker, speckled dace, freshwater sculpin,
and bullhead catfish. Several additional species of fish have been
planted or are known to be present within the drainage but were not col-
lected during the sampling program. These include kokonee salmon,
northern pike, channel catfish, largemouth bass, yellow perch, bluegill,
and green sunfish.
A-70
-------
TABLE 4
FISH INVENTORY BASED ON ELECTRO-FISHING10
Est. No.
Stream Segment Specle9 Per Mile
Animas River Stateline to Durango Rainbow Trout 45
Brown Trout 82
Cutthroat Trout 4
Flannel Mouth Sucker 283
Blue Head Sucker 2 112
Dace 151
Sculpin 1 131
Animas River Durango to Baker's Rainbow Trout 103
Bridge Brown Trout 170
Brook Trout 6
Cutthroat Trout 6
Flannel Mouth Sucker 18
Bluehead Sucker 4 488
Western White Sucker 18
Dace 70
Sculpin 2 464
Florida River Confluence to Hwy 160 Brown Trout 894
Rainbow Trout 40
Bullhead Catfish 13
Dace 3 643
Sculpin 845
Florida River Hwy 160 to Lemon Res. Brown Trout 563
Rainbow Trout 933
Sculpin 9 293
Junction Creek Confluence to Junction Rainbow Trout 249
Creek Picnic Area Brown Trout 20
Bluehead Sucker 399
Sculpin 508
Hermosa Creek Confluence to East Rainbow Trout 19 8
Hermosa Creek Brook Trout 123
Confluence Sculpin 6 864
Hermosa Creek East Hermosa Creek Rainbow Trout 20
Confluence to Headwater Cutthroat Trout 81
Sculpin 2 843
East Fork Confluence to Headwater Rainbow Trout
Hermosa Creek Brook Trout
Sculpin
A-71
-------
Stream
Segment
Species
Est. No.
Per Mile
186
5
25
5
176
1 690
5 738
A-72
Lightner Creek Confluence to End of
of County Rd. 207
Coon Creek
Corral Creek
Grassy Creek
Hotel Draw
Petty Creek
Relay Creek
Above Animas River
Above Hermosa Creek
Above Hermosa Creek
Above Hermosa Creek
Aboe Hermosa Creek
Above Hermosa Creek
Rainbow Trout
Brown Trout
Brook Trout
Cutthroat Trout
Hluehead Sucker
Dace
Sculpin
Brook Trout
Cutthroat Trout
Cutthroat Trout
Rainbow Trout
No Fish Taken
Cutthroat
Brook Trout
Rainbow Trout
Cutthroat
Sig Creek
Above Hermosa Creek
Brook Trout
-------
TAQLE 1
MACRO-INVERTEORATE^ OF
SELECTED STREAMS °
ANIMAS LIGHTNER JUNCTION Ft CP IDA
RIVER CREEK CREEK RIVER
D1CKRCPICRA (Mayflies) Bondad WoaaolsMn Purple CHfts Holiday Inn 32nd St. OaKer's Brdq. Upper lower Upper Lower Upper Lower
ftitct Idee
Aaelotus app. X
Oeetls App« X X X X X X XXXXXX
tphMMvella app. X X X XX XXX X
TrIcorythodes X X
ttnptagenl IdM
Cinybaa epp. X XX
tteptagftnla app*
Iron app. X X X X X X
RlthroqiiM app* X X XXX
PLECOPTERA
CMoroperl Ideo
Alloporls app, X XXX
Hastaperla app. X
>
I Porlldae
•"•J
Claassenla app. X
Per lodldae
Arcynopteryx app. X XXX
I sogonus app. XXX XX X X
I sopor la *pp. X X X X X X
Pteronercldae
Ploronarcotte *pp« X X X X X X X
NoaourldM
A!locapnla app. X
Brechyptera app. X
CApnta app. X XXX
Neooura app. X X
TRICTPTERA
Brachycontr Idno XXX XX
Brechycentrus app. X X X X X X
Mydropsychldne
Arclopsyche app. X X X XX X XXXXX
Mydropsycho app. X X X X X ( X XXXXX
Mydropt 11 Mao
-------
IRICffTCRA (ContInuori)
loptocorldoA
Oocotls app.
leptpcell« app.
Hoitcopsychldoe
IkoHcopsychn app.
LitMophl I Idrto
llosporophyl ax app.
RhyacopMHda*
Aqftpntus «|>p.
Rhyacoph11 a app,
PlPURA
81epharI cor I da«
Agalton app.
Btapharlcarld
Chiron ONildae
Helelda*
Rhag loflldM
Atherix app.
SiMJl Mm
SImmIIum app.
Str
-------
Mrttu* .^>p.
ANIMAS
RIVER
UGHTtCR
CREEK
JUNCTION
CREEK
FLOR IDA
RIVER
coucrunA
Hatpus a pp.
Opt loser vus opp,
Bondad
WtasftUkln Purple CUMs Hot May Inn 52 nd St. BnKor's Brrtg. Upper to«or Upper tower Upper lowy
UP IDGPTERA
ICMIPTCHA
OL IOGOCHAETA
OPOHATA
PUt SONATA
PELECYPOOA
IRICtADIA
X
-------
One hundred eighty-seven fish of seven species, including trout,
suckers, dace, and sculpins, were collected by electroshocking between
Durango and the state line. No evidence of natural trout reproduction
was found; all trout were identified as being planted fish or hatchery
escapees. Limiting factors for fish in this area include high summer-
time water temperatures and an unstable substrate created by large
amounts of sand and silt.
Electroshocking in the Animas River from Durango north to Baker
Bridge yielded 401 fish of nine species, including trout, suckers, dace,
and sculpin. Limited trout reproduction apparently does occur in this
section.
Twelve tributary streams in the Study Area were also electrofished.
The fish collected from these streams are included in Table 4. The
Florida River contains excellent rainbow and brown trout populations
from Lemon Reservoir to Highway 160. Below this point the increase in
water temperature and addition of low quality return irrigation water
decreases trout success and enhances nongame fish habitat. Junction
Creek has very limited flow in the summer and fall, thereby inhibiting
any trout fishery in the lower stretches. At higher elevations a trout
fishery has been maintained with catchable rainbow plants. Hermosa
Creek contains three species of trout; rainbows can be found anywhere on
the stream with brook trout at lower elevations and cutthroat high on
the drainage. Overall, the fishery is poor due to high, very turbid
spring flood flows followed by a massive reduction in water volume.
Lightner Creek contains the highest nongame fish populations of any
tributary sampled. The trout captured there can be primarily attributed
to hatchery escapees from the private unit located on the river. Reduc-
ed summer flows and poor quality water contribute to the reduced
fisheries.
A-76
-------
Population estimates have been calculated for the Animas River and
selected tributaries. These estimates are presented in Table 4. In the
Animas River, the estimates north of Durango are double those from south
of Durango. This is a consequence of the difference in habitat between
the two sections. The game fish estimates for the Animas River are
extremely low relative to the size of the river, and the nongame fish
populations are slightly higher than what is considered normal. The
high game fish estimates in the Florida River can be attributed to in-
creased productivity below the reservoir. However, the high population
estimate for Junction Creek is misleading. The creek was sampled in the
spring after the catchable plant but prior to harvest.
The entire Animas River has been managed with yearly catchable
rainbow plants supplemented with periodic fingerling brown trout intro-
duction since the early 1950's. The majority of these catchable fish
are stocked between the Indian Reservation boundary below the Purple
Cliffs and the Hermosa Creek confluence. The major tributaries have
also been managed with catchables. Most of the smaller tributaries are
planted from time to time with rainbow, cutthroat, and brook trout fry.
Harvest patterns for various trout species removed from the Animas River
and many of the important tributaries have been tabulated and are avail-
able through the Division of Wildlife, (Reference 10).
Aquatic Invertebrates
Invertebrate samples were collected on five different occasions
from six main river stations. Samples were collected in 1975 and 1976.
Additional samples were collected from Lightner and Junction Creeks and
the Florida River during 1975. Compiled data by order and genera are
presented in Table 5.
A total of 31 samples were collected from the six Animas River
stations. Sampling was done at approximately three month intervals so
all aquatic stages would be collected. Both numbers and diversity of
A-77
-------
invertebrates increased from Baker's Bridge downstream to Weaselskin
Bridge, where the greatest number of invertebrates was found. This
increase is primarily associated with rising water temperature. Below
this point, the increased temperature and excessive siltation started to
limit invertebrate production. There was also a definite change in
species composition downstream which was attributed to the change in
habitat from clear, cold water, and rock strata to warmer, turbid water,
and sandy bottoms.
In general, the invertebrate population of the Animas River can be
considered adequate for fish production. Insect populations are low at
Baker's Bridge and could possibly become limiting to fish production;
however, the blow out channelized conditions there are more detrimental
than reduced food. The numbers and distributions of invertebrates
species in the river system indicate introduction of organic pollutants
and excessive silting in the lower areas.
The Florida River had the greatest variety of invertebrates of the
three tributary streams sampled. The Florida River had eighteen dif-
ferent genera in its lower reaches and twenty-four in its upper reaches.
Lightner Creek had the lowest diversity, with seven genera found in the
upper end, and eight genera in the lower end. Junction Creek had nine
different genera in its lower reaches and eleven genera in its upper
reaches. Ecological factors affecting fish populations in the tribu-
taries are believed to exert similar influences on invertebrate popula-
tions .
THREATENED AND ENDANGERED SPECIES
Authority for the management of threatened and endangered species
in Colorado has been delegated to the State Division of Wildlife. In
addition to protecting the animals themselves, this agency's objective
A" 78
-------
is to encourage the protection of habitat considered essential to the
survival and well-being of threatened and endangered species. One
federally endangered, one federally threatened, and one state endangered
species potentially occur within the Study Area.
The peregrine falcon has been federally classified as endangered.
It is known to exist in the vicinity of the Study Area and one pair of
birds was observed west of Durango in 1974 and 197 5. Requirements for
suitable eyries are precipitous cliffs having several ledges, potholes,
or small caves in the cliff face to serve as suitable nest sites. Hunt-
ing habitat includes areas which serve to concentrate or support prey
species (primarily small to moderate sized birds) and must provide suit-
able prey exposure for aerial attacks. In the Study Area the Animas
River Valley provides both of these criteria.
The bald eagle, federally -classified as threatened, is a common
winter resident of the area. The preferred habitat of this species is
along streams and at large lakes and reservoirs.
The lynx is classified as endangered by the state of Colorado. It
is a secretive predator primarily found in spruce-fir forests above 9500
feet. Colorado Division of Wildlife distribution maps indicate lynx may
occur in the mountains north of Durango. These animals have large ranges
and may occasionally wander into the Study Area.
Currently, there are no known threatened or endangered species of
plants in the Study Area.
A-79
-------
SURFACE WATER QUALITY
Sources for surface and groundwater quality data include Colorado
Department of Health, (References 12, 13). U.S. Environmental Protection
Agency (EPA), U.S. Geological Survey (USGS) and the Colorado Department
of Water Resources. The most comprehensive surface water data are
available from EPA's STORET system but this source has information only
for the Animas River. Other surface water data sources provide informa-
tion of varying quantity and comprehensiveness. Data pertaining to
groundwater quality in the Study Area are limited and incomplete.
Groundwater quality data are available only from USGS and EPA.
Water Quality Standards
The state water quality criteria and stream classification system
were used to assess the water quality of the Study Area. The State of
Colorado promulgated water quality criteria which became effective on 20
July 1978, (Reference 11). These criteria are intended to maintain and
improve the quality of the waters of the State. Colorado water quality
criteria are shown in Table 6.
The classifications, standards, and criteria were established with
the best available knowledge to insure the suitability of Colorado's
waters for the following beneficial uses: water supply; domestic, agri-
cultural, industrial, and recreational uses; and the protection and
propagation of terrestrial and aquatic life. They are further intended
to be consistent with the Federal Water Pollution Act Amendments of 1972
and the Clean Water Act of 1977.
A-80
-------
TABLE 6
COLORADO WATER QUALITY CRITERIA
PARAMETER
Recrwt tonal
Aquatic Life Agriculture
Primary £onlact Secon
(?)
(4)
6.0 <5>
7.0-Spawn
6.5-9.0
(4 )
5.0
6.5-9.0
<4>
Aerobic
X
(4)
(?)
(?) (?)
Aerobic Aerobic
5.0-9.0
1.0 TU
5.0-9.0
(4)
r
00
Temperature (*C)
T11S (aq/l)
BIOLOGICAL
AlgM (6)
FF OtoJ. 4 TomIc FF ObJ. 4 Toxic
Mam (20 C)
w/J C l«cr«
Max 30 C
(5) w/3 C Increase <51 X
FF Oh J. 4 Toxic FF ObJ* & Toxic
FF ObJ. 4 Toxic FF ObJ.^ FT ObJ • A
Toxic Toxic
Fecal Col Moras per
100 ail (Geometric 200
n)
1000
1000
J7>
1000
(I) Wh«re dissolved oxygen levels, less then the standard, occur naturally, a discharge shall not cause e further reduction In
dissolved oxygen In receiving water*
12) An effluent shall be regulated to maintain aerobic conditions, and a guideline of 2.0 mg/1 Her dissolved oxygen In an affluent
should be maintained, unless demonstrated otherwise.
(3) A 7 ng/llter standard, during periods of spawning of coldwater fish, shall be sot on a cnse by case basis as deflnod In the
NPOES permit for those dischargers whose effluont would affect fish spawning,
(4) Susporvted solid levels will be controlled by Effluont Limitations and Basic Standards*
-------
COL OH AOO WATER QUALITY CP HER IA (ConMnuod)
(9) TMperafuri shell maintain a normal pattern of diurnal And sensonnl fluctetlons with no abrupt changes and shall have no
Increase In temperature of a magnitude, rate and duration deomnd deleterious to the resident aquatic life. Genorally, a
maxIhkjm 3*C Increase over a ¦IdIhim of a 4-Sour period, lasting for 12 hours maxim. Is deemed acceptable for discharges
fluctuating In volimio or temperature. Where temperature Increases cannot be maintained within this range using AMP, BAT£A,
and BfXTT control measures, tho Division will determine whethnr the resulting temperature Increases preclude an Aquatic tlfo
classlf(cation.
(6) Free from objectionable and toxic a I goo. It has boon well established that heavy growth of some strains of blue-green algae,
upon death and degradation, may release one or wore substances which are to*lc to humans and many other animals. Although no
fixed numbers can be recommended at this time, It Is clear that streams, lakes and reservoirs should not bo permitted to bear
heavy growth of algal blooms, nor allow these blooms to disintegrate. Every effort should be made to control algal growlhs to
levels that are not hazardous,
17) For drinking water with or without disinfection*
*
00
to
-------
COLORADO WATfR QUALITY (J3ITLRIA (Continued)

Recreatlonal

Aquatic LI
1 fe

Agrlculturo
Wat nr
Stipp 1 y
PAKAT4ETFR
Class 1
PrlM.vy Contact
SoconS
lass
lary
Contact Cold
Water WarM Water Riots

Bloassay
Agrlcultore
Class 1
(Vound
Class 2
Haw

and

Water

(1 >
>ess Imq/I 1

Water

Water tlardi

(ApplIce-

0 to 100
100 to 200
200 to 300
300 to 400
400 p1 us
lloo or2)
other)

TOXIC METALS
Total cone. In Mg/1

AluMlauM (soluble) X

0.1
0.1
0. 1
0.1
0. 1
Bloaasay
X
X
X
Arsenic
X

0.05
0.05
0.05
0.05
0.01
Bloassay
0.1
0.05
0.05 Barlu
RarluM
X

X
X
X
X
X

X
1.0
1.0 Beryl 1
Borryl 1 Ihm
X

0.01
0.3
0.6
0.9
1.1
Bloessay
0.1
X
X CadnuluM
Cacfet um
X

0.0004
0.001
0.005
0.010
0.015
Bloassay
0.01
0.010
0.010
ChromluM
X

0.1
0.1
0. 1
0. 1
0. 1

0.1
0.05
0.05
Cop pnr
X

0.01
0.01
0.01
0.02
0.04
0. IAF
0.2
1.0
1.0
Iron
K

1.0
1.0
1.0
1.0
1.0
X
Bloassay 0.1
0. 3(so1>
0.3(sol)
Lead
X

0.004
0.025
0.050
0. 100
0.150
0.05
0.05
Manganese
X

1.0
1.0
1.0
1.0
1.0
Bloassay
0.2
0.05(sol )0.05(sot)
Mot cury
X

0.00005
0.00005
0.00005
0.00005
0.00005

X
0.002
0.002
MolyhdoniMi
X

X
X
X
X
X

V
V
Y
Nickel
X

0.05
0.10
0.20
0.30
0.40
0.0IAF
0.2
X
X
Sel on 1 tm
X

0.05
0.05
0.05
0.05
0.05
0. IAF
0.02
0.01
0.01
Silver
X

0.00010
0.00010
0.00015
0.00020
0.00025
0.0IAF
X
0.05
0.05
Thai 11um
X

0.015
0.015
0.015
0.015
0.015
Bloassay
X
X
X
(51
UranluM
X

0.03
0.02
0.4
0.0
1.4
Bloassay
(5)
(5)
(51
Z inc
X

0.05
0.05
0. 10
0. 30
0.60
0.0IAF
2.0
5.0
5.0
(1) ConcentratIons of total alkalinity or other chelating agents attributable to Municipal, Industrial or othnr discharges or
agricultural practices should not alter the total alkalinity or othnr chealtlng agents of the rtc*lvlng water by More than 201.
Where tha compie*Ing capacity of tha receiving water Is alternd by Mora than 20% or where chelating agents are released to the
receiving water which are not naturally characteristic of that water, specific effluent ll«ltatlons on ertlnnnt arameters will bo
established. In no case shall InstreaM Modification or alteration of total alkalinity or other chelating agents he permitted
without Com I ss Ion aulhorliatlon.
(2) Where Indicated, bloessay procedures nay be usod to established criteria or standards for a particular situation.
(31 Tor bloessay lead concentratIon Is based on soluble lead Measurements (I.e. non-f11terable lend using a 0.4) Micron filter).
(4) The appropriate value for Molybdenua depends on mnny factors, such as soil type, crop and Irrigation practices. A nix»erlcal
value for mo I yhdenm will bo assigned on a case by case bask,
()) UranluM Is listed In Table II for Its to* Icolog leal proportlos to aquatic life, and also In Tablo V (Rad lolog leal s) for
I ImI tat Ions on oflior usm.
-------
coinnAno water quality critfria (Continued)
Recreational Aquatic Life Agrlcullure
PAHAME TtH Prl«i«ryB2oni»ct Secondary'^ontacf Cold Water Olots War« Wafer Blots Agriculture Groun95&nlw Rnw'fil?or
I MO) HAN ICS
Ammonia (mg/l as N)
-Total residual
CM or I no (mj/1 I
Cyanide («g/l)
Fluoride («j/l )
Nitrate <*g/t as M)
HI trite (ng/l as N>
Sulfide M )
Roron (av|/l)
Chlorld« (*g/l)
Maqnestom (ing/t )
SodIum Adsorption Ratio
Sut fata (
(I) Because M«o«la nay be Indicative oI pollution and bocause of Its significant effect on chlorlnntlon, It Is recc«n»eni|od
that anonli nitrogen In public water siippply soirees not exceed 0.5 «q/l.
<2» Fluoride tlolta vary fro* 2.5 «g/l at 12.0 C and below, to 1.4 «g/1 between 26.3 C and 32.5 C.based upon the annual
average of the miIm dally air teapnraturn (see "National Interim primary drinking water regulations tor specltlc
limitations", or any Modification thereto).
(31 In order to provide a reasonable margin of safety to allow for unusual situations such as nxtremoty Igh water Ingestion
or nitrite formation In slurries, the W) -M plus MO N content In drinking waters for livestock and poultry should be
Halted to 100 ppa or loss, and tho Hfl^ H content alone be Malted to 10 ppm or loss.
<«> Phosphorous criteria or standards are to be delnralned by an algal bloassay using the mothod described in the latest
edition of "Standard Mnlhods for tho Examination of Water and Wastewater", American Public tloalth Association.
X X 0.02 unionized 0.10 unionized X 0.3 0.5* *
X X 0.002 0.01 X XX
X X 0.005 0.005 0.2 0.2 0.2
x x x x x ,2>
XXX X ,00°' 10 10
x X 0.05 0.5 I0m 1.0 1.0
X X 0.002 unrfissocIated 0,002 urxjlssoclated X 0.05 0.05
X X X x 0.75 XX
* XX x X 250 250
xxx X X 125
* XX X X XX
* x X X X 250 250
Dloassay Bloassay Bloassay Bloassay X Bloassay* * RIoassayMI
-------
COLORADO WATfB QUAI.ITY 0HT01IA (Contlnuod)
R«crMl I on a I
>
I
00
m
PARAMETER
CIass )
Primary Contact
Llass /
Secondary Contact
Aquatic life
Cold Water Olots
and
Warm Hator Blots
Agriculture
AgrIculture
Class I
Ground Hater
Class I
Ran Water
ORGANIC
0.001
(t) All organic*, not on this partial list, are covered undor Basic Standards.
(2) Mumarleal values la tablet based on experimental evidence of toxicity. No point source discharges of organic
pesticides shall be permitted to state waters.
<3) The persistence, bloacctimuf at Ion potential, and carcinogenicity of thesn organic compounds cautions human exposure to a
Minimum (EPA),
|4) Aldrln and dloldrln In combination should not nxcood 0.000003 mq/l.
<5) Every reasonable effort should be made to minimize human exposure (EPA).
-------
COLORADO WATER QUAUU CR I TfR (A (Conllnuod)
PARAMf TER
R«cr«atlonaf
Class I , Class 2
Primary Contact Secondary Contact
Aquatic Ufa
Cold Water Glnts
Warm Water Blots
eonc. In Plcocurles por
II tor
AgrIcultor®
Class I Class I
Agriculture Grotmd Water Rnw Wafer
>
I
CO
radiological
Alpha ' ^ (excluding X
uranium & rndon)
<*>
Bote (excluding X
strontlum 90)
Costurn, 134 X
Plutonium 238, 259, & 240 X
Radium, 226 1 228 <5> X
Strontium 90 X
Thorium, 230 4 232 X
Tritium X
Uranium (total) X
15
50
00
15
5
0
60
20,000
15
50
80
15(61
5
8
60
15
50
B0
15
5
0
60
15
50
80
15
5
8
60
20,000 (El 20,000 20,000
5 mq/l
<9>
w. m wm
(1) Concentrations given ere Mvlaw permissible concontrat Ions above naturally occurring or "backgrdowd" concentrations
excet where otherwise noted.
(2) It Alpha or Bote ere measured In excess of 15 or 50 pCI/l resectlvely. It will be necessary to determine by specific
analysis the particular radionuclide or radionuclides responsible lor the elevated leva. Particular radlonuclIdes
should not exceed the value given In the table. If an elevated level of Alpha or Beta emissions Is caused by
radionuclides, the Division should be consulted.
(3)
Maximum permissible concentrations Including naturally occurring or background contributions.
-------
MAltR QUALITY STANDAHOS StMMMY
Sfandard
Sottlenble Solids
Floating Solids
Taste, Odor, Color
Tox Ic Materials
Oil and Grease
RadloactJvo Hatorial
fecal Col Ifora
Rocterle
Turbidity
Dissolved Oxygen
pH
Te«(mratur(i
Fecal Streptococcus
Class
I
Free Fro*
Free Froa
Free Fro*
Free Fro*
Cause a f I la or
other dlscofor-
•t Ion
Drinking Water
Standards
GoonotrIc Mean
of <200/100e|
from five
samples In
50-day per
No Increase ol
•ore than
10 J.T.U.
Fro* Fro*
Fro* Fro*
Free Fro*
Free Froa
Ceuse a fI la or
other discolor-
ation
Or InkIng Mater
Standards
Geometric Mean
of 200/I00«I
froa flvt
samples In
30-day per
No Increase
more than
10 J.T.U.
Free From
Free From
Free From
Free From
Causa a fI la or
other dlscolor-
at ton
Drinking Wator
Standards
Geomatrlc Mean
of <)000/100n»l
froa five
samples In
30-day per
No Increase
aore then
10 J.T.U.
Froe From
Free From
Free Froa
Free Frnm
Cause a Ilia or
other dlscofoi—
at Ion
Orlnklng Water
Standards
Geometric Mean
of
-------
TARt£ 6 (C
I
00
00
-------
Animas River
Water quality data on the Animas River are, available from the
Colorado Department of Health and from EPA. Water quality of the Animas
River has been monitored at nine stations within or adjacent to the
Study Area. Water quality monitoring stations are located on Figure 7.
Data collected at these stations are presented in Table 7. All but one
of the monitoring stations (station 66) are located within the original
Study Area.
Station 66, while not within the original Study Area, is included
in the data base because of its period of record. Also, comparison of
data between station 81 at Baker's Bridge and station 66 at Bondad can
provide an overall perspective of water quality changes through the
Study Area. The remaining stations on the Animas River aid in identi-
fying the locations of water quality changes.
Most of the Animas River surface water information is from EPA's
STORET system. Data from studies done by the Colorado Department of
Health are limited. There is duplication of data among Department of
Health documents, and no more than two samples were taken by the
department from any one sampling station.
The existing water quality data base is comprised of various param-
eters monitored during different time periods, and is generally incon-
sistent both spatially and temporarily. However, based on these data
some conclusions can be made on the quality of water in the Animas
River.
Evaluation of data for station 81 at Baker's Bridge indicates the
following:
A- 89
-------
•7( A-5)
HISTORIC WATER QUALITY
SAMPLING POINTS
4(LC-2)
2(LC -4)
Stations l2(A-2), 13,
and 66 are several miles
south of the Study Area
ANIM06
Hwy 160
09362510
3(LC-3) I
5 (LC -Oj
9 (A3)
c/>
M
-------
TABLE 7
WATER QUALITY DATA
ANIMAS RIVER
PARAMETER
STATION
81
Mean
Max.
Min.
09361500
Mean
Max. Mln.
Temperature, *C
5.4
16.1
0
9.94 17 3.6
Dissolved Oxygen, mg/1
10.57
12.2
7.4
9.2
pH, units
7.9
8.9
6.9
8.4
Total Alkalinity, mg/1
44
44
44
56
Total Hardness, mg/1
150.6
263
59
95.0
Calcium Hardness, mg/1
118.7
238
9.8
32.0
Magnesium Hardness, mg/1
7.3
23
2
3.6
Tota1 Sol Ids, mg/1
213
258
119

TDS, mg/1
196.24
370
79
124,0
Conductivity, u mhos
285.5
467.00
130.0
491.8 770 223
Sodium, mg/1
3.26
13
1
2.0
Chloride, mg/1
4.34
12
1
40.0
Sulfates, mg/1
99.78
230
25

Turbidity, FTU
8.07
18
1

Nitrate, mg/1
0.167
0.8
0
0.09
Nitrite, mg/1
0.003
0.0033
0

Armnonla-N, mg/1
0.08
0.72
0

Ortho Phosphate, mg/1

0.03
Total Phosphate, mg/1
0.075
0.25
0

Total Phosphorus, mg/1
0.058
0.23
0
0.01
BOO, mg/1
1.32
8
0

Total Collform, W=N/100 ml
1175.5
2400
2

Fecal Collform, MPN/IOOml
79.48
2200
0

Aluminum mg/1

Arsenic mg/1
0

Cadmium mg/1
0.00016
0.0003

0.07
Chromium mg/1
0

Copper mg/1
0.0094
0.062

1.8
Iron mg/1
0.596
2.7

45
Lead mg/1
0.0158
0. 125

Manganese mg/1
0.259
0.81

52
Mercury mg/1

0.004
Molybdenum mg/1
0.00075
0.0001

Nickel mg/1

Selenium mg/1
0

SI 1ver mg/1
0

0.06
Zinc mg/1
0.233
0.74
16

A-91
-------
TABLE 7 (Continued)
PARAMETER
STATION

ANIM06

09362510
Mean
Max.
Mln.
Mean
Max. Mln.
Temperature, *C
8.9
17.8
0.6
10.4
2.3 1
Dissolved Oxygen, mg/1

8.8
11.4 6.5
pH, units

7.9
8.7 7.2
Total Alkalinity, mg/1
121.5
207
6

Total Hardness, mg/1

Calcium Hardness, mg/1
94.7
425
8.4

Magnesium Hardness, mg/1
12.04
61
1.6

Total Solids, mg/1

TDS, mg/1
360
1,548
104

Conductivity, u mhos
428.7
640
150
748
4,800 180
Sodium, mg/1
14.06
44
1.4

Chloride, mg/1
5.56
25.5
0.5

Sulfates, mg/1
115.78
600
19

Turbidity, FTU
Nitrate, mg/1
Nitrite, mg/1
Airmonia-N, mg/1
Ortho Phosphate, mg/1
Total Phosphate, mg/1
Total Phosphorus, mg/1
BOO, mg/1
Total Collform, NPN/IOO m/
Fecal Collform, MPN/100m/
Aluminum
Arsenic
Cadmium
Chromium
Copper 0.116
Iron 1.124
Lead 0.065
Manganese 0.494
Mercury
Molybdenum
Nickel
S11ver
Zinc 0.33
882.5 4,500
92.6 500
80
0
1.5
8.6
1.0
7.7
1.16
A-92
-------
TABLE 7 (Continued)
P«PA»€TER STATION
66
Mean Max. MI n.
Tamparatura, X
8.8
21. 1
0
Olssolvad Oxygan, mg/1
10.1
12.6
8.0
pH, units
8.3
9.1
7.3
Total Alkalinity, mg/1
92.7
130
54
Total Hardnass, mg/1
219.9
369
80
Calcluia Hardnasa, mg/1
174. 1
267
64
Magnaslua Hardnass, mg/1
11.34
36
4
Total Sol Ids, mg/1
421.3
764
192
TOS, mg/1
330
544
109
Conductivity, u mhos
486.7
860
170
SodliM, mg/1
19.9
41
2
Chlorlda, mg/1
19.9
40
4
Sultatas, mg/1
119.2
190
38
Turbidity, mi
68.6 1
100
1.8
Nltrata, mg/1
0.313
4.7
0
Nltrlta, mg/1
0.008
0.0033
0
Arnnonla-#, mg/1
O.OS
1.02
0
Ortho Phoaphata, mg/1
0.03

Total Phosphata, mg/1
0.179
0.6
0
Total Phosphorus, mg/1
0.07
0.41
0
SCO, mg/1
1.76
6
0.7
Total Col 1 form, VPN/100 m/
1 268 2
400
2.2
Facal Col 1 form, MPN/IOOal
511 2
400
2
Alimlnim
2. a

ArsanIc

Cadmium
0.00008 0.0036

Chrcwlum
0

Coppar
0.0111
0.210

Iron
0.733
12.0

laad
0.0293
0.56

Manganasa
0. 1149
1.2

Karcury

Molybdanua
0.00043
0.0001

Nlekal
0

Sal an Iuia
0.0003
0.0004

SI War
0

Zinc
0.0684
0.680

A-93
-------
TABLE 7 (Continued)
STATION
7(A-J) 9- 12
-------
The mean dissolved oxygen (DO concentration of the
stream, 10.57 mg/1, is well above the minimum state
standard of 6.0 mg/1. The minimum DO concentration of
7.4 mg/1 is also above the minimum state standard. Using
standard methods the DO saturation level at the stream's
mean temperature of 5.4°C is approximately 12.7 mg/1. At
the maximum stream temperature of 16.1°C, the DO satura-
tion level is approximately 10.0 mg/1; the minimum DO
level recorded was 7.4 mg/1. These statistics indicate
that the stream segment has a background oxygen demand
resulting in a seventeen to twenty-six percent depletion
of DO below saturation.
Temperature and pH at this station, both maximum and
minimum values, are within State standards.
The fecal coliform bacteria standard is generally met.
The standards for fecal coliform require the geometric
mean to be less than 1,000/100 ml from five samples in a
30-day period. No such data is recorded in ST0RET. How-
ever, the arithmetic mean of 79/100 ml for all samples
is below the standard. The highest recorded value of
2,200/100 ml exceeds the standard, and the fecal coli-
form bacteria standard may be occasionally violated at
this station. Sources of fecal coliform include non-
point source runoff from rangeland, septic tanks, and
mechanical wastewater treatment facilities.
This segment of the Animas River meets standards of
settleable solids, floating solids, taste, odor, color,
oil and grease, and turbidity.
A-95
-------
5. A review of the metals data indicates that there are no
violations at this station of the standards for arsenic,
cadmium, chromium, manganese, molybdenum,, selenium, or
silver. Copper, iron, and lead standards are not viola-
ted by the mean reported concentrations, but the maximum
reported values are above the State limits. Zinc concen-
trations are above the standard both in mean and maximum
values reported. Thus, copper, iron, and lead concen-
tration violations are occasional, whereas zinc concen-
tration violations are more frequent. No data are
available on any other metals.
6. Nutrient levels of the stream at Baker's Bridge appear
low to moderate, with nitrate reaching a maximum of 0.8
mg/1.
7. Ammonia concentrations reach a maximum value of 0.72
mg/1. Taking the worst case conditions for temperature
and pH, this converts to twenty-three percent unionized
ammonia.
8. This station shows total water hardness to be moderate
(150.6 mg/1); conductivity (285.5 mhos) is also con-
sidered moderate.
9. Total solids and total dissolved solids have moderate
concentrations, with the mean of each being approxi-
mately 200 mg/1.
10. Sodium and chloride concentrations are low (3.26 mg/1
and 4.34 mg/1, respectively) at this station, and the
sulfate concentration (99.78 mg/1) is moderate.
A-96
-------
Changes in quality of the Animas River water as it flows through
the Study Area can be determined by comparison of the water quality at
station 81 and station 66. Station 66 is located immediately below the
confluence of the Florida and Animas Rivers. Water quality data are
available for both rivers prior to their confluence, and indicate that
both rivers have similar water quality. A comparison of Animas River
water quality above and below the Florida River confluence indicates
there is no significant impact from the Florida River discharge. Evalua-
tion of the data from station 66 indicates the following:
1. DO concentrations - both the mean of 10.1 mg/1 and the
minimum of 8 mg/1 - are well above the minimum state
standard of 6 mg/1. Saturation levels for the mean and
maximum temperatures of 8.8°C and 21.1°C, respectively,
are approximately 11.6 mg/1 and 9.0 mg/1. These statis-
tics show the existing demand on dissolved oxygen re-
sults in a twelve to thirteen percent depletion below
saturation.
2. The mean temperature and pH at this station are well
under the allowable. The maximum values of both, how-
ever, exceed the state standard. The minimum pH is
acceptable. Thus, temperature and pH standards are
occasionally violated.
3. The fecal colifonn bacteria standard is occasionally
violated. The limitations of evaluating this parameter
have been previously discussed. The mean value of fecal
coliforms has increased significantly from the value at
station 81 (from 79/100 ml to 511/100 ml). The maximum
value reported, 2,400/100 ml, also shows an increase.
A-9 7
-------
Since the mean value shows a significant coliform con-
tribution, and the maximum value is twice the standard,
it is possible that violations of the standard are not
uncommon.
4. This segment of the Animas River meets standards for
settleable solids, floating solids, taste, odor, color,
oil and grease, and turbidity.
5. A review of the metals criteria indicates there are no
violations of the standards for cadmium, chromium, moly-
bdenum, selenium, or silver. Copper, iron, lead, and
manganese standards are not violated by the mean report-
ed concentrations, but the maximum reported values are
above the limit. Zinc concentrations are above the
standard, both in mean and maximum values reported.
Copper, iron, lead, and manganese concentration viola-
tions are probably occasional, while zinc concentration
violations are probably more frequent. No data are
available on any other metals. Except for an increase
in the amount of manganese, concentrations of metals do
not change significantly between stations 81 and 66.
6. Water hardness and conductivity both have higher values
at this station than at station 81. Mean and maximum
hardness values for station 81 are 150.6 mg/1 and 263
mg/1, respectively, while station 66 recorded mean and
maximum hardnesses are 219.9 mg/1 and 369 mg/1, res-
pectively. This represents approximately a seventy
percent increase. Conductivity increased over 60 per-
cent, from 285.5 micro mhos to 486 micro mhos for the
mean values and from 467 micro mhos to 860 micro mhos
for the maximum values.
A-98
-------
7. Nutrient levels at station 66 are much higher than those
at Baker's Bridge. Nitrite values remain about the
same, but the nitrate mean value doubles and the nitrate
maximum value increases six fold, to 0.313 mg/1 and 4.7
mg/1, respectively. These parameters, along with tur-
bidity, which quadruples, seem to indicate degradation
of water quality between station 81 and station 66.
8. The ammonia mean values indicate no change, but the
maximum increases by approximately thirty percent.
Assuming worst case conditions for temperature and pH at
this station, this converts to thirty percent unionized
ammonia.
9. Total solids and dissolved solids concentrations show a
significant increase from the upstream station of sixty
to one hundred percent, respectively.
10. Chloride and sodium concentrations increased approxi-
mately four and five fold, respectively, from station 81
to station 66. This is an indication that wastewater
discharges have significant impacts on water quality.
The sulfate concentrations increased only slightly.
Data from STORET monitoring stations 90361500, ANIMOG, and 9036251
were considered only marginally useful either because the data were in-
complete or because the data were over ten years old. Data from three
Colorado Department of Health sampling stations were considered marginal
for the same reasons. However, some trends were identified using data
from these stations.
A-99
-------
Comparing data, the following trends are identified:
1. Mean temperature increases of approximately sixteen per-
cent occur before Lightner Creek joins the Animas River.
After the confluence of the Animas River and Lightner
Creek, the mean temperature varies only slightly, but
the maximum temperature of the river increases fifteen
percent. By the time the waters reach station 66, the
temperatures, both mean and maximum, have decreased.
These temperature increases are probably attributable to
natural heating of the waters from runoff.
2. The pH level of the stream remains within the standards
as it flows through the city of Durango, and remains in
compliance at station 66.
3. The DO concentration remains in compliance as the river
passes through the city of Durango. The demand on the
oxygen capacity of the river rises to over twenty-one
percent of saturation as it reaches the downstream out-
skirts of the city of Durango.
4. Conductivity of the river increases by approximately
sixty percent before the confluence of the Animas River
and Lightner Creek. Conductivity increases by another
sixty-five percent as the river travels through the city
of Durango. By the time the waters reach station 66,
conductivity has decreased approximately sixty-five
percent from the mean value recorded at the southern
edge of the city of Durango.
A-100
-------
5. Total coliforas have increased five fold by the time the
river has passed through the city of Durango. Coliform
concentrations continue to increase from there to
station 66.
6. Fecal coliforms increase as the stream passes through
the City of Durango. Concentrations continue to
increase as the stream flows to station 66.
7. Data are sparse with regard to metal concentrations, but
copper, iron, manganese, lead, and zinc all seem to
increase in concentration as the waters move downstream.
Lightner Creek
A special study of Lightner Creek was performed for the Colorado
Department of Health, Water Quality Control Division, in 1974, (Refe-
rence 13) • This study was later incorporated into the San Juan River
water quality management plan, (Reference 12). The results of one sam-
pling at five stations along the creek are presented in Table 8. The
locations of the sampling points are presented in Figure 7 along with
the approximate locations of known discharges. Although one sample
provides insufficient data from which to base concrete conclusions, some
general trends can be noted.
1. The DO concentration of the stream appears to be at an
acceptable level. No specific trend of oxygen demand
can be observed.
2. Temperature does not violate the standard. Station 5
(LC-1), which is located immediately upstream of the
confluence with the Animas River has the highest tem-
perature. This rise in temperature is probably attrib-
utable to natural warming from runoff.
A-101
-------
TABLE 8
WATER QUALITY DATA
LIGHTNER CREEK
PARAMETER

STATION

KLC-5)
2 (LC-4)
3(LC-3
4CLC-2)
5LC
Temperature, *C
15
12
17
15 '
19
Dissolved Oxygen, mg/1
7.7
8.6
7.9
7.7
8.4
pH, units
8.3
8.4
8.1
7.9
8.2
Total Alkalinity, mg/1
204
208
228
252
228
Phenolphthalein

A1 ka11n1ty, mg/1
0
0
0
0
0
Total Hardness, mg/1
316
348
392
392
450
Calcium Hardness, mg/1
300
340
376
380
310
Magnesium Hardness, mg/1
4.0
2.0
4.0
3.0
34.0
TOS, mg/1
340
365
490
475
500
Conductivity, u mhos
560
600
750
820
750
Sodium, mg/1
11
15
20
26
27
Chloride, mg/1
4.0
4.0
4.0
4.0 48
4.0
Sulfates, mg/1
85
140
200
240
240
Turbidity, F
0.6
1.2
4.0
8.0
13.0
Nitrate, mg/1
0.4
0
0
2.0
2.8
Nitrite, mg/1
0
0.02
0
0.01
0
Ammonia, mg/1
0
0
0
0.4
0.4
Ortho Phosphate, mg/1
1.4
1.0
0
0.8 0
0.8
Total Phosphate, mg/1
1.4
1.0
0.4
1.4
1.6
Total Phosphorus, mg/1
0.46
0.33
0.13
0.46
0.52
Tota1 Co 11 form,

MPN/100 ml
1560
5300
72,000
76,000
100,000
Fecal ColIform,

MPN/IOOml
20
40
7,200
53,000
52,000
Fecal Streptococca1,

MPN/IOOml
0
30
300
1,000
730
A-102
-------
3. Total coliform bacteria shows ail increase going downstream
toward the confluence with the Animas River. The total
coliform concentration increases over sixty fold between
station 1 (LC-5) and station 5 (LC-1), with the biggest
increase occurring between station 2 (LC-4) and station
3 (LC-3). This large total coliform increase probably
affects the Animas River water quality.
4. Fecal coliform bacteria also shows a marked increase
going downstream. Station 1 (LC-5) has a fecal coliform
concentration of 20/100 ml, and station 5 (LC-1) has a
concentration of 52,000/100 ml. The greatest increase
occurs between station 2 (LC-4) and station 3 (OC-3).
This increase in fecal coliform probably affects the
Animas River water quality.
5. Total hardness tends to increase as the creek flows
downstream. Increases in calcium and magnesium were
also noted.
6. Conductivity tends to increase downstream.
7. Sodium and sulfates both increase downstream, with
sulfates showing the greater change. The Increase in
sulfates is an indicator that waste water discharges
into the creek are measurable. Chloride values remain
constant.
8. Turbidity increases markedly as the creek flows toward
the confluence. This is an indicator of possible
degradation of the waters.
A- 103
-------
9. Nutrients (nitrite and nitrate) generally increase as
the creek flows toward the confluence, with nitrate
appearing as the more significant nutrient. The in-
crease of nutrients is an indication of degradation of
the waters.
It is probable that Lightner Creek has an adverse impact on the
Animas River's water quality for the following parameters; temperature,
total and fecal coliform concentrations, hardness, conductivity, turbi-
dity, sulfates, and nutrients. The 1974 special study indicates that
the degraded quality of Lightner Creek could probably be linked to the
nine dischargers located on the creek.
Hennosa Creek
Only one sample of Hermosa Creek water was taken by the Colorado
Department of Health. These data are presented in Table 9. A single
sample at a single location yields insufficient data for valid water
quality evaluation. However, the creek was not in compliance with
temperature standards during the 1974 monitoring. All other parameters
were within standard limits.
Junction Creek
No data were available for the evaluation of water quality of this
creek.
Florida River
Water quality of the Florida River was monitored for the Colorado
Department of Health in 1974. Two samples were taken at two locations
A-104
-------
TABLE 9
WATER QUALITY OATA
tCRMOSA CREEK
DATE
PAftAMFTER 7-29-74
T«np#r»tur« (*C)
22
Dissolved Oxygan, mg/1
7.7
pMf Units
8*6
Total Alkalinity, mg/1
60
Phanolphtalaln Alkalinity, mg/1
9
Total H«rdn«ss( mg/i
184
Calcium Hardn«ss, ng/l
132
Magna*lua Hardn«ss, mg/
8.0
Total Solids, mg/1
261
Total Olssolvad Solids, mg/1
274
Conductivity u Mhos
370
Sodium, mg/1
4
ChlorIda, mg/1
8
Sulfatas, mg/1
111
Turbid Ity mj
4
Nitrate, mg/1
0
NltrIta, mg/1
0
tanonia, mg/1
0
Ortho Phosohata «g/l
0
Arsanlc «g/1
0
Cadlum mg/1
0
Coppar mg/1
0
Iron mg/1
0
Laod ag/1
0
Zinc mg/1
0.05
A-105
-------
over a period of two months. The results of the monitoring are present-
ed in Table 10. Data are insufficient to draw conclusions, but some in-
ferences can be made when comparing Florida River water quality with
that of the Animas River at station 66.
1. Temperature of the Florida River is occasionally in
violation of the State standard. This might affect the
Animas River if the violations are frequent, although
causes are probably natural.
2. The DO concentration is well above the standard, and the
oxygen demand depresses the dissolved oxygen concentra-
tion less than ten percent below saturation. This oxy-
gen demand value is less than that found in the Animas
River above and below the confluence.
3. The pH of the Florida River is similar to that of the
Animas River and is in compliance with water quality
standards.
4. Total alkalinity of the Florida River is approximately
twice that of the Animas River.
5. Hardness of the Florida River is generally less than
that of the Animas River.
6. Solids concentrations appear to be less in the Florida
River than in the Animas River.
A-106
-------
TABLE 10
WATER QUALITY DATA
FLORIDA RIV&
Dat»
PARAMETER
STATION i.d.
7-25-74
9-12-74
Tamparatura, "C
F-1
21
17

F-2
20
16
Dlssolvad Oxygan, ag/l
F-l
8.4
9.6

F-2
9.3
9.0
pft. Units
F-l
8.7
8.3

F-2
8.3
8.1
Total Alkalinity, mg/1
F-l
180
200

F-2
232
248
Phanolphthalaln
F-l
12
0
AlkalInlty, ng/1
F-2
0
0
Total Nardnau, ag/l
F-l
160
240

F-2
220
296
Calclun Hardnau, ag/1
F-l
124
188

F-2
160
276
Magnaslum Hardnaas, ng/t
F-l
7.0
13.0

F-2
13.0
3.0
Total Solid*, ag/l
F-l
337

F-2
286

Total Olsaolvad Sol Ids, ag/1
F-l
249
290

F-2
282
290
Conductivity, u utos
F-l
383
300

F-2
493
300
Sodlua, ag/1
F-l
28
43

F-2
IS
16
Chlorlda, mg/1
F-l
34
20

F-2
14
6
Sulfataa, ag/1
F-l
29
33

F-2
33
23
Turtldlty, FTU
F-l
33
1.4

F-2
3
0.7
Nltrata, ag/1
F-l
0

F-2
0

Nltrlta, «g/1
F-l
0
0

F-2
0
0
A—on la, ag/1
F-l
0.3
0.7

F-2
0
0.4
Ortho Phoiphata, ag/l
F-l
0

F-2
0

A-107
-------
7. Sodium and chloride concentrations are higher in the
Florida River than in the Animas River, but sulfate
concentrations are lower. Sodium and chloride
concentrations are not increased enough to be valid
indicators of measurable wastewater discharges,
(Reference 16).
8. Turbidity, nitrate, and nitrite concentrations are lower
in the Florida River than in the Animas River, but
ammonia concentrations tend to be slightly higher.
The limited data on the Florida River indicate that temperature,
alkalinity, sodium, chlorides, and possibly ammonia may be contributing
to water quality problems in the Animas River.
Dischargers
There are 24 potential point source dischargers in the Study Area,
(Reference 12). Approximate locations of the discharge points are pre-
sented in Figure 8. Discharge rates and treatment types are listed in
Table 11. Ten sources discharge directly into the Animas River, nine
sources discharge into Lightner Creek, Hermosa Creek has two dis-
chargers, two sources discharge into Wilson Gulch, and one source dis-
charges into Junction Creek.
The largest discharger in the region is the city of Durango
municipal treatment facility. Self-reporting data from this treatment
facility are available from EPA and the Colorado Department of Health.
These data indicate that only small amounts, if any, of oil and grease
are present in the effluent. BOD is removed at a high percentage during
treatment, and total suspended solids are low. Occasionally pH in-
creases, but it is usually in compliance with standards. Fecal coliform
A-108
-------
POINT SOURCE DISCHARGERS
in the STUDY AREA
H«v 590
J
OUftANGO
I
-------
TABU II
ANIMAS RIVER DRAINAGE POINT SOURCE DISCHARGE INVENTORY*
Olschorge
Facility Ham* Type of Treatment Receiving Stream Permit
Ponderosa KOA
Campground
lonely TrolIs
Trading Post A
Restaurant
Whispering Pines
Traller Park
Bear llotlow
Campground
ttormosa Moodows
Camper Park
Lone Pine MobIle
Home Park
Mar ymac Mob 11 e
Home Park
Junction Creek
Tral ler Park
Durango Fish
Itatchery
Llghtner Creek
Safari Camp
Ram*da Camp
Inn
llghtner Creek
Mobile Home Park
Twin Buttes Flsti
Pond A Metchery
Four Winds
Motel
Per Ins Peak
Mobile Park
Extended Aeration
Package Plant
Extended Aeration
Package Plant
Non-dlscharglng
lagoon
Non-dIschargIng
Lagoon
Extended Aeration
Package Plant
Extended Aeration
Package Plant
Extended Aeration
Package Plant
SettlIng Basin
Cxtended Aeration
Package Plant
Extended Aeration
Package Plant
Extended Aeration
to Lagoon
SettlIng Ponds
3 Septic Tanks
with lagoon
tlome Made
Aeration System
Animas River
Animas River
Animas River
Heratosa Creek
Hermosa Creek
Animas River
Animas River
Junction Creek
Animas River
tlghtner Creek
tlghtner Creek
tlghtner Creek
tlghtner Creek
Llghtner Creek
Llghtner Creek
Applled
No
No
Applled
Applled
CO-00227W
CO-022746
C0-000028I
Applled
Applled
No
No
Applled
CO-0022 T05
Discharge Rate or
Treatment Capacity
to P.E. (seasonal)
Apprax. 200 P.E. (Discharge
to meadow above river)
50 P.E. (seasonal)
100 P.E,
150 P.E.
150 P.E.
50 P.E.
1.9 MOD
150 P.E. (seasonal)
50 P.E. (seasonal)
50
100 P.E. (seasonal)
to P.E.
-------
TABLE 11 (Continued)
facility Nam Type ol Treatment Receiving Stream
Discharge
Penal t
Discharge Rate or
Treatment Capacity
Durango Inn
Shakey's Pizza
Par lor
Cottonwood
Camper Park
City ol Durango
Extended Aeration
Package Plant
Extended Aeration
to Lagoon
Cvtended Aeration
Package Plant
TrlcklIng FlIter
Plant
Llghtner Creek
Llghtner Creek
Llghtner Creek
Animas Rlvar
Mo
Ho
Applled
Appro*. 100 P.E.
Appro*. 60 P.E.
100 P.E. (seasonal)
CO-OO24O02 16, 000 P.E.
San Juan
Lumber Co.
Basin Packing
Company
Plnon Acres
K0A Campground
Non-dlschargIng
Lagoon
Aerated Basin
to lagoon
Lagoon
Animas River
Animas River
Wilson Gulch
Applled
No
Appro*. 0,000 to
10,000 gpd
90 P.E. (seasonal)
Grandview Hotel
Extended Aeration
Package Plant
Chevron Station 4 Extended Aeration
Branding Iron Package Plant
Rastaurant
Wilson Gulch
Animas River
No
120 P.E.
40 P.E.
P.f. ¦ Population Equivalent
-------
concentrations vary considerably, from 1/100 ml to 10,000/100 ml, but
are generally moderate to low. The effluent fecal coliform concentra-
tion is much lower than that found downstream at station 66. In general,
the effluent is of relatively good quality, and probably has no major
adverse affects on the Animas River.
The other direct dischargers into the Animas River are considerably
smaller than the municipal treatment plant. Waste water quality data
from these nine sources are currently not available. It is possible
that the combined affect of these nine dischargers is significant.
Data for discharges into Lightner Creek are not available. It was
determined in a Colorado Department of Health study (Reference 13) that
discharges into Lightner Creek were having negative impacts on this
stream's quality. Lightner Creek, in turn, is a probable source of
degradation to the Animas River.
Potential point source discharges into Hermosa Creek use non-
discharging lagoons for waste treatment; therefore, impacts to this
stream from point source discharges are supposed to be eliminated.
A- 112
-------
State sampling data reveal that the Junction Creek Trailer Park
discharges wastewater which is excessively high in fecal coliforms to
Junction Creek. The effluent quality recorded from four recent sam-
plings is presented in Table 12. Although the flow from the trailer
park is small, the fecal coliform content of the wastewater probably
causes degradation of Junction Creek. This degradation may reach the
Animas River.
GROUNDWATER QUALITY
The State of Colorado has established standards of quality for
groundwater which is to be used as a domestic water supply, (Reference
18). The state recognizes two categories of domestic water supply
groundwater: 1) waters which are not specifically classified for
domestic use, or which have qualities not considered suitable for
domestic use but which may be suitable after special treatment, and 2)
uncontaminated groundwater which will meet drinking water regulations
without treatment. The state requires all domestic water supplies be
disinfected unless a waiver has been obtained.
Drinking water standards of the State of Colorado match those set
forth by the Federal Government. The standards relevant to groundwater
data for the Study Area are presented in Table 13 (References 19, 20, 21)
Data Sources
Groundwater data of the Study Area is sparse and incomplete.
Information sources for groundwater include the United States Geological
Survey (USGS), the Colorado Department of Waters Resources, and EPA
STORET data.
A-H3
-------
TABLE 12
JUNCTION CREEK TRAILER PARK
DISCHARGE DATA
OATE MONITORED
4/27 2/16 4/12 4/19 5/4 10/18 5/24 7/18 6/3 8/8 8/24 4/10
76 77 77 77 77 77 78 78 78 78 78 79
Temperature, 'F
pH, Units
Dissolved OKyg«n, «g/l
Chlorine Residual, ag/l
BOO, mg/1
Oil and Gr«ss«, *g/l
Suspended solids, mg/l

36.0
46.0
53.0
33.0
54.0
64.4
73.4
69.8
64.4
64.4
41.0
7. J
7.6

7.1
7.2
6.6
7.4
7.5

6.6
7.2
7.9
3.6
4.6
3.0
5.1
1.0
3.6
4.9
3.7
3.0
8.4
0.0
0.0
0.0
0.0
0.0

0.0
0.0
0.0

0.0
0.0
161.0
50.0
97.0
23.0
212.0
15.0
230.0
19.0
26.0
9.0
13.0
16.0
10.6
<10.0
16.0
0.7
7.t
<10.0
<10.0
<10.0
<10.0
<10.0
<1.0
<10,0
114.0

141.0
120.0
140.0
14.0
31.0
30.0
40.0

43.0
310.0
4,500 59,000 550,000 1701000 430,000 3,<00 130,000 2,300,000 110,000 4,000 31,000 230,000
-------
TABLE 13
STANDARDS FOR DOMESTIC GROUNDWATER SUPPLY
Parameter
Arsenic
Chloride
Fluoride
Iron
Manganese
Nitrate
pH
Phosphate
Selenium
Limit
0.05 mg/1
250 mg/1
1.4-2.A mg/1*
0.3 mg/1
0.05 mg/1
10 mg/1
509
No recommendation
0.01 mg/1
* Limit varies with temperature of water
A-H5
-------
The USGS data provided a description of the general characteristics of
various aquifers and general groundwater availability. No unique
groundwater quality data are available from this source (Reference 22).
The Colorado Department of Water Resources data consisted of wells
in the Study Area, (Reference 23 ). Most wells of the area were identi-
fied, and data such as well yield, well depth, and water level at the
time of drilling were given.
The EPA STORET data were the most useful for groundwater quality
evaluation, (Reference 24-). Detailed data are presented for twenty-two
different wells in the area. These data, however, cannot be considered
comprehensive because only one sample was taken at each well, and most
of the data is somewhat dated (1974 or 1975). In addition, data are
concentrated in specific areas of the Study Area and are sparse to
nonexistent in other areas. Florida Mesa contains approximately sixty-
three percent of the wells sampled, while the Florida River area and the
area immediately east of the city of Durango contain another twenty-two
percent. No data are available for the Animas Valley near Hermosa nor
for the area along the Animas River south of Durango.
Groundwater Data Evaluation
The EPA STORET data include groundwater quality information for
twenty-seven wells in the Study Area. Specifics about each well are
presented in Table 14. Well depth and water level at the time of
sampling are noted, along with approximate well yield. This latter
characteristic is from the Colorado Department of Water Resources data
and was not available for every well on the EPA STORET list. The
monitored water quality for each well is presented in Table 15.
A- 116
-------

TABLE
14

STUDY
AREA WELL
INFORMATION

I.D.
Owner
Yield
Depth
Water Level
Aquifer

(GPM
(Ft.)
(Ft.)

1.
Simon
10
137
99.7
Alluvium
2.
Wuest
-
180
55.85
Animas
3.
Fassett
-
240
46.84
Animas
4.
Colescott
20
90
55
Unknown
5.
Baker
15.0
83
57
Unknown
6.
Craig
5.0
60
51.18
Alluvium
7.
Unknown
-
201
45.42
Unknown
8.
Butler
-
200
38.02
Unknown
9.
Butler
-
300
46.62
Animas
10.
Decker
-
304
100.44
Animas
11.
Belger
4.0
114
30.72
Alluvium
12.
Queen
5.0
234
95
Unknown
13.
Cooper
-
49
37
Alluvium
14.
Barry
-
63
19.72
Unknown
15.
Cudiff
-
31
19.76
Alluvium
16.
Miller
30.0
140
61.61
Animas
17.
MacClean
-
80
-
Animas
18.
Cushing
-
180
-
Animas
19.
Palmer
10
110
95
Unknown
20.
Snider
5.0
105
62.37
Mancos
21.
Connor
10
57
47
Alluvium
22.
Hightower
-
102
19.88
Menefee
23.
Schriner
15
75
38.39
Alluvium
24.
Axtman
5
103
80.75
Mancos
25.
Balliger
-
115
69.73
Morrison
26.
Repert
30
105
69.79
Alluvium
27.
Haja
-
152
84.64
Morrison
A-117
-------
TABLE 15
GROUNDWATER QUALITY DATA
Well Identification^

1
2
3
4
5
6
Temperature °C
11.5
6.99
10.25
12.00
5.99
4.0
Conductivity, >imhos
459.99
569.99
712.50
649.99
599.99
874.99
Alkalinity mg/1
223.00
293.00
21.90
310.00
285.00
354.00

231.90
288.6
195.3
274.6
316.69
407.60
Nitrate & Nitrite, mg/1
1.86
9.299
15.5
3.72
8.68
3.10
Ortho Phosphate, mg/1
0.00
0.00
0.00
0.00
0.00
0.00
Dissolved Phosphorus, mg/1

Hardness mg/1
235.0
315.00
285.00
280.00
295.00
464.99
Noncarbonate Hardness, mg/1
. 44.99
77.99
111.0
0.00
35.00
131.00
Dissolved Calcium, mg/1
78.16
100.20
84.17
92.18
76.15
98.199
Dissolved Magnesium, mg/1
9.73
15.81
18.24
12.16
25.54
53.499
Dissolved Sodium mg/1
12.87
35.63
43.68
33.57
27.13
23.45
SAR
0.40
0.90
1.10
0.87
0.70
0.50
Dissolved Potassium, mg/1
1.17
1.560
0.78
1.17
0.78
1.17
Chloride, mg/1
14.18
33.69
85.09
10.64
24.82
30.139
Sulfate, mg/1
34.1
44.19
51.39
44.67
30.26
134.50
Dissolved Fluoride, mg/1
0.17
0.10
0.44
0.12
0.13
0.13
Dissolved Silica, mg/1

Dissolved Arsenic,>g/1
0.00
0.00
0.00
0.00
0.00
0.00
Dissolved Iron.^Kg/l
0.00
0.00
0.00
0.00
0.00
0.00
Dissolved Manganese g/1

Dissolved Selenium,^, g/1
TDS, mg/1
2.00
4.00
160.00
2.00
3.00
9.99
295.00
435.00
455.99
389.00
358.0
612.99
pH, units 7.20 7.599 7.899 7.299 6.99
Boron, >>-g/l 0.00 0.00 0.00 0.00 0.00 0.00
1 See Table 1A
A- 118
-------
TABLE 15 (continued)
GROUNDWATER QUALITY DATA
Well Identification
10
11
12
Temperature °C
Conductivity,^umhos
Alkalinity
Nitrate & Nitrite, mg/1
Ortho Phosphate, mg/1
Dissolved Phosphorus, mg/1
Hardness
Noncarbonate Hardness, mg/1
Dissolved Calcium, mg/1
Dissolved Magnesium, mg/1
Dissolved Sodium, mg/1
SAR
Dissolved Potassium,
mg/1
Chloride, mg/1
Sulfate, mg/1
Dissolved Fluoride, mg/1
Dissolved Silica, mg/1
Dissolved Arsenic, ^ug/1
Dissolved Iron,^.g/l
Dissolved Manganese t>u.g/l
Dissolved Selenium,
TDS, mg/1
pH, units
Boron,^u.g/1
14.00
12.00
16.00
9.99
9.99
14.5
535.0
313.00
849.49
479.99
459.99
649.99
227.0
133.00
199.00
239.00
228.0
243.00
277.00
154.00
192.00
291.00
249.00
255.7
0.79
0.130
0.25
0.45
1.86
0.62
0.06
0.03
0.02
0.06
0.01
0.00
0.02
0.01

0.02

180.00
28.00
30.0
200.0
195.0
59.99
0.00
0.00
0.00
0.00
0.00
0.00
59.00
0.699
9.99
62.99
70.14
20.04
7.8
0.999
1.20
9.99
0.49
2.43
46.00
60.99
167.00
34.00
29.43
128.7
1.50
5.00
13.00
1.10
1.0
7.23
0.8
0.50
0.30
1.6
0.78
0.78
21.0
15.00
64.99
12.0
3.55
50.35
22.0
58.99
65.99
24.0
38.89
33.61
0.90
1.60
8.79
0.699 0.23
2.41
10.00
2.80

16.0

1.00
0.99
7.99

0.00
4.00
30.00
99.99
0.00
49.99
0.00
0.00
30.00
20.00

0.00

3.0
0.00
0.00

0.99
2.00
308.0
178.00
405.99
367.0
293.0
356.0
7.8
8.79
9.30
7.49
7.39
8.49
6.00
5.99
0.00

0.00
399.00
See Table 14
A-119
-------
TABLE 15 (continued)
GROUNDWATER QUALITY DATA
Well Identification*

13
14
15
16
17
18
Temperature °C
7.49
13.0
11.00
5.5
6.0
17.00
Conductivity, ^wmhos
659.99
618.00
644.99
667.00
470.00
436.00
Alkalinity
278.00
273.00
310.00
353.00
254.00
199.00

331.29
333.00
324.59
430.00
310.00
243.00
Nitrate & Nitrite, mg/1
9.29
2.60
6.199
0.010
i 0.67
0.26
Ortho Phosphate, mg/1
0.03
0.18
0.02
0.00
0.00
0.00
Dissolved Phosphorus, mg/1

0.06

0.00
0.00
0.00
Hardness
300.00
270.00
305.00
13.0
50.00
200.0
Noncarbonate Hardness, mg/1
29.00
0.00
0.00
0.00
0.00
0.00
Dissolved Calcium, mg/1
100.2
91.00
108.20
4.3
19.00
64.00
Dissolved Magnesium, mg/1
12.16
10.00
8.51
0.5
0.70
9.10
Dissolved Sodium, mg/1
42.00
22.00
26.90
180.00
120.00
16.00
SAR
1.10
0.60
0.67
22.00
7.40
0.50
Dissolved Potassium, mg/1
1.17
0.80
0.78
0.40
0.50
0.40
Chloride, mg/1
24.82
16.00
14.18
14.00
10.00
9.70
Sulfate, mg/1
56.68
22.00
27.38
33.00
27.00
35.00
Dissolved Fluoride, mg/1
0.18
0.20
0.120
1.200
' 1.40
0.20
Dissolved Silica, mg/1

18.00

9.50
9.20
10.00
Dissolved Arsenic .^g/l
0.00
1.00
0.00
1.00
2.0

Dissolved Iron,^ug/l
0.00
20.00
0.00
20.00
40.00
30.00
Dissolved Manganese,>ug/l

0.00

0.00
0.00
20.00
Dissolved Selenium, ^g/1
2.00
1.00
0.999
0.00
0.00

TDS, mg/1
424.99
356.00
423.99
455.00
344.00
265.00
pH, units
7.09
7.1
6.89
8.0
7.7
7.4
Boron,^wg/1
0.00
30.00
0.00

10.00
^ See Table 14
A-120
-------
TABLE 15 (continued)
GROUNDWATER QUALITY DATA
Well Identification'"

19
20
21
22
23
Temperature °C
8.5
10.00
7.00
6.00
8.00
Conductivity >*.mhos
710.00
2,278.
348.00
1,060
5,630
Alkalinity
280.00
1,030
176.00
437.00
477.00

341.00
1,250
215.00
533.00
581.00
Nitrate & Nitrite, mb/1
1.10
0.01
0.15
0.280
23.00
Ortho Phosphate, mg/1
0.12
0.12
0.00
0.03
0.670
Dissolved Phosphorus, mg/1
0.04
0.04
0.00
0.010
0.22
Hardness
310.00
48.00
190.00
250.00
2,400
Noncarbonate Hardness, mg/1
32.00
0.00
12.00
0.00
1,900
Dissolved Calcium, mg/1
110.00
9.30
50.00
62.00
600.00
Dissolved magnesium, mg/1
8.90
6.10
10.00
23.00
220.00
Dissolved Sodium, mg/1
44.00
610.00
4.5
200.00
780.00
SAR
1.10
38.00
0.10
5.50
6.9
Dissolved Potassium, mg/1
0.90
2.00
1.14
2.8
11.00
Chloride, mg/1
7.60
130.00
1.8
15.00
1,400
Sulfate, mg/1
91.00
190.00
19.00
220.00
1,400
Dissolved Fluoride, mg/1
0.40
2.80
0.10
0.30
0.30
Dissolved Silica, mg/1
13.00
7.30
6.70
13.00
20.0
Dissolved Arsenic,>g/l
1.00
0.00
1.00
0.00
3.00
Dissolved IronJyag/l
20.00
40.00
20.00
1,500
60.00
Dissolved Manganese, >g/l
0.00
0.00
0.00
100.00
30.00
Dissolved Selenium, ^u.g/1
1.00
6.00
0.00
1.00
8.00
TDS, mg/1
449.00
1,570
209.00
811.00
4,820
pH, units

8.2
7.30
7.10
7.30
Boron, y.tg/1
* See Table 14
A-121
-------
TABLE 15 (continued)
GROUNDWATER QUALITY DATA
Well Identification1
24 25 26 27
Temperature °C
0.00
6.00
10.5
8.5
Conductivity /iinhos
932.00
370.00
552
550
Alkalinity
508.00
154.00
302
255

603.00
188.00
368
311
Nitrate & Nitrite, mg/1
0.10
0.140
0.14
0.02
Ortho Phosphate, mg/1
0.03
0.03
0.00
0.15
Dissolved Phosphorus, mg/1
0.01
0.01
0.00
0.05
Hardness
12.00
180.00
320
200
Noncarbonate Hardness, mg/1
0.00
28.00
15.00
0.00
Dissolved Calcium, mg/1
3.30
55.00
79.00
50.00
Dissolved Magnesium, mg/1
1.00
11.00
29.00
18.00
Dissolved Sodium, mg/1
250.00
6.4
13.00
30.00
SAR
31.00
0.2
0.30
0.90
Dissolved Potassium, mg/1
0.60
0.7
3.10
6.6
Chloride, mg/1
20.00
1.8
' 4.10
5.6
Sulfate, mg/1
34.00
43.00
37.00
15.00
Dissolved Fluoride, mg/1
1.10
0.20
0.10
0.6
Dissolved Silica, mg/1
7.60
5.30
13 .00
15.00
Dissolved Arsenic,^ug/1
0.00
0.00
1.00
14.00
Dissolved Iron,^ug/l
160.00
10.00
20.00
1,800
Dissolved Manganese,>ug/l
20.00
0.00
0.00
110.00
Dissolved Selenium,^ug/1
0.00
0.00
2.00
0.00
TDS, mg/1
623.00
217.00
360
296
pH, units
9.1
7.3
7.7

Boron, ^ug/1
0.8

1 See Table 14
A- 122
-------
Possible groundwater contamination from human activity is often
indicated by high concentrations of nitrogen oxides (NO^ and NO^) and by
concentrations of sodium and chloride in excess of those found in the
area or in the underlying geologic formations. Violations of standards
for any metal could also be an indication of man-induced contamination,
particularly if the metal is not native to the area or formation. No
concrete conclusions on groundwater in the Study Area can be drawn from
this one-sample data, but some generalizations will be made.
Lightner and Junction Creek Areas
Included in these areas are data from four wells: numbers 20, 21,
25, and 27. Review of the data from these wells indicates the
following:
1. Nitrate-nitrite concentrations are low for all wells.
2. Well 20 has one of the highest sodium concentrations of
any well in the entire Study Area. This might indicate
possible contamination. However, the Mancos aquifer
from which this well draws its water is typically a
sodium bicarbonate type, (Reference 22 ), so the excess
sodium could be from natural sources. The other wells
in this area do not draw from the Mancos formation, and
have low sodium concentrations.
3. Well 20 has one of the highest chloride concentrations
of any well in the entire Study Area. This might
indicate possible contamination. Again, the Mancos
aquifer is reported to be naturally high in chloride.
Further study may be warranted to determine if contam-
ination of the groundwater has actually occurred.
A-12 3
-------
Florida River Area
This section of the Study Area encompasses a small segment of the
Florida River and the area immediately east of Durange between the city
and the Florida River. Included in this area are six wells: numbers 18,
19, 22, 23, 24 and 26. Review of the data for these wells reveals the
following:
1. Well 23 has excessively high concentrations of
nitrate-nitrites, salt, and metal parameters. Either
this well is located atop a pocket of bad water or it is
polluted.
2. Waters from wells 18, 22, 24, and 26 show low nitrate-
nitrite concentrations. The nitrate-nitrite concentra-
tion of well 19 is somewhat higher, but is not in viola-
tion of the Public Health Standard. The higher nitrate-
nitrite concentration might be attributable to the
well's being rechanged by the Florida River, which has a
similar nitrogen content to that of well 19.
3. Wells 18, 19, 24, and 26 show low sodium concentrations.
Well 22 shows a higher sodium content, although it is
not in excess of the standard. This well is in the
Menefee aquifer, which is a sodium bicarbonate type;
thus, the water would naturally tend to have a rather
high sodium concentration.
4. Wells 18, 19, 22, and 26 show low chloride concentra-
ions.
A-L24
-------
5. Manganese and iron Public Health Standards are violated
in the water of well 22. This is not uncommon for water
of the Menefee aquifer.
6. Well 24 water shows a pH slightly in excess of the
Public Health Standard.
Florida Mesa Area
This section of the Study Area includes the Florida Mesa south and
west of Durango. Included in this section are seventeen wells, numbers
1 through 17. Since the wells in this area are so numerous, they will
be divided into three groups for discussion: (1) those wells drawing
water from the alluvial aquifer; (2) those wells drawing water from the
Animas aquifer; and (3) those wells for which the aquifer source is
unknown.
The group of wells drawing water from the alluvial aquifer include
wells 1, 6, 11, 13, and 15. The data for these wells indicate the
following:
1. Wells 1, 6, and 11 have nitrate-nitrite concentrations
that range from 1 mg/1 to A mg/1. Wells 13 and 15 have
higher nitrate-nitrite concentrations of 9 mg/1 and 6
mg/1, respectively. None of the concentrations exceeds
the Public Health Standards. These nitrogen data
indicate a natural nitrogen concentration in the aquifer
and perhaps, some contamination.
2. All data indicate that the waters of this group of wells
are relatively low in sodium.
3. All data indicate that the waters of this group of wells
are low in chloride.
A-125
-------
4. Data indicate that no violations of metal standards
occurred in the groundwater from this group of wells.
The group of wells drawing water from the Animas aquifer includes
wells numbered 2, 3, 9, 10, 16 and 17. The data for these wells reveal
the following:
1. Wells, 9, 10, 16, and 17 have low nitrate-nitrite con-
centrations. Wells 2 and 3, however, have much higher
nitrate-nitrite levels, with the concentration of well 3
violating the Public Health Standard. Wells 2 and 3 are
near each other, so the high nitrogen levels may be nat-
ural to the area, or may be indicative of contamination.
2. Water from wells 2, 3, and 10 show low sodium content.
Waters from wells 9, 16, and 17 show much higher sodium
concentrations. These wells are not in close proximity
to one another, and the Animas formation is not particu-
larly known for high sodium content. These high concen-
tration levels might be an indication of contamination.
3. Chloride is not excessive in the water of any of the
wells in this group.
4. The Public Health Standard for selenium is violated in
the water of well 2. No other metals standards are
violated in waters of any of the other wells in this
group.
The group of wells for which the aquifer source is unknown includes
wells numbered 4, 5, 7, 8, 12, and 14. Data for these wells show the
following:
A-126
-------
1. Water from wells in this group generally show a moderate
to low nitrate-nitrite concentration except well 5.
Well 5 has a high nitrate-nitrite level, but it was
still under Public Health Standards.
2. Water from wells in this group show a low sodium concen-
tration except well 12. Well 12 is in close proximity
to well 10 and is of similar depth. Well 10 does not
have a high sodium concentration; thus, there might be
possible contamination.
3. All water from wells in this group show moderate
chloride concentrations.
4. No metal standards are violated by the groundwater of
wells from this group.
SUPPLEMENTAL WATER QUALITY MONITORING PROGRAM
Because of the incomplete nature of the historical water quality
data base for the Durango 201/EIS Study Area, a water quality monitoring
program was developed and implemented in June 1979. Because the prin-
cipal type of wastewater treatment in the Study Area is the conventional
septic tank/absorption field, it was determined that the monitoring pro-
gram would have to occur during the high ground water period in order to
identify possible groundwater contamination from these systems. It was
recognized that identification of point specific sources of surface
pollution would not be possible, due to high runoff.
The monitoring program consisted of six surface water quality
stations (three located on the Animas River, and three on the Florida
River), nine groundwater stations in the Animas Valley, and three
springs on Florida Mesa. These monitoring stations are located in
Figure 9.
A-127
-------
Temperature, dissolved oxygen (DO), pH, and conductivity were
monitored at all surface water quality stations (excluding the springs)
at the time of sampling. Water samples were collected and analyzed for
the following parameters, using Standard Methods, by Four Corners
Environmental Research Institute under the direction of Ms. Doreen Mehs:
o
kjeldahl nitrogen
o
nitrate nitrogen (NO^ as N)
o
ammonia nitrogen (NH^ as N)
o
hardness
o
total dissolved solids (TDS)
o
total suspended solids (TSS)
0
bio-chemical oxygen demand (BOD)
0
chemical oxygen demand (COD)
o
orthophosphate
o
total phosphate
o
alkalinity
o
methyl blue active substances (MBAS)
o
total coliform
o
fecal coliform
Sampling techniques used in this study included a twenty-four hour
composite sampling at each of the six surface water stations, one grab
sample at each ground water and spring station, and one bacteriological
sample at all stations. All but one of the surface water
bacteriological samples were reported lost. Additional samples at five
surface water stations were collected on July 27, 1979 and analyzed.
Therefore, total and fecal coliform data for stations A-l, A-2, A-3,
F-2, and F-3 represent this later sampling.
Collection of groundwater samples was facilitated by assistance
from the Soil Conservation Service (SCS). Core holes six feet deep were
drilled at selected locations in the Animas Valley. These monitoring
holes were placed within highway right-of-ways. Permits to drill were
received from the Colorado Highway Department in Durango.
A-128
-------
Surface Water Monitoring
The Animas and Florida River were sampled on June 16 and 17, 1979.
Three stations on each river were selected as monitoring sites. Each
station was sampled once every six hours to form a composite sample over
a twenty-four-hour period. This procedure was used because many water
quality parameters vary within a normal twenty-four-hour day. Grab
samples for analyses were collected by standard procedures and placed in
noncontaminated containers. Bacterial samples were taken at each
station during the second six-hour period. This period was selected
because a peak in wastewater discharge generally occurs during the
morning hours. If bacteria from septic tanks were entering the stream
segments, it is likely that bacterial influence would be most
significant during this sampling period.
Field monitored data are presented in Table 16. The chemical and
bacterial analyses are presented in Table 17. Values for temperature,
DO, and pH are within the standards limitations. Temperatures tend to
increase as the waters flow downstream. This is probably a natural
occurrence resulting from runoff from agricultural lands and heating by
sunlight. In general, the DO values decrease downstream, but no con-
sistency is observed during every sampling period. There is a general
rise in pH from the second to the third station on both rivers.
Biochemical oxygen demand increases downstream, from 0.6 to 1.4
mg/1, and from 1.8 to 2.4 mg/1 in the Florida and Animas Rivers, res-
pectively. This parameter indicates the amount of oxygen needed to
stabilize biodegradable organic materials. An increase in BOD indicates
an increased presence of oxygen demanding material, including organic
pollutants, in the stream segment.
A-129
-------
TABLE 16
FIELD MONITORED PARAMETERS SURFACE WATER QUALITY
pH
Temp. DO Standard Conductivity
Station No.* Date Time (°C) (°F) (mg/1) Units ( mhos)
F-l
6/16/79
6:50
7.01
(44.62)
9.1
7.91
500
F-2
6/16/79
7:40
7.18
(44.92)
7.9
6.94
3,500
F-3
6/16/79
8:15
7.45
(45.41)
7.80
7.02
1,000
A-l
6/16/79
9:25
4.68
(40.42)
8.50
7.05
500
A-2
6/16/79
9:45
5.63
(42.13)
7.80
7.18
750
A-3
6/16/79
10:45
7.40
(45.32)
6.70
7.45
900
F-l
6/16/79
14:05
7.38
(45.28)
6.55
7.35
1,000
F-2
6/16/79
14:30
9.64
(49.35)
6.67
7.34
1,300
F-3
6/16/79
15:05
10.80
(51.44)
7.87
7.45
1,200
A-l
6/16/79
16:05
9.18
(48.52)
7.60
7.38
100
A-2
6/16/79
16:30
9.78
(49.60)
6.80
7.08
1,100
A-3
6/16/79
16:55
9.40
(48.92)
8.26
7.39
1,200
F-l
6/16/79
19:00
6.98
(44.56)
7.47
7.12
1,000
F-2
6/16/79
19:25
8.07
(46.53)
7.80
6.95
1,100
F-3
6/16/79
19:45
8.76
(47.77)
7.90
6.99
1,200
A-l
6/16/79
20:30
9.59
(49.26)
8.10
7.19
700
A-2
6/16/79
20:45
10.13
(50.23)
7.35
6.66
1,000
A-3
6/16/79
21:25
9.95
(49.91)
7.10
7.11
1,000
F-l
6/16/79
22:15
7.03
(44.65)
8.60
6.40
800
F-2
6/16/79
22.35
7.18
(44.92)
8.00
6.82
900
F-3
6/16/79
23.00
7.44
(45.39)
8.02
7.15
1,000
A-l
6/16/79
23:45
7.37
(45 .27)
8.44
6.15
500
A-2
6/17/79
0:05
8.26
(46.87)
7.50
7.34
800
A-3
6/17/79
0:30
10.06
(50.11)
7.10
7.29
900
~Locations of stations are shown on Figure Al.
A-130
-------
TABU 17
RESULTS Of CHEMICAL AND BACTERIAL ANALYSES ON
StflFACE WATERS OF THE ANIMAS AM) FLORIDA RIVERS

AlfcalInlty

KJeldahl

Ortho-
Total
¦gCsCO /I

Total"
Focal"*

NO^ as N
»4 as
N Hardness
TDS
TSS
BOO
Nltrogan
COO
phosphate Phospate
to »et ny1

Col 1 form
Co11f OTM

Sample*
CpprfO
(pp«*)
fug CaC03/l)
<«g/n
(ng/1)
<«g/1>
(ppiiN)

(ppa P)
(ppm P)
orange
MBAS
(MPN)
(WN)
Sanpl.
F-l
0.23
<.01
86
77
17
0.6
1.0
60.6 0.023
0.030
313
<0.1
<1/100 Ml
t
8
N
V
F-l
F-2
0.24
<•01
92
91
13
2.1
0.9
4.a*** 0.045
0.060
340
iP. <
8/100 *1
4/100 al
F-2
F-3
0. 20
0.01
90
110
5
U4
0.5
35. J
0.033
0.063
353
<0.\
17/100 Ml
22/100 .1
F-3
A-l
0.28
<•01
57
100
1
(.8
2,2
28.5
0.045
0.072
154
<0.1
8/100 Ml
2/100 ml
A-l
A-2
0.25
<.01
68
140
<1
1.0
<0.5
33.5
0.065
0.270
205
JC0. 1
33/100 Ml
7/100 .1
A-2
A-3
0.25
<.01
75
95
35
2.4
1.5
23.1
0. 145
0.255
277
_
-------
Orthophosphate and total phosphate also increase in concentration
downstream. The Florida River shows an increase in orthophosphate
between stations F-l and F-2, and a continual downstream increase in
total phosphate. The Animas River shows a continual increase of both
parameters, with the values at station A-3 three times those at station
A-l. Increases in these nutrient parameters indicate a potential in-
crease in algal growth in the waters.
Total dissolved solids continually increase downstream in the
Florida River but increase only from station A-l to station A-2 in the
Animas River. Total suspended solids increase substantially from
station A-2 to station A-3 in the Animas River. No such increase occurs
in the Florida River.
Total and fecal colifonn samples for all but station F-l were
collected on July 27, 1979, a period of lower flow than the original
monitoring period. This lower flow condition should serve to accentuate
any coliform problems which might exist. It can be seen from Table 17
that there is a general trend in both rivers for total and fecal coli-
form counts to increase downstream. However, the increases are not
significant and the values remain well below water quality standards.
Hardness and alkalinity show downstream increases in both rivers,
and the other chemical parameters; NO^ as N, NH^ as N, COD, Kjeldahl
nitrogen, and MBAS generally show decreases downstream.
Groundwater and Spring Water Monitoring
Groundwater was monitored in the Animas River valley and spring
water was monitored on Florida Mesa. Grab samples were collected June
16 and 17, 1979. Nine groundwater sites in the Animas River valley and
three springs on Florida Mesa were selected as sample locations.
A-132
-------
The nine sites in the Animas River valley included three near
Hermosa (HER-GW-N, HER-GW-C, HER-GW-S), three near Trimble Lane
(TL-GW-N, TL-GW-C, TL-GW-S), and three in the south Animas valley
(SA-GW-N, SA-GW-C, SA-GW-S). Station HER-GW-N did not yield a sample
due to a lack of water; therefore, only eight samples were collected.
The ground water sites were selected using the following criteria:
the locations must be accessible by truck so that SCS drilling equipment
could have access; the sites must be located near possible pollution
sources, i.e., septic tanks, wastewater lagoons, etc.; and the sites
must be located with the direction of groundwater movement known, down-
stream of potential pollution sources. Accessibility by truck, as well
as lack of access to private property, inhibited choices for sample
locations. The sites chosen were felt to be adequate but not optimum.
The springs were monitored as possible indicators of subsurface
contamination on Florida Mesa because these springs are fed by Florida
Mesa ground water.
The results of the analyses of the grab samples are presented in
Table 18. Total coliform counts of the ground and spring waters vary
from point to point, with the highest count, 490/100 ml, being found in
the Animas Valley near Hermosa (HER-GW-C). Two points near Trimble Lane
show the next highest counts. The fecal coliform count, which can
indicate bacterial contamination from septic tanks, is less than 20/100
ml at all points.
The presence of fecal coliform does indicate that contamination
though currently low, is occurring. However, the source may not be
specifically identified since fecal coliform contamination may originate
from animal concentration areas as well as from domestic wastewater.
During the groundwater monitoring very few animals were observed in the
areas believed to be above the ground water stream.
A-133
-------
TABl£ 18
RESULTS OF CHEMICAL AND BACTERIAL ANALYSES ON
GROUNDWATER AT© SPRING WATER WAB SAMPLES

Depth

Ortho-
Total

Total

fecal

to water
NOj as N
TOS
TSS
phosphate
Phosphate
Col 1 form
Col 1 for*

Saaple*
(It)
(ppnN)
<»g/1>

(ppi P)
-------
The methylene blue active substance test which indicates the
presence of foaming agents (such as detergents) is less than or equal to
0.2 for all locations except at SA-GW-S which had a value of 0.3. This
is a possible indication of septic tank influence; however, the value is
within the possible range of laboratory error.
Values for nutrient parameters, N0^ as N, orthophosphate, and total
phosphate, vary widely among the sampling locations. The spring waters
show low orthophosphate and total phosphate values, but relatively high
N03-N values occur at two locations, FM-GW-1 and FM-GW-2. Samples from
the Hermosa area have moderate to low NO^-N values, but high orthophos-
phate and total phosphate values. Trimble Lane groundwaters show low
NO^-N values; however the highest orthophosphate and total phosphate
values occur in this area. Groundwaters from the south Animas valley
locations show low values for all these parameters, except station
SA-GW-N, which has a NO^-N value of 1.96 ppm, the highest of any of the
groundwater sampling locations. The wide variation of these parameters
among stations could be naturally occurring or could indicate pollution
problems.
Total dissolved solids and total suspended solids are shown in the
table as having high values. The high values for TSS are probably a
result of boring hole cave-ins and/or disturbances of the soils con-
taining the groundwaters and spring waters during sampling. TDS values
indicate particularly high dissolved solids near Trimble Lane. This is
probably a result of geologic formations influencing quality.
Conclusions
The data from the surface water monitoring program of the Animas
and Florida Rivers indicate the following:
1. No EPA or Colorado State water quality standards are
violated in this group of data. This is potentially a
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consequence of the high runoff flows which provide a
greater than normal dilution of pollutants in the
rivers.
2. BOD of both rivers increases as the waters flow down-
stream, indicating degradation is occurring. This may
be a function of high volumes of nonpoint source pollu-
tants carried by spring runoff.
3. Orthophosphate and total phosphate generally increase in
both rivers as the waters flow downstream, indicating
some nutrient loadings.
A. Some increases in TDS and TSS are evident, but are not
continuous, downstream along both rivers.
5. Values of other parameters, including nitrogen and MBAS,
indicate no particular problems exist for these param-
eters .
The data pertaining to groundwater and spring water, although not
comprehensive, indicate the following:
1. No excessive coliform counts, total or fecal, were found
at any sample. Some fecal contamination appears to have
occurred but the source is currently unknown.
2. The SA-GW-S site shows the presence of foaming agent,
indicating possible influence of septic tanks, but it is
not believed to be excessive.
3. Samples showed wide ranges in nutrient concentrations,
which could indicate natural variation of these param-
eters or possible pollution problems in some areas.
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POPULATION, SOCIOECONOMIC FACTORS, LAND USE
It is the policy of EPA that population forecasts used for purposes
of planning local and regional wastewater facilities be consistent with
adopted state forecasts. The state forecasts are required to be consis-
tent with national forecasts by state prepared by the U.S. Department of
Commerce, Bureau of Economic Analysis for EPA in 1978.
It is also the policy of EPA that wastewater facilities plans be
consistent with local land use plans and policies. Both the requirement
of consistency in population forecasts and the requirement of consisten-
cy in planning are intended to avoid wasteful expenditures of public
funds which might result from oversizing or from construction of waste-
water facilities in areas not planned for or suitable for development.
This section presents data on recent and future growth in La Plata
County and discusses available population forecasts and the status of
local land use planning In order to assure that EPA policies are being
observed in those areas in which project funding is being sought.
Existing Conditions
Recent Growth Trends
La Plata County with a 1978 population of over 25,000, has grown
steadily during the decade of the 1970's, showing an eight-year popula-
tion increase of thirty-one percent. Host of this growth took place
outside the city of Durango, which grew only nine percent over the same
period. (Data are summarized in Table 19). These statistics reflect the
number of permanent residents. The overall level of population is
higher because of part-time residents; people with summer or winter
homes in the area, but primary residences elsewhere, and tourists.
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TABLE 19
RECENT POPULATION GROWTH IN LA PLATA COUNTY AND DURANGO
Growth,
1970 1978 1970 to 1980
La Plata County 19,199 25,101 31%
Durango City 10,333 11,245 9Z
Durango as Proportion of
La Plata County 54% 452! -
Source: U.S. Census of Population, 1970, and U.S. Census of Population,
1978 (both taken in April).
Sources of Past Growth
The growth of La Plata County mirrors the rapid growth being expe-
rienced throughout the Rocky Mountain states, the nation's fastest
growing region. A variety of local factors currently encourage growth
in the mountain states. Examples are industrial development in Idaho,
energy resources development in Wyoming, and metropolitan growth rela-
ting to retirement migration and general economic expansion of the "sun
belt" states in Arizona and New Mexico.
Colorado has participated in the growth resulting from each of
these factors, and southwestern Colorado (the counties of Archuleta,
Dolores, La Plata, Montezuma and San Juan) has been growing at a
slightly more rapid rate than the rest of the state (see Table 20).
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TABLE 20
RECENT POPULATION GROWTH IN THE STATE OF COLORADO
PLANNING AND MANAGEMENT REGION 9
1980
(midrange Growth,
1970 estimate) 1970 to 1980
Colorado 2,209,597 2,791,325 26%
Region 9 37,356 50,256 351
Archuleta County 2,700 3,900 44%
Dolores County 1,600 1,600 0
La Plata County 19,200 28,000 46%
Montezuma County 13,000 15,900 22%
San Juan County 800 900 13%
Detail does not add to total due to independent rounding.
Source: Colorado Division of Plkanning, Department of Local Affairs,
Demographic Section: "Population Estimates and Projections,"
August 1979
Tourism. Regional economic data do not suggest a clear-cut
explanation for the area's growth, but certainly tourism is an important
factor. In the Durango area in particular, tourism appears to be the
principal economic force in the community, with sixty-six percent of
jobs (exclusive of agriculture, government and self-employed) in retail
and service positions, the key tourist-support sectors, as compared with
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sixty-eight percent in the State as a whole (U.S. Department of Com-
merce, Bureau of the Census, 1976). An estimate of overnight tourism
during the peak summer months was provided in. a 1977 report by
Henningson, Durham & Richardson; 5,000 overnighters in Durango.
There are important tourist-oriented activities in the greater
Durango area both in summer and winter. The Denver and Rio Grande
Western Railway, a narrow-gauge railway between Durango and Silverton,
designated a National Historic Landmark, is an important attraction for
tourists during the summer. The fact that the excursion requires a full
day means that visitors typically stay in Durango area at least one
night, thereby supporting a large number of lodging and dining places.
The area is close to the Mesa Verde National Park with its ruins of
ancient cliff dwellings. Skiing brings many visitors into the area, and
there are a number of alpine ski areas readily accessible from Durango:
Purgatory, Telluride, Wolf Creek, Hesperus and Stoner. Although many
skiers find lodging at the ski areas, others stay in Durango or visit
the city while in the area. Hunting, fishing, and boating opportunities
abound. Both in winter and in summer, travel packages which include
Durango accommodations are offered by a number of tour operators. Table
21 summarizes important visitor statistics.
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TABLE 21
REPRESENTATIVE VISITOR STATISTICS
1970 1978
Denver and Rio Grande Western Railroad
Passengers 90,000 120,000
Mesa Verde National Park Visitors 525,000 654,000
Purgatory Ski Area Skier Days 64,000 258,493
La Plata Field Passenger Movements 53,000 102,395
(1975)
Source: Durango Chamber of Commerce: "Economic Trends," 1979
Part-time residents. Local observers indicate that the Durango
area is increasingly attracting new part-time residents, largely from
other states, who establish second homes in La Plata County. The
county's attraction for these out-of-state buyers arises from a combina-
tion of factors. Because it is an important tourist area in this sec-
tion of Colorado, many out-of-state travelers have had an opportunity to
visit it. This is less true of some of the more out-of-the-way mountain
communities such as Blake City and Silverton. It is unquestionably an
area of great scenic and natural beauty, still uncrowded and with clean
air and lovely mountain vistas. Agricultural potential and numerous
outdoor activities are added attractions. Further, Durango is a town of
sufficient size to provide stores, services, medical facilities and
educational institutions - important assets particularly for those who
plan eventually to retire in the area.
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In-migrants. Many local observers comment that Durango has no real
economic base. Reportedly individuals move in from out of state without
jobs, supporting themselves on savings until they find some way of
making a livelihood, which often results in their establishing their own
retail or service businesses. For this reason, out-of-town financial
assets are commonly reckoned among the principal economic resources of
the region. It also seems likely that the proportion of self-employed
may be higher in the Durango area than would generally be true else-
where. This supposition is supported by 1976 data showing that the
number of business establishments per 100 residents is about thirty
percent higher in La Plata County than in Colorado as a whole.
Growth and the Housing Supply
The influx of new people has probably been an important factor
contributing to rapidly increasing housing prices in the area. There is
general agreement that local housing prices have risen rapidly and
currently well exceed the affordability levels of most local households.
This situation explains in part the rapid increase in the number of
mobile homes in the county over the last few years (from thirteen per-
cent of housing starts in 1975 to thirity-five percent in 1978 and 1979)
(PBR, 1980).
At present, there is generally a low volume of construction activi-
ty: few builders operate at a scale in excess of ten single-family units
a year. Lack of scale economies combined with conservative lending
policies of local financial institutions (which affect both construction
companies and individual homebuilders) have certainly been factors in
high housing costs. The fact that income levels of Durango's permanent
residents are generally lower than in the state as a whole exacerbates
the problem of housing affordability. However, in the entire region of
which Durango is a part, housing costs are reported to be generally
high; La Plata County is not exceptional in this respect. Some local
observers believe high housing costs to be a major impediment to in—
migration into the region (Four Corners, 1978, p. 111-24).
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Future Growth
La Plata County and Durango are expected to continue to grow in the
future: on that point there is consensus. As to the extent of growth
and the importance of the various factors which might cause growth,
there is no consensus. The following sections review (1) factors which
may influence future growth, (2) growth projections prepared by various
agencies and (3) the "best guess" projection recommended for environ-
mental assessment.
Influences on Future Growth
Some of the forces encouraging growth in the recent past will con-
tinue to operate in the future, and new forces may also materialize.
Tourism. Tourism in La Plata County is expected to continue to
expand in the future, although there are some doubts about the magnitude
of the expansion and the extent to which it will generate population
growth in Durango and the immediately surrounding area of La Plata
County. A major concern at present is the influence of the current
recession, but underlying that concern is a recognition of La Plata's
character as primarily an auto-oriented tourist area. With ever in-
creasing energy costs, areas like Durango may become relatively less
popular tourist destinations in the future. Not enough research on the
impact of high energy costs on travel patterns has been done to date to
allow any definitive statement on this point, but it does seem likely
that the rate of expansion of local tourism will stabilize or drop in
coming years, assuming that energy remains in short supply.
Another question is the degree to which tourism will generate
growth concentrated in the Durango area. The ski areas to the north,
Purgatory and Tamarron, are developing residential concentrations of
their own which may well result in less Durango-area growth. The
Purgatory ski area reportedly has approvals for about 1,080 dwelling
units, while Tamarron has approvals for about 100 units this year and
A-143
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will probably develop another 300 eventually along with convention and
golf facilities (Neal, pers. comm.). These units may well be primarily
used as second homes, but such a concentration may shift to the ski
areas residential development for employees and other support people and
related commercial development as well.
Energy resources development. Various studies have indicated the
presence of developable energy supplies in areas around Durango. One
study (Four Corners, 1978) maps areas of current and potential oil and
gas production, beds of known coal deposits of commercial value and
locations of geothermal resources. Much of the Southern Ute Reserva-
tion, which occupies an east-west strip in the southernmost part of La
Plata County, appears to have developable oil, gas and/or coal
resources, and several geothermal sites are located north of Durango.
The role of the proposed Animas-La Plata project in connection with
future energy resources development in the area has been much debated.
Current mining technology tends to be highly water-consumptive, and
shipping methods (such as pipelines transporting coal in slurry form)
can also use large quantities of water. It may be true that energy
resource exploitation in this area will not be possible without a major
water project such as Animas-La Plata, although facilitation of coal
extraction has not been the major argument in defense of the project.*
However, even if the Animas-La Plata project is implemented and
does assist in establishing energy resource activities in the La Plata
County, there is some question as to where the growth generated by those
activities would concentrate. The Animas-La Plata draft EIS indicates
that most growth relating to the construction of the water project would
* As stated in the draft EIS: "The long-term effect of project water
would be to fulfill a basic need in accommodating the future growth that
is expected to occur in the area irrespective of development of the
proposed project" (p. C-l).
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take place in la Plata County (90 percent; see p. C-l of EIS) . But the
Farmington area is within easy driving range and, as the major urban
concentration in the region, might be a stronger magnet for the 3,700-
person influx that has been suggested. Farmington had a 1976 population
estimated at 36,000 and it serves a much larger hinterland than does
Durango, providing a wider array of goods and services.
On the other hand, Farmington is held up as an example of the en-
vironmental problems growth can bring to rural parts of the mountain
states. Durango also offers a more physically attractive environment,
and housing costs are reported to be no lower in Farmington than in La
Plata County. There is evidence that some Farmington workers currently
commute to work from the Durango area (Durango Herald, May 27, 1980). So
if new employment is created in southern La Plata County - whether in
construction of the Animas-La Plata project or in subsequent energy
resources or agricultural development - it is difficult to say how
newcomers will judge the relative attractions of the two areas at that
time, and the ultimate effects can be expected to remain uncertain well
into the 1990's.
Agriculture. There are numerous soil types in southwestern Colo-
rado, of which generally the best for agricultural purposes is found on
the mesas, the result of wind deposits over millenia. At present, most
cultivation in the region is dryland (primarily dry beans and winter
wheat): the four major Irrigated crops in the region at present are
pasture, hay, small grains and corn silage. With the development of the
Animas-la Plata project, about 44,000 acres could be converted from dry-
land to irrigated agriculture, and increase of over twenty-two percent
in irrigated acreage. The 209 Water Quality Management Plan (the source
of the preceding description) emphasizes the importance of proper man-
agement to prevent excessive erosion and sedimentation where irrigation
systems are employed in rolling terrain.
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Of the five counties in State Planning Region 9, La Plata has the
highest proportion of irrigated agriculture, which is generally assoc-
iated with higher yields and higher agricultural income. In- the most
recent year for which data are available - 1974 - the county had about
57,000 acres of irrigated land out of a total of 291,000 acres in farms,
which is about twenty percent irrigated. That compares to a Region 9
total outside of La Plata County of seven percent irrigated.
There continues to be active agricultural production in the imme-
diate Durango area in the river bottoms, on the mesas and (grazing) in
the uplands. Although agricultural employment has been declining,
agricultural income has continued to rise during most of the last de-
cade, and this is consistent with national trends suggestive of ever-
increasing productivity of labor in American agriculture. The two
trends taken together result in increasing personal income per agri-
cultural worker: about twelve percent per year, for example, between
1970 and 1974 (Four Corners, 1978. based on data in Tables A-9 and
A-ll).
Most of the region's agricultural production is sold outside the
region. It seems likely that continued agricultural intensification,
which expansion of irrigated acreage would make possible, could have a
growth-inducing effect in such supportive industries as agricultural
services, retail and other services. However, as with tourism and
energy, the magnitude of the growth is uncertain, and the extent to
which newly irrigated lands would contribute to the economy of Durango
or of Farmington (or even some of the smaller communities) remains open
to question.
Factors discouraging growth. In addition to the high cost of
housing in the area which was discussed earlier, several other factors
may impede growth in La Plata County. Currently one of the most impor-
tant is the lack of major transportation links. The closest interstate
highway, 1-70, lies to the north at a distance of 169 miles. While good
quality highways do traverse the county, they are not limited access and
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movement can be interrupted regularly during the winter months. The
county has no rail freight service. Finally, because it does not lie on
a major transportation route connecting larger metropolitan areas,
transportation of goods in and out of Durango tends to be expensive,
contributing to high local costs of various goods and operating as a
disincentive for all but local-resource-based industries to locate in
the area.
A more long term consideration is the water supply. With the
development of the Dolores and the Animas-La Plata projects the five-
county region will have reached its maximum water development potential
(Four Corners, 1978). At that point, further development of urban,
industrial or extractive uses could be accomplished only be reductions
in agricultural water use through purchase of senior water rights.
Growth Projections
As the preceding description indicates, future growth in La Plata
County may arise from a variety of sources, but it is difficult to
forecast that growth accurately due to uncertainty as to the timing and
magnitude of external forces that will help shape the future of the
region - the supply of and the demand for energy resources being perhaps
the most important example.
Given this uncertainty, it is not surprising that various estimates
of the area's future population should diverge widely. Table 22 pres-
ents a series of such projections, which range from a year 2000 county
population of 28,000 to almost twice that level. Annual growth rates
associated with the projections range from 0.5 percent to 3.6 percent.
Among the projections given are two versions of "existing trends"
which are simple extrapolations of historical population statistics. If
only the decade of the 1970's is considered, then a growth rate of 3.4
percent describes recent trends; if one were to go back to 1950, a
growth rate of 1.9 percent applies. As a rule of thumb, economists
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TABLE 22
LA PLATA COUNTY POPULATION PROJECTIONS - YEAR 2000
Source
Resident Population
1980 2000
Year 2000 Estimate
Based on Projected
Growth Rate
Projected
Growth
Rate
Comments
OBERS, 1972 (U.S.
Water Resources
Council)
Existing Trends I
N.T.
N.T.
28,000
26,056
37,850
37,850
0.5%
1.9%
Annual growth date for Upper
San Juan Water Resources Sub-
area* is one-half percent over
1980-2000 period, which would
result in a year 2000 county
population of 28,000. Projec-
tions based on economic modeling.
Based on 1950-1978 county growth
rates
>
i
00
Animas-La Plata EIS
(U.S. Water and Power
Resources Service) 29,084
46,750
46,750
2.4%
Projections use 1970-76 statis-
tical data as the baseline in
applying the Bureau of Reclama-
tion Economic Assessment Model
State of Colorado,
Divn. of Planning 28,000
53,800
53,800
3.3%
Projections based on economic
modeling
Existing Trends II 26,056
50,850
50,850
3.4%
Based on 1970-1978 county growth
rate
208 Plan (Colorado
Dept. Local Affairs) N.T.
N.T.
54,650
3.6%
Annual growth rate for Bayfield,
Durango, Ignacio and Purgatory
analysis areas is 3.6 % over
1980-2000 period, which would
result in a year 2000 county
population of 54,650. Projec-
tions based on economic modeling
N.T . ¦ not tabulated.
-i/. r\T * _ -a ^
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preparing projections generally look back for as many years as they plan
to project forward. But that is only one of several considerations in
population forecasting. Another critical consideration is the extent to
which the past is judged to be similar to the likely future in terms of
the factors influencing population growth.
The difficulty in the case of Durango is that the similarity of the
recent past to the likely future is very hard to foretell. As a result,
while certain projections can be set aside as extremely unlikely, the
range of potentially realizable levels of growth is a fairly broad one,
with plausible annual growth rates probably lying in the 2.0 percent to
just over 3.0 percent range.
The very low OBERS rate can be set aside; the Bureau of Economic
Analysis (the Department of Commerce agency that prepares the OBERS
series) recognizes that the 1972 OBERS projections underestimated the
importance of factors encouraging growth in the Mountain, Pacific and
Southwest states. Another projection that be set aside (it is not
presented in the table) is that prepared by Henningson, Durham &
Richardson (HDR, 1977) for the Durango area (3.8 percent) because it was
based on an erroneous calculation of the annual growth rate over the 75-
year period from 1900 to 1975 of 3.5 percent; in fact, the annual rate
over that period was 1.77 percent (see the HDR report, p. IV-2).
Each of the other approaches can make certain claims to validity.
While an exhaustive review of the projection methodology in each case
might shed some light on forecasting problems, the fundamental diffi-
culty - and this is not uncommon - lies in determining what external
factors will influence local growth, and how much. Recognizing that
this is a question that, in fairly remote rural areas such as south-
western Colorado, is always going to defy the best attempts at accurate
response; it is suggested that a rate of 2.7 percent be accepted as a
"guesstimate;" this rate would result in a year 2000 population of
44,350 which lies midway between the lower and higher existing trends
projections and not far below the projection the Rireau of Reclamation
prepared for the Animas-La Plata project.
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This level seems plausible considering the presence of impediments
as well as stimli to growth, and it is more consistent with recent
experience than are the results of the two State economic models cited.
Accuracy of Projections
As noted in the preceding section, the projected growth rate for la
Plata is based in part on the assumption that the future will be similar
to the past in terms of the factors influencing population growth.
While this assumption does not necessarily require that the next twenty
years be a carbon copy of the past twenty to make the projection valid,
it does mean that significant changes in economic and demographic condi-
tions and trends as well as in technology could change the way people
live and, as a result, their likelihood of visiting or moving to La
Plata County.
Some of the national trends that have been observed and have
affected growth in the county during the past decade, for example, may
either accelerate or decline. The 1970's saw a marked increase in
personal real income (that is, incomes grew faster than inflation) and
consequently in people's tendencies to travel and to acquire second
homes. For the first time in U.S. history, rural (nonmetropolitan)
areas experienced greater population growth than metropolitan areas.
Longer life expectancies resulted in a larger population aged sixty-five
years or older, and the greater number of retired people moved to the
nation's sun belt.
The economic conditions of mid—1979 through mid-1980 call into
question the probability that these trends will be sustained. Rising
gasoline prices have inhibited the ability to travel; high inflation
rates have reduced real income growth; higher mortgage interest rates
have both slowed housing production and eroded many people's abilities
to purchase (and to sell) existing housing, which has in turn decreased
geographic mobility. These conditions may be a natural part of the
economic cycle or they may signal an end to or the beginning of a depar-
ture (of indeterminate length) from the cycle. Their influence on
county growth will become apparent only with time.
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Changes in local conditions, too, may affect the rate of growth in
La Plata County. For instance, construction of the Animas-La Plata
project would bring a temporary influx of population during the con-
struction period. It is not known whether these workers would attempt
to establish permanent residence in the area, nor is it known what the
long-term employment and population effects of the project - which
depend on the ultimate use of the water — would be.
Similarly, some recent growth has been attributable to the develop-
ment of ski areas in the northern part of the county. While development
of those areas is not yet complete and is expected to continue for
several years, it is not expected to continue to be a source of growth
through the end of the century. It is not known whether ski-related
development will be replaced with another type of activity that con-
tinues to generate growth in the county.
Finally, many county residents find jobs by opening small busi-
nesses. At some point, the local market will become saturated and this
source of economic development will not longer be available. The result-
ing lack of new jobs may have an inhibiting effect on population growth
not experienced in the past.
Location Of Growth Within La Plata County
The presence of 44,350 residents of La Plata County in the year
2000 would mean an increase of about 19,000 over the 25,231 residents
counted in the 1978 Dress Rehearsal Census. These new residents will
most likely choose where they live in the county based on a number of
factors, including where their jobs are (if they are employed when they
move to the area), where land is available, and the price of that land
relative to prices in other areas, the perceived advantages and dis-
advantages of various areas in terms of their own goals for living in
the county, and possibly some other factors.
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Land availability is a key influence in La Plata County. Much of
the land is owned or administered by public agencies including the U.S.
Forest Service, the Bureau of Land Management and the State of Colorado;
additional lands belong to the Southern Ute Indians. Approximately
forty percent of the county, or about 432,000 acres, is in private
ownership (Four Corners, 1978, p. II-8). This land is generally located
in an east-west band in the northern two-thirds of the southern half of
the county.
Some of the private land, while available for ownership, is unsuit-
ed to development because of physical constraints. For example, the
flood plain of the Animas River covers about one-third of the Animas
Valley north of Durango. Another problem is steep slopes, which may
have unstable soils or other geologic problems. A third problem is
water availability in some watersheds; groundwater tables are very low
in some places, making it difficult or expensive to drill successful
wells, and in other places there is not enough water to meet all the
demand for it. In the latter cases, senior (or preexisting) water
rights must be purchased by new development for that development to go
ahead.
The relative prices of land in various areas will also play a part
in determining where people live within the private ownership aras.
Table 23 summarizes land prices in the six 201/EIS study areas as one
May 1980. To some extent, price differences reflect the presence or
absence of other advantageous features; for example, Durango West, with
lots priced at $12,000, has paved streets with curbs and gutters, cen-
tral water and central sewage treatment.
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TABLE 23
COMPARATIVE SAMPLE LAND PRICES IN THE 201/EIS STUDY AREAS
Area
Price
Per Acre
Per Lot
Average
Lot/Parcel
Size
1. Hermosa
$12,000-14,000 0.5 to 6 acres
$8,000-10,000 0.5 acre
$ 8,000 23 acres
(1 parcel)
2. Junction Creek.
$2,000-2,500
0.5 to 2 acres
3, Lightner Creek
(too few sales to generalize)
Durango West
$12,000
0.4 acre
4. Grandview-Loma Linda $3,500
unknown
5. Florida Road
$5,000-6,000
$10,000
unknown
3 acres
6. West Animas
$6,000-7,000
unknown
a Close to Route 160 or other paved road,
b Very hilly terrain.
Source: Clayton Ebel, La Plata County Assessor, personal communication.
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The availability of land for private ownership establishes a geo-
graphic limit to the locations of future residential development, and
the relative prices for land begin to suggest the potential attractive-
ness and affordability of various areas within that geographic limit.
Other factors that provide indications of potential future growth pat-
terns are the past growth patterns, whether an area's current population
is full-time or seasonal, the nature of current development, the avail-
ability of water and other services, and local attitudes toward growth.
Another factor is the regulation of land used contained in the Land
and Resource Management Plan (LRMP) and the Comprehensive Plan for La
Plata County. The Comprehensive Plan is still in preparation, but
"desired growth plans" have already been adopted for two of the six
planning sectors in the county and a desired growth plan for a third
sector is currently being developed. These desired growth plans are
mandated for review every year; thus, while they do define the current
development guidelines, those guidelines cannot be regarded as unalter-
able. Further, land use planning is a controversial endeavor in La
Plata County and under attack from two directions this year: (1) the
LRMP, which sets forth policies and performance standards for develop-
ment, is the subject of a number of lawsuits and (2) two candidates for
County Commissioner have expressed anti-land-regulation commitments, and
if elected are considered likely to repeal all county land use regula-
tions. Therefore, while land use planning factors are described for
each area, they should be viewed in perspective. Factors influencing
growth in each of the 201/EIS Study Areas are discussed below.
Area 1: Hermosa
The Hermosa Study Area is located north of Durango along Highway
550. It is generaly bounded on the east by the Animas River, on the
north by Baker's Bridge, on the west by Hermosa Cliffs and on the south
by the leveling off of the valley that occurs just south of Trimble
Lane. Its focal point is Hermosa, a population center approximately
nine miles north of Durango.
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The Hermosa Study Area is divided into two subareas: Subarea la
encompasses the southern portion, extending about one-quarter mile north
of the Hermosa center. Subarea lb covers the remainder of the area,
extending north to Baker's Bridge. Subara la includes about 2,400
acres; Subarea lb includes about 1,800 acres.
Current Level of Development
The current population of the Hermosa area is about 1,700.* This
population is considered likely to be primarily full-time residents.**
Residential development in the Hermosa area includes approximately
665 living units. Of those units, about 255 are single-family resi-
dences, about 340 are mobile homes and about 70 are condominiums or
other multiple family structures (such as duplexes and four-plexes).
Subarea la contains about 465 of these units (149 single-family resi-
dences and 316 commercial mobile homes), for an average density of one
unit per five acres. Subarea lb contains the remaining 200 units, for
an average density of about one unit per nine acres.
Approximately 61 of the living units in the Hermosa area (all units
outside of mobile home parks) have been added since 1977, as shown in
Table 24. There are about 100 remaining parcels in the area ith no
structures on them, but this figure does not reveal how many of those
parcels are buildable, how many are owned by people already living in
the area or whether there are other constraints on their development.
(It is also not known how many could be subdivided and into how many
lots.)
*Based on dwelling unit count and population estimate in Hermosa Sanita-
tion District report (Allen, 1980). Household size derived from those
figures was also applied to approximately 200 living units in Area lb.
**Clayton Ebel, La Plata County Assessor, personal communication to
Gruen-Gruen + Associates, May 29, 1980.
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TABLE 24
RECENT RESIDENTIAL CONSTRUCTION IN HERMOSA STUDY AREA
Year
Single-family
Units
Mobile Homes
on Lots
Condo-
miniums
Total
1977
12
0
0
12
1978
31
0
0
31
1979
4
7
7b
18
1980a
0
0
0
0
Total
47
7
7
61
a January 1 through May 27, 1980.
b Included on one building permit.
Source: La Plata County Building Inspector's records.
Influences on Future Development
The future development of the Hermosa area will be affected by the
factors described below.
Physical constraints. Both the Animas River flood plain and the
steep slopes of Hermosa Cliffs limit the amount of developable land.
The flood plain covers about one-third of the valley, with its western
limit roughly halfway between the river and the highway (U.S. 550) north
of Hermosa center and virtually bordering the Denver & Rio Grande Rail-
road tracks in the vicinity of Trimble Lane. The cliffs pose a slope
and geologic hazard along the western boundary of Subarea lb.
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Land ownership. There are 386 parcels of land in the study area.
According to records in the La Plata County assessor's office, none of
them are owned by out-of-state-residents.
Land use planning. The recommended desired growth plan for Sector
3 of La Plata County, which includes the Hermosa area, shows an urban
core at Hermosa center, with residential development at densities rang-
ing from one living unit per acre to one unit per forty acres through
the remainder of the valley. Because the land use planning process and
the current land use regulations are under fire at this time, it is not
certain whether they will be operative in the future. Even if they are
set aside, however, the active opposition of Animas Valley and Hermosa
residents to increased density in the area may have some effect of
limiting the amount of future development.
Proposed major developments. There are currently several large
developments planned or approved for the Hermosa area, some of which
have already been started. At- full development, they would include
approximately 600 dwelling units, as shown in Table 25.
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TABLE 25
PROPOSED MAJOR DEVELOPMENTS; HERMOSA STUDY AREA
Name Number of Units
Blue Sky
James Ranch
Heraosa Townhouses
Total
a. About 50 units have been completed.
Source: Interviews with local sources.
Infrastructure. "Infrastructure" refers to the presence of water,
sewers and sewage treatment facilities, paved roads and other services
to property. Water in the Hermosa area is obtained from the Animas
Water Company or from on-site private wells, and is readily available.
There are no sewers; sewage is treated either in private septic tanks or
200
288'
110
598
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in private treatment plants, called "package plants" (for major subdivi-
sions and mobile home parks).* There is currently a ban on new permits
for package plants that would discharge to the Animas River, which would
restrict future development to that which could have septic tanks (that
is, development on lots of at least three acres.** A proposal to form a
Hermosa Sanitation District encompassing Subarea la, which would have
constructed and operated a local treatment plant in the vicinity of
Trimble Lane, was defeated in an election held June 10, 1980. Major
roads in the area - including the new and old highways, East Animas Road
and Trimble Lane - are paved, but many of the local streets are not.
Local attitudes. Area residents who attended the 201 study public
meeting expressed concern about and opposition to continued growth in
the Animas Valley. Some, however, said they thought it was inevitable
and pointed out that much growth had already occurred.
SuTnmary. Approved plans for major developments could allow the
population of the Hermosa study area to double. Local attitudes, recent
development and land prices all indicate that the area is an attractive
one, but major new developments may be inhibited by the restriction on
new discharge permits.
*San Juan Health Basin regulations prohibit septic tanks on lots smaller
than three acres which were platted after 1972 and on lots smaller than
one acre platted before 1972.
**Lloyd Hess, Region 9, Other sources have questioned the effectiveness
of this restriction.
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Area 2: Junction Creek
The Junction Creek study area covers approximately 2,400 acres
located north and slightly west of the City of Durango. Central fea-
tures of the study area are junction Creek Road and Chapman Lake.
Animas City Mountain rises on the east side of the area, and the San
Juan National Forest forms the northern boundary.
Current Level of Development
The current population of the Junction Creek study area is esti-
mated to be about 250 people, almost all of whom are full-time resi-
dents. According to the draft Facilities Plan, the area contains AO
single-family homes and 38 mobile homes, for a total of 78 living units.
Average density in the developed portions of the area is estimated to be
one living unit per 2.7 acres (Allen, 1980).
Building permits were issued for nine living units - all single-
family homes - between 1977 and May 1980. Three of the permits were
issued in 1978 and six were issued in 1979. There are an estimated 420
undeveloped parcels of land in the area.
Influences on Future Development
The level of future development in the Junction Creek study area
will be affected primarily by physical constraints, availability of
infrastructure and community attitudes toward growth.
Physical constraints. There are slope and hazard constraints on
the west and north edges of the study area and in the northwestern part
of the area. In the west and northwest, steep slopes occur west of
Junction Creek as the land rises sharply from elevations of about 6,700
feet to 7,500 feet and above. In the northeast, the northern slope of
Animas City Mountain descends abruptly toward the valley. Another
physical constraint is Chapman Lake, which fills with snowmelt early in
the year and dries out during the spring and summer.
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Land ownership. There are currently about 535 recorded parcels of
land in the Junction Creek study area. About 35 of these parcels are
owned by out-of-state residents. It is not known how many of these
parcels are undeveloped. To the extent that they are, their development
into full-time residences is likely not imminent, because they are
generally held for investment or for retirement use.
Land use planning. The Junction Creek study area is located in
planning Sector 1 of La Plata County. The desired growth plan for the
county, which has been adopted, allows residential development in the
valley portions of the area at maximum density of one unit per 10 acres.
Proposed major developments. Two major residential subdivisions
have been approved in the Juntion Creek area. The Jacob's Cliffs proj-
ect will contain about 180 lots at full development (only phase one,
with 34 lots, is currently platted) and the Durango Estates project will
contain about 400 lots (237 are currently platted). Both projects are a
number of years old and have seen little or no activity. One problem
for Durango Estates has been the lack of an access road, but that prob-
lem is reportedly being corrected at the present time (Yates, pers.
comm.). In addition to these two subdivisions, there is a smaller pro-
ject in the area: Sailing Hawks, with 16 recorded lots. These projects
are shown in Table 26. Falls Creek Ranch, a planned unit development
with 94 lots, lies outside the study area to the north and east.
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TABLE 26
MAJOR DEVELOPMENTS IN THE JUNCTION CREEK, STUDY AREA
Number of Units
Name
Currently Platted
Ultimate
Durango Estates
237
407
Jacob's Cliffs
34
180
Sailing Hawks
16
16
Total
287
503
Source: La Plata County Assessor and interviews with local sources
In addition to the projects that have already been approved,
several more are under discussion* The owners of Durango Estates are
beginning to discuss adding about 100 condominiums to the existing plan.
Other condominiums are under discussion in the vicinity of Chapman Lake.
In addition, between 200 and 300 acres of land have been offered for
sale by the Utah Electric Company, and this land oould be developed if
other conditions permit (Yates, pers. comm.).
Infrastructure. The Junction Creek area does have infrastructure
problems. Water availability is perhaps the most serious: lots platted
before 1972 have rights to household use (no exterior use, such as for
lawns, car washing or animals is permitted) and lots platted since 1972
must purchase senior rights.
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Wastewater treatment is provided by private septic tanks except at
the mobile home park, which has a package plant. Jacob's Cliffs has an
implied consent agreement to connect to the city's sewer line, but the
existing line cannot accommodate any flow beyond the amound added by
that project.
The only paved road in the area is Junction Creek Road, which is
also the only access road to the area. Turtle Creek Road, which pro-
vides access from Junction Creek Road to Falls Creek Ranch, is graded
but not paved.
Local attitudes. Based on the questions and comments raised at the
201 Study public meeting for Junction Creek, residents of that area are
generally opposed to growth and particularly to increased density there.
In general, speakers said that they had moved to Junction Creek to get
away from the city and did not want the city to follow them. An excep-
tion to this overall feeling was expressed by the owners of Sailing
Hawks subdivision.
Summary. The presence of large approved subdivisions creates
potential for significant additional residential development in the
Junction Creek area, but the historic lack of activity in those sub-
divisions, infrastructure problems and local attitudes suggest' that
ultimate development will fall short of the amount implied by the
approved plans.
Area 3: Lightner Creek and Durango West
Study Area 3 encompasses the two major existing areas of develop-
ment west of the city of Durango: Lightner Creek and Durango West. The
Lightner Creek subarea includes the land on both sides of U.S. Highway
160 west of Durango to the junction with County Road 207 and the land on
both sides of County Road 207 to the end of existing development. The
Durango West subarea includes the land on both sides of U.S. Highway 160
west of the junction to the western edge of the Durango West develop-
ment .
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Current Level of Development
The Lightner Creek-Durango West area has a current probable popula-
tion of about 960 people, most of whom are full-time residents. There
are an estimated 210 single-family homes and about 40 mobile homes in
the area (Allen, 1980), for a total of 250 living units. About 100 of
these units are located in Durango West. The density of development in
the Lightner Creek subarea is highly varied; in the developed portion of
the Durango West subarea, it averages about two living units per acre.
Building permits have been issued for 53 residential units in Area
3 since 1977, as shown in Table 27. There are approximately 135 platted
parcels in the area that currently have no structures on them.
Influences on Future Development
Future development in the Lightner Creek subarea will be limited by
the availability of undeveloped land and in both subareas by physical
constraints.
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TABLE 27
BUILDING PERMITS ISSUED IN LIGHTNER CREEK-
DURANGO WEST STUDY AREA, 1977-1980
Year

Number of Permits

Single-family
Residences
Mobile Homes
on Lots
Total
1977
0
0
0
1978
0
42
42
1979
11
0
11
1980a
_0
_0
_0_
Total
11
42
53
a January 1 through May 27, 1980.-
Source: La Plata County Building Department.
Physical constraints. Developable land in both portions of Study
Area 3 is limited by the steep slopes on both sides of U.S. Highway 160
and County Road 207 (except in the Durango West subdivision itself). A
further limitation in the Lightner Creek area is the flood plain of the
creek, even though this drainage was not included in the Flood Hazards
Report prepared by the u.S. Army Corps of Engineers (Allen, 1980).
Therefore, according to the draft Facilities Plan, the usable land in
each area is confined to "a very small strip up each valley that is out
of the active flood plain and below the surrounding cliffs"
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Land ownership. The Lightner Creek-Durango West study area con-
tains approximately 250 recorded parcels of land. Of those parcels, 47
are owned by ont-of-state residents. many of the out-of-state owner-
ships are of lots in the Durango West subdivisions. It is not known
what plans those owners may have for development.
Land use planning. The La Plata County desired growth plan for
Sector 1 designates residential development in the Lightner Creek area
at densities of one living unit per three acres along Highway 160
(between Durango and the Wildcat Canyon cutoff), one living unit per six
acres further west along Highway 160 (between the Wildcat Canyon and
Lightner Valley cutoffs) and one living unit per 10 acres further into
the valley along County Road 207.
The sector plan shows part of Durango West as a growth center,
defined as "an established center that contains urban densities and
uses." The area around the growth centr is planned for densities cate-
gorized as growth ring (future development area for urban densities and
uses), growth fan (one living unit per three acres) and highway rural
(one living unit per six acres). The latter category includes only a
small amount of land within the study area, south of the major areas
designated for denser development on the south side of U.S. Highway 160
Proposed major developments. The major new development in Study
Area 3 will be located in the Durango West subarea. Current approved
plans call for a total of 800 to 900 living units north of U.S. Highway
160 and an additional 400 units south of the highway. (These 400 units
include the 100 units already present.) There would also be a commer-
cial center south of the highway. The Lightner Creek subarea is con-
sidered to be fairly well developed, and no plans for major new projects
there are under discussion.
Infrastructure. The presence and condition of infrastructure is of
concern primarily in the Durango West subarea, because it is considered
the only potential new development location in Study Area 3. Durango
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West has central sewer and water systems as well as paved roads with
curbs. These features make it perhaps the best-equipped subdivision in
the Durango area, and help to explain why the selling prices of lots
there are so high ($14,000 for an 18,000 square foot lot; see Table 20
for comparative land prices.)
Local attitudes. People who attended the public meeting for the
201 wastewater facilities planning study area from Area 3 all resided in
the Lightner Creek subarea. These residents generally expressed the
opinion that growth in the Durango area is inevitable, and might as well
be accommodated in the most optimum manner.
Summary. The Durango West area is considered by a number of local
sources to be a prime growth area, because there are or will be many
lots available, it has good infrastructure and it is relatively close to
the city of Durango. Growth in Lightner Creek is likely to occur on a
smaller, piece—meal basis if at all because much of the buildable land
there is already occupied by some type of development.
Area 4: Grandview-Loma Linda
The Grandview-Loma Linda study area encompasses the major areas of
existing development south of Durango, generally along U.S. Highway 160
from around its junction with U.S. Highway 550 to about a mile east of
Elmore's Store and the cutoff to the La Plata County Airport (Colorado
Route 172). Along Highway 160, it includes the areas of Wilson's Gulch,
Grandview, Pinon Acres and Loma Linda. It extends south along Colorado
Route 172 to the Falfa area.
Current Level of Development
The current population of the Grandview-Loma Linda area is esti-
mated to be about 1,200 residents (Allen, 1980). These residents live
in 272 dwelling units, including 226 single-family homes and 46 mobile
homes in commercial parks. The average density of dwelling units varies
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from one per 1.5 acres west of Elmore's Store to one per 2.2 acres east
and south of Elmore's Store. There are also a number of motel units and
camper spaces in the area.
Development since 1977, as indicated by building permit activity,
has included 22 single-family homes and nine mobile homes on lots. This
activity is summarized in Table 28 . There are about 170 vacant parcels
of land in Area 4.
TABLE 28
RECENT RESIDENTIAL CONSTRUCTION IN
GRANDVIEW-LOMA LINDA STUDY AREA
Year
Single Family
Units
Mobile Homes
on Lots
Total
1977
3
0
3
1978
17
0
17
1979
2
9
11
1980a
0
0
0
Total
22
9
31
a. January 1 through May 27, 1980.
Source: La Plata County Building Inspector's records.
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Influences on Future Development
The availability of wastewater treatment facilities in Area 4 could
be an important influence on future development there, as indicated
below.
Physical constraints. The Grandview-Loma Linda study area has the
greatest amount of level land of any of the 201/EIS study areas. Slope
and hazard development constraints exist only in the western part, (1)
on both sides of U.S. Highway 160 in Subarea 4a from the western bound-
ary to the Grandview area and (2) along the west side of County Road 213
throughout Subarea 4b.
There is also a small portion of this area where flood hazards form
a physical constraint. It is also located in the western part of the
study area, around where U.S. Highway 160 turns eastward from the Animas
River. Overall, however, the physical constraint areas cover a small
proportion of the Area 4.
Land ownership. Of the 440 parcels of land in the Grandview-Loma
Linda area, about 15 are owned by out-of-state residents. As in the
other areas, it is not known whether these parcels are already
developed.
Land use planning. The adopted desired growth plan for La Plata
County Sector 6 shows two types of residential densities in the
Grandview-Loma Linda area: "highway rural," with a density of one living
unit per six acres, along Highway 160 (Subarea 4a) and "rural residen-
tial," with one unit per 10 acres, along County Road 213 (Subarea 4b).
Portions of the area not included in either of these two categories are
classified as "irrigated," a designation which presumes agricultural use
and makes development more difficult.
Proposed major developments. Animas Airpark is the only proposed
major new development in the Grandview-Loma Linda study area, with 39
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recorded lots. The consensus among local sources is that actual devel-
opment at the Airpark is still considerably in the future, potentially
following construction of a proposed shopping center south of Durango
and additional filling in of the industrial park.
Infrastructure. Water is generally available in the Grandview-Loma
Linda area, and is provided by private wells. Wastewater treatment is
accomplished by private septic tanks or evaporation ponds. There has
been some experience with failing septic system leachfields in the area
resulting from unfavorable soil conditions. Failed septic systems must
be replaced with alternative systems, which can cost about $5,000 and
are not guaranteed to work. This problem is perceived to be one reason
why the Grandview-Loma Linda area has not grown more rapidly and why
land prices there are comparatively low (see Table 23).
Another possible reason for .slow growth and low land prices is the
lack of paved roads in the area. Only the major thoroughfares - U.S.
160, Colorado 172 and County Road 213 - and a few other streets are
paved. Roads in the older subdivisions are generally simply bladed;
others are graveled.
Local attitudes. Residents of the Grandview-Loma Linda area who
attended the 201 Study public meeting for that area expressed mixed
opinions about the future of their area: some thought that growth would
be inevitable in the Durango area and that their neighborhood would be
the most logical next place for development, while others wanted to
avoid growth in the area. Other local sources also expressed mixed
views. Some believe it to be a natural growth area, particularly for
Animas-La Plata project construction workers if that project goes ahead;
others think that the poor soil conditions (for septic systems) and the
distance from the city of Durango make the area a less desirable
location than Durango West and Florida Road.
Summary. While the Grandview-Loma Linda area has the greatest
amount of land suitable for development in terms of topography, absence
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of steep slopes and flood hazards, it has some disadvantages for devel-
opment in its soil conditions, lack, of paved roads and distance from
Durango. Community attitudes toward growth are mixed.
Area 5: Florida Road
The Florida Road study area extends along Florida Road from the
Timberline View Estates entrance road a distance of about A.5 miles,
climbing 1,000 feet up the Spring Creek drainage to a natural low saddle
and then falling into the Florida River drainage. The study area is
divided into two subareas: 5a, which lies to the west of the saddle, and
5b, which lies to the east. Each subarea incompasses roughly half of
the 2,500-acre study area.
Current Level of Development
The current population of the Florida Road study area is estimated
at 283 people, living in 127 dwelling units. About fifty-six of the
dwelling units are located in Subarea 5a and about seventy-one are
located in Subarea 5b. Average density throughout the area is estimated
at one living unit per twelve acres. Twenty-two of the units in the
area have been added since 1977, as indicated in Table 29 . There about
ninety vacant recorded parcels of land in the study area.
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TABLE 29
RECENT RESIDENTIAL CONSTRUCTION IN FLORIDA AREA
Year
Single Family
Units
Mobile Homes
on Lots
Total
1977
2
0
2
1978
13
0
13
1979
5
2
7
1980a
0
0
0
Total
20
2
22
a. January 1 through May 27, 1980.
Source: La Plata County Building Inspector's records.
Influences on Future Development
The Florida area is considered locally to be a prime location for
future development because of its proximity to the city of Durango.
That development will be influenced by the following factors.
Physical constraints. Slope and hazard constraints cover much of
Subarea 5a, where the land rises steeply on the north side and very
steeply on the south side of Florida Road. There are similar conditions
on both sides of the road at the eastern edge of Subarea 5b. These
constraints leave most of the latter area and less than one quarter of
the former suitable for development.
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Land ownership. There are approximately 220 recorded parcels of
land in the Florida study area. Of those, twenty-eight are owned by
out-of-state residents. As in the other areas, it is not known how many
of the parcels owned by nonresidents are already developed.
Land use planning. The adopted desired growth plan for Sector 5
indicates decreasingly dense development along Florida Road as it moves
east. A small portion of Subarea 5a, at the western boundary, is in-
cluded in the growth ring that surrounds the city of Durango. While no
specific densities are defined in that area, it is characterized as a
"future development area for urban uses and densities." The center
portion of Subarea 5a is designated on the sector plan as a growth fan,
with a maximum density of one living unit per three acres. The eastern
part of Subarea 5a and all developable portions of Subarea 5b are
designated for highway rural densities of one living unit per six acres.
Proposed major developments. The only major development in the
Florida study area is Florida River Estates, a subdivision of 120 lots
which lies partly within the area. That subdivision, however, is esti-
mated to be 90 percent built as of early 1980 (Ebel, 1980, pers. comm.).
Several other current or proposed projects, located near the study area,
are described elsewhere.
Infrastructure. The physical infrastructure of the Florida area is
similar to most of the other study areas: the major thoroughfare
(Florida Road, in this case) is paved but local streets are generally
unpaved; water is provided by wells; wastewater treatment is accom-
plished by private septic systems. There are a few exceptions where
water is provided by central systems and wastewater treatment by package
plants.
The water supply in Subarea 5b (the Florida River drainage) is
legally constrained: developers must purchase senior water rights in
order to provide water to new subdivisions. This constraint is appar-
ently more legal than physical so far, as development in the area does
not seem to have been slowed by this requirement (Lyle, 1980, pers.
c oram .) .
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The water supply in Subarea 5a is not constrained but does have a
taste problem. This problem is considered by some sources to lessen the
area's attractiveness for development.
Local attitudes. Only one resident of the Florida study area
attended the 201 study public meeting for the area, which suggests that
there is not much local interest in a wastewater facilities project
there.
Summary. There are approximately ninety vacant parcels of land in
the Florida area, but these parcels are not concentrated in any parti-
cular location. Thus, any development that occurs will likely occur on
an individual basis. The major development that many people foresee in
this vicinity will probably be located outside the study area, either to
the west (near the Court Club) or to the east, particularly if Edgemont
Ranch is developed.
Area 6: West Animas
The West Animas study area is located between the City of Durango
and Hermosa west of U.S. Highway 550. Its southern boundary is north of
Animas City Mountain; its northern boundary is south of Trimble Lane.
The area covers about 170 acres.
Current Level of Development
The population of the West Animas study area is estimated to be 240
persons. There are 124 living units in the area, including seventy
single-family residences and 54 mobile homes in commercial parks. Of
the existing single family residences, eight have been added in the last
two years: four received building permits in 1978 and four more received
permits in 1979. There are only seven unbuilt parcels of land in the
area.
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Influences on Future Development
The West Animas study area is expected to account for relatively
little of the growth in the Durango area in the future, for the reasons
described below.
Physical constraints. The majority of the West Animas area is
subject to constraints on suitability for development. Virtually the
entire portion of the study area west of the old highway (U.S. 550) is
characterized by steep slopes. The new U.S. Highway 550 alignment
serves to some extent as a flood protection dike, but the 100-year
flood plain of the Animas River mapped by the U.S. Army Corps of Engi-
neers still covers both the southern and northern portions of the study
area that lie east of the old alignment. These conditions leave only
the central area between the two roads - the Falls Creek alluvial fan -
available for more intensive future development.
Land ownership. There are 114 recorded parcels of land in the West
Animas study area. All of them are owned by Colorado residents.
Land use planning. The proposed desired growth plan for the Animas
Valley (primarily in planning Sector 3) allows residential development
in this area at a density of one living unit per acre. This plan has
not yet been adopted, and its timetable for adoption is not known.
Proposed major developments. There is one pending major develop-
ment in the West Animas study area: Waterfall Village, which is a
ninety-unit condominium project. It has been approved by the La Plata
County Commissioners, but has been delayed as a result of the ban on new
effluent discharge systems ("package plants"). Its ultimate development
will depend at least in part on the resolution of water quality problems
in the Animas River above the city of Durango's raw water intake point.
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Infrastructure. The West Animas study area is supplied with water
by the Animas Water Company and, along with the Hermosa area (which is?r
supplied by the same company), is considered to have the best current
water availability of the study areas. Wastewater treatment is handled
primarily by private septic systems, with one package plant at the
mobile home park. Additional package plants are currently banned by the
San Juan Basin Health Unit because of water quality problems in the
Animas River (Hess, pers. comm., 1980). Both major roads in the area -
the new and old alignments of U.S. Highway 550 - are paved.
Local attitudes. The residents of the West Animas study area who
attended the 201 study public meeting generally expressed opposition to
growth and felt that a wastewater facilities project in their area would
be premature.
Summary. The lack of suitable land available for development and
the opposition of area residents to further development appear to vali-
date the general perception that West Animas will not be a major growth
area.
Summary of Study Area Development and Development Conditions
The foregoing analysis of existing development and influences on
future development conditions is summarized in Table 30 . The table
indicates that the Lightner Creek-Durango West and Florida Study Areas
have experienced the greatest relative growth since 1976 and have the
greatest proportions of out-of-state land ownerships. Infrastructure
conditions and availability vary among the six areas; Lightner Creek is
the only area considered to have average conditions in all three infra-
structure categories (roads, water and wastewater) while Durango West is
the only area considered to have better-than-average conditions for all
three.
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TA.BLE 30
SUMMARY OF EXISTING DEVELOPMENT AND DEVELOPMENT CONDITIONS, DURANGO 201 STUDY AREAS
Area
Existing
Population
Housing
Units
% of Housing
Unit6 Built
1977-19803
Number
of Vacant
Recorded
Parcels
% of
Out-of-
.State
Owners
Infrastructure
Roads Water
¦ b
Conditions
Waste-
water
1. Hermoaa
1,700
665
9
100
0
0
+
0
2. Junction Creek
250
78
12
420
7
-
-
0
3. Lightner Creek/
575
150

0
0
0

21
135
19

Durango West
385
100

+
+
+
4. Grandview-Lorna Linda
1,200
272
11
170
3
0
0
0
5. Florida
283
127
17
90
13
0
-
0
6. West Animas
240
124
6
7
0
0
+
-
a January 1, 1977 through May 27, 1980.
b indicates better-than-average conditions or availability;
"0" indicates average conditions or availability;
indicates below average conditions or availability.
Source: Cap Allen, Draft Wastewater Facilities Plan; La Plata County Building Inspector's records;
La Plata County Assessor's records; Gruen Gruen + Associates
-------
Other Potential Sites for Development
Future population growth and land development in La Plata County
will not be limited to the six study areas defined in the 201 wastewater
facilities planning process. Other areas in the Durango vicinity that
can expect significant growth are (1) the unincorporated private lands
in the county near the city of Durango and (2) the U.S. Highway 550
corridor north of Hermosa to the county line, which includes Purgatory
ski resort and several second home developments. The city of Durango
itself, as defined by its current corporate boundaries, has few develop-
ment sites. The towns of Bayfield and Ignacio will also experience some
growth, but it is likely to be minor compared to that in the locations
around and to the north of Durango, which are discussed in turn below.
Unincorporated Private Lands Near the City of Durango
There are a number of development projects proposed or approved for
the unincorporated area around the city of Durango. In large part, it
is these lands that are included in the Comprehensive Plan's estimate
that 2,800 additional dwelling units will be located in the city by the
year 2000.
Perhaps the largest of these projects is the Riverside planned unit
development, located immediately northeast of the city of Durango, which
has been approved by the La Plata County Commissioners. Development
there is scheduled to take place over nine years, and will ultimately
include 1,038 living units (227 single-family residences, 360 cluster
single-family homes, 136 townhouses and 315 apartments) plus commercial
space, open space and a recreation club. The project will have central
water and wastewater treatment facilities (eventually expected to be
connected to the City of Durango system).
Another major close-in development project is Hillcrest Mesa,
located on the mesa east of Durango near the golf course and Fort Lewis
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College. Preliminary plans for about 200 living units in this area have
been approved; it is not known when plans will be submitted for final
approval.
A third development location close to the city is the area along
Florida Road west of the 201 study area, in the vicinity of the Court
Club. Reports that K-Mart was planning to build a shopping center in
that area had a positive effect on land values there, which in turn made
feasible the redevelopment of some run-down existing structures. Cur-
rent development activity in that vicinity includes five condominium/
townshouse projects, with an estimated total of 95 living units, in
various stages of approval or construction.
Further away from the city, but still relatively close, are several
more potential development areas. To the southeast, past the Grandview-
Lotna Linda study area (about midway between Durango and Bayfield), is an
existing subdivision called El Rancho Florida. This subdivision has 13A
recorded lots in two subdivisions, but little or no existing construc-
tion. A third subdivision in the same project would be located to the
east of the existing project and would reportedly contain 250 lots
(Yates, 1980, pers. comm.). Other "further away" sites have potential
for longer-range development, as they have not yet entered the formal
development process and are discussed in the possibility or "the owner
wants..." mode. Among these sites are the Edgemont Ranch out Florida
Road to the east and approximately 2,000 acres in several ownerships out
wildcat Canyon Road to the west, in the same general area as the Rafter
J subdivision. The latter sites may have to' solve water availability
problems before development is feasible.
Areas North of Hermosa
The portions of La Plata County in private ownership that lie north
of the Hermosa study area along U.S. Highway 550 have recently experi-
enced rapid development as both recreational and residential areas. The
two types of activities are tied in with each other, and many of the
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residential units are condominiums owned by out-of-state residents for
second home use, either in conventional ownerships or in timesharing
arrangements.
Several of the existing developments have approved plans for ex-
pansion. The two major ones are Purgatory and Taraarron. The Purgatory
ski area, twenty six miles north of Durango, reportedly has approvals
for 1,080 additional living units. Tamarron, just south of Purgatory,
has approval for about 100 units this year (1980) and plans to build up
to 300 additional units by 1990 (Neal, pers. comm.).
There also appear to be a number of additional development possi-
bilities along the U.S. 550 corridor. Upwards of 250 acres of land
there are either owned by developers or on the market, and could hold up
to 200 high density (condominium or cluster) dwelling units (Yates,
person, comm.).
It should be remembered that residential development in this area
is primarily second home or retirement development. Approximately 530
properties, including roughly 475 condominiums, are owned by out-of-
state residents. (These figures do not include residents of other areas
of Colorado.) Therefore, while there will be substantial development in
this part of the county, only a small portion of it is likely to provide
homes for full-time residents.
HETEROLOGY AND AIR QUALITY
Heterology
A weather reporting station has been maintained at Durango since
1931 and is the source of information for the meterological characteri-
stics of the area.
The "Durango area has a relatively cool climate due to its elevation
and its topographic orientation. The annual average daily maximum
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temperature is 63.3°F and the annual average daily minimum temperature
is 29.1°F. Highest average monthly temperatures occur during July and
August (average monthly mean about 66°F) and the lowest average monthly
temperatures occur in December and January (average monthly mean about
27°F). On an annual average basis, approximately 209 days have minimum
temperatures of 32°F or less; only 12 days experience maximum tempera-
tures of 90°F and above. Between 1931 and 1973, temperature extremes
ranged from a low of -30°F recorded on January 13, 1963 to a high of
101°F recorded on July 5, 1973.
Snow occurs during every month except for June, July and August.
Typically the Durango area receives approximately sixty-three inches per
year with the greatest amounts occurring during December, January and
February. The average annual precipitation is 18.7 inches which is
typical of semi-arid environments. The driest months are June and
November and the wettest is August. Afternoon thundershowers during the
summer are characteristic of the area. The local topography causes
large variations in weather within short distances and occasionally
heavy thunderstorms cause damaging localized floods in small watersheds.
Precipitation generally increases and temperature decreases within
increasing altitude, but these variations are modified by the orienta-
tion of mountain slopes to the prevailing air currents and the effect of
the topographical features in creating local air movements.
Prevailing winds which are predominately from the west provide cool
temperatures during the summer and abundant moisture supplies for snow
during the winter. Cold artic air masses flow down from the north
beginning in the late fall and continue into the spring.
Air Quality
Only limited quantitative information is available for air quality
in the Durango Valley. The only air sampling instrument presently
operated in the area is a high volume sampler in downtown Durango.
Routine measurements are taken for total suspended solids (TSP), sul-
A-181
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fates, and nitrates. These data are summarized in Table 31. Sulfate
and nitrate concentrations are below the State mean. However, TSP
concentrations are typically near the established standard of 75 micro
3
g/m (annual average). In 1979 annual geometric mean TSP concentrations
exceeded the standard, while in the three previous years they were 70,
3
70 and 71 micro g/m respectively (Haig 1980 pers. comm.). The Colorado
Air Pollution Division anticipates continued monitoring of TSP concen-
trations but not of sulfates and nitrates.
Air quality is generally considered good and there are no current
air quality problems except for TSP concentrations. The source(s) of
this material is unknown. Smoke from fireplaces and stoves is a possi-
ble source of suspended solids. Particulates also may come from mud
carried to paved roads in the city during the winter and spring from
unpaved county roads and driveways. After drying on the pavement,
strong winds suspend the fine particles. Residential wood burning
stoves and fireplaces may also contribute to TSP concentrations during
the winter months.
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TABLE 31"
AIR QUALITY DATA FOR DURANGO (micro. g/m3)
Total Suspended Particulates
Primary Secondary Durango
Federal Standard Federal Standard 1977 1978 1979
Annual Geometric
Mean
75
60
69.68 70.96 81.44
Annual Arithmetic
Mean
-
-
76.00 79.48 86.59
Maximum 24-hour
Concentration
260
150
218 340 606

Nitrate
1978
Concentrations
1979
Sulfate Concentrations
1978 1979
Mean
1.27
1.08
2.64 2.40
24-hour Maximum
Concentration
9.3
4.5
00
•
00
CM
•
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REFERENCES
1. Stevens, T.A., P.W. Liptnan, W.J. Hail, Fred Barker, and R.G. Luedke,
Geologic Map of the Durango Quadrangle, Southwestern Colorado.
Department of the Interior, United States Geological Survey.
Miscellaneous Investigations Series. Map 1-764. Washington, D.C.
1974
2. U.S. Geological Quadrangle Haps with Modifications by Colorado State
Geological Survey. Geologic Hazards, Surficial Deposits, and
Mineral Resources in La Plata County
3. Soil Conservation Service. Soil Survey of La Plata County. Unpublished.
4. U.S. Army, Corps of Engineers. Flood Plain Information, Animas
River and Tributaries, Durango, Colorado. Sacramento, California,
June 1974
5. U.S. Army, Corps of Engineers. Flood Hazard Information Animas
River and Junction and Dry Gulch Creeks. Sacramento, California,
May, 1977
6. U.S. Army, Corps of Engineers. Flood Hazard Information. Animas
River and Hermosa Creek, Hermosa, Colorado. Sacramento, California.
October 1977
7. Owen, H.E. The Animas - La Plata Vegetative Project. 1975
8. Burdick, Hal. Final Report. Wildlife Inventory. Animas - La Plata
Project. Colorado Division of Wildlife. Montrose, Colorado.
August 1976
9. Somers, Preston. Final Report Fauna Inventory of the Animas - La
Plata Project Area. Fort Lewis College. Durango, Colorado.
September 1976
10. Smith, Norwin F. Aquatic Inventory Animas - La Plata project.
Final Report. Colorado Division of Wildlife. December 1976
11. State of Colorado. Colorado Water Quality Standards. Environmental
Reporter, 726:1001, July 20, 1978
12. Colorado Department of Health. Water Quality Control Division.
Water Quality Management Plan for the San Juan River Basin Colorado
Segment. Prepared by R. Keith Hook and Associates, Inc. Denver,
Colorado, October 1975
13. Colorado Department of Health. Water Quality Control Division.
Water Quality Survey of the San Juan Basin. By Mark Wuerthele.
Denver, Colorado June 1975
A-184
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14. American Public Health Association, American Water Work Association,
and Water Pollution Control Federation. Standard Methods for the
Examination of Water and Wastewater, Fourteenth Edition.
Washington, D.C. 1976
15. U.S. Environmental Protection Agency. Environmental Protection
Agency National Interim Primary Drinking Water Regulations.
Environmental Reporter, 132:0101, December 24, 1975. 41 Federal
Register 28402, July 9, 1976
16. Texas Water Development Board. The Texas Water Plan. Austin-,
Texas, November 1968
17. U.S. Environmental Protection Agency. Quality Criteria for Water.
Washington, D.C., July 1976
18. State of Colorado. Colorado Water Quality Standards. Environmental
Reporter, 726:1001, July 20, 1978
19. U.S. Environmental Protection Agency. Quality Criterial for Water.
Washington, D.C., July 1976
20. U.S. Environmental Protection Agency. Water Quality Criteria, 1972.
Washington, D.C., March 1972
21. U.S. Environmental Protection Agency. Environmental Protection
Agency National Interim Primary Drinking Water Regulations.
Environmental Reporter, 132:0101, December 24, 1975. 41 Federal
Register 28402, July 9, 1976
22. United States Geological Survey. Department of the Interior.
Availabilities and Chemical Characteristics of Groundwater in
Central La Plata County, Colorado. By Robert E. Brogden and T. F.
Giles, 1976
23. Colorado Department of Water Resources. Master List of Wells by
Location. Denver, Colorado, December 1978
24. U.S. Environmental Protection Agency. STORET data.
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APPENDIX B
ENVIRONMENTAL IMPACTS
-------
ENVIRONMENTAL IMPACTS
Environmental impacts associated with implementation of the pro-
posed alternatives to provide wastewater management to the Study Area
are presented in this appendix. Impact discussions are organized
according to technical discipline in order to facilitate review and
comment by regulatory agencies. The arrangement of technical discipline
discussions follows that of Chapter 4 Affected Environment of the
Environmental Impact Statement.
B-l
-------
TOPOGRAPHY
Project Impacts
The proposed alternatives will have little affect on the topography
of the area. However, this feature of the existing environment does
influence the suitability of various wastewater alternatives in the Study
Areas. Slopes too steep for excavation equipment effectively limit the
construction of leach fields for on-site disposal systems. Excessive
slope also limits the effectiveness of on-site leach field systems,
because adequate percolation from the leach field may not occur. In
alternatives recommending sewering, topography becomes a significant
factor when collection systems are extended into areas where slope does
not permit gravity flow in the sewers. Such areas will require an initial
outlay of money and resources for the construction of pump stations, plus
a permanent electrical energy demand to move the sewage.
Mitigation Measures
State regulations governing individual sewage disposal systems
require a registered sanitarian or a registered professional engineer to
determine ground slope suitability during the Health Department's review
of the permit application.
To avoid permanent electrical energy requirements to pump sewage uphill,
local treatment can be provided in areas to be sewered. The preferred
alternatives for both the Hermosa and Loma Linda areas include providing
local central treatment rather than pumping sewage uphill to the Durango
wastewater treatment facility.
GEOLOGY
Project Impacts
The proposed projects will have few if any identifiable impacts
on geology. However, geologic features affect the selection and siting
of wastewater treatment alternatives. Shallow bedrock limits the effect-
iveness of on-site leach field disposal systems due to the difficulty of
obtaining adequate percolation from the leach field. Pipeline construction
is both more difficult and more expensive in areas of shallow bedrock.
Facilities built in the area of geologic hazards or potential geologic
B-2
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hazards may be damaged or destroyed if movement occurs within the area.
Mitigation Measures
Inadequate treatment by leach field systems due to shallow bedrock
can be avoided by adequate pre-construction testing to acertain that soils
are deep enough to provide suitable treatment. Facilities should not be
built in areas determined by the Colorado Geological Survey to have
unstable slopes or other geologic hazards.
SOILS
Project Impacts
There are several impacts on soil resources associated with the
wastewater treatment alternatives proposed for the Study Area. All alter-
natives that include construction of new facilities or pipeline install-
ations will result in a temporary displacement of soil until backfilling
is complete. Disturbed soil is a visual scar and is susceptible to
erosion. All alternatives that include subterranean release of effluents,
such as the No Action and Formation of Maintenance District alternatives,
will continue to affect the assimilative capacity of the soil mantle.
Construction of new wastewater treatment facilities, such as the proposed
lagoon systems for the Hermosa, Grandview, and Loma Linda areas, will
result in the permanent removal of that soil for other uses.
The most important impacts to soils in the Study Area, however, are the
indirect impacts associated with increased growth. Development in some
areas, and especially in the Grandview/Loma Linda area, is constrained by
a lack of adequate sewage treatment and disposal. Providing sewers and
sewage treatment to these areas will remove that constraint and will
accommodate new growth. Such growth will require conversion of land to
urban uses, with consequent loss of soil resources. The significance
of the loss depends on the amount of growth that occurs, the amount of
soil involved, the soil's value as a productive resource, the erosion
potential of the soil, and other similar factors.
The existing soil conditions impose a number of constraints on the
alternatives under consideration. These constraints would not necessarily
prevent implementation of any of the alternatives, but they were factors
B-3
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considered in selecting the recommended plans. Recommended percolation
rates for absorption beds are five to 60 minutes per inch. Soils in
such areas as alluvial deposits have rates faster than that, while such
areas as Grandview/Loma Linda generally have much slower rates. These
areas are constrained for successful operation of on-site land disposal
systems. In other areas, such as along U.S. Highway 160 from Wildcat
Canyon to the Lightner Creek Road turnoff, difficult terrain and shallow
rocky soils would complicate digging the trench for an interceptor line,
and would result in higher-than-normal maintenance costs for the line.
Mitigation Measures
Most of the direct impacts of any alternative can be mitigated by using
standard engineering practice to minimize disruption of soil and underlying
strata during construction, and by requiring restoration of disturbed
surfaces and revegetation where appropriate. Soil losses due to construc-
tion of new treatment facilities will be balanced by the reclamation of
land currently occupied by existing package plants.
Indirect growth-related impacts can be minimized by strict adherence
to the desired growth patterns designated in the La Plata County Compre-
hensive Plan. Adherence to the plan would channel growth into existing
urban areas or their peripheries, and would discourage development in
rural areas. New development would thus be directed into areas where
the soil resources are already substantially disturbed. Adherence to
land use plans and ordinances is a local matter, however, and EPA has
limited authority over decisions made at the discretion of local author-
ities.
WATER RESOURCES - SURFACE WATER HYDROLOGY
Project Impacts
The alternatives proposed for wastewater management would have several
affects on surface water hydrology in the Study Area. The various alter-
natives could potentially influence stream alignment and streambed com-
position, streamflow volumes, the floodplain, and even portions of the
watershed.
Anywhere a proposed pipeline crosses a stream channel, such as the
Lightner Creek crossing in the recommended Lightner Creek alternative,
B-4
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the flow characteristics of the waterway at that point will be altered.
In addition, materials placed in the channel for pipeline stabilization
and erosion protection will permanently alter the stfeam bed at the
crossing site.
Stream flow will be temporarily disrupted during construction activ-
ities. However, more permanent alterations in stream flow will result
from alternatives involving sewers and remote treatment. In the Hermosa
area, the recommended central treatment facility will discharge treated
effluent to the Animas River. Although part of this effluent will consist
of wastewater currently being discharged to the Animas River by existing
package plants which will be replaced, it will also include wastewater
that is currently treated by on-site leach field disposal. The Animas River
will have a net gain, albeit small, in total streamflow. Discharge from
the recommended Grandview lagoon system into Wilson Gulch and thence to
the Animas River will also contribute new flow to the river. Wastewater
in the Grandview area is currently disposed of primarily by evaporation.
A net increase of about 100,000 gallons per day in the Animas River can
be expected from this facility. The recommended alternative in the Junction
Creek Study Area will result in decreased flows in Junction Creek. The
wastewater currently discharged to Junction Creek by the Junction Creek
Mobile Home Park will instead be piped to the Durango wastewater treatment
facility for ultimate discharge into the Animas River. This option will
not result in a change in Animas River flow, however, because Junction Creek
is tributary to the Animas River.
Much of the development within the narrow Animas Valley has been on
the flood plain. Flood plain development has also occurred along Lightner
Creek, Junction Creek, Hermosa Creek, and Spring Creek. Sewers could
facilitate further development in these areas unless proper safeguards
are instituted. The recommended wastewater treatment facility for the
Hermosa area will be located within the 100-year flood boundary, and
proposed sewer alignments traverse portions of the 100-year flood plain.
Development in flood plains can potentially restrict flood flows, increase
water velocity, alter flood plain boundaries and contribute to property
losses. Flooding of treatment plants, interceptor sewers, collection lines,
B-5
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and on-site sewage disposal facilities can cause an interruption in treat-
ment of wastewater and create public health hazards. One positive impact
of providing sewers in the Hermosa area is the elimination of the Hermosa
Meadows package plant which, is located in the flood hazard area.
There will also be long-term, indirect effects on surface hydrology.
Many of the alternative plans involving sewering could accommodate or even
encourage growth in the Study Area. Additional land will be developed as
this growth occurs. This development could noticeably affect surface
hydrology if it results in substantial watershed modifications.
Surface water hydrology imposes constraints on the alternatives
considered for the Study Areas. For example, providing sewers in Lightner
Valley from U.S. Highway 160 to Safari Campground was rejected because
large portions of the alignment would be in the flood hazard area or 100-
year flood plain, and multiple pipeline crossings of Lightner Creek would
be required.
Mitigation Measures
In most cases, impacts of the recommended alternatives to stream
channels and stream flows will be insignificant due to the short lengths
of stream and minor volumes of water involved. These impacts are inherent
in the management strategies selected, and little can be done to mitigate
them.
To mitigate the possibility that selected alternatives providing sewers
will facilitate development in flood hazard and flood plain areas, the
EPA has stipulated the following grant conditions:
1. The grantee and local jurisdiction shall not accept a
sewerage connection to any interceptor funded by this grant,
from any residential, commercial or industrial structure receiv-
ing a local building permit after the date of this grant, if
the structure is located within a designated 100-year flood
plain. The grantee and local jurisdictions are permitted to
accept a sewerage connection from any residential, commercial
or industrial structure located within a designated 100-year
flood plain, if the structure is in existence or was issued a
local building permit prior to the date of award of this Step
2 grant.
B-6
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A variance to this condition will be considered by EPA
if the grantee submits site-specific documentation (including
detailed maps of specific plats recommended for variances)
that there is no practicable alternative to development within
the 100-year flood plain. A minimum requirement for a variance
to be granted is a demonstration that the proposed structure
will comply with the flood plain management standards of
the National Flood Insurance Program and that the proposed
flood plain development will not alter the 100-year flood
plain so as to increase the risk of flooding to upstream or
downstream property. Under no circumstances will a variance
be granted for development to be located in the floodway as
defined by the National Flood Insurance Program and identified
on HUD Flood Boundary Maps. The grantee should refer to Federal
Executive Order 11988 dated May 24, 1977, pertaining to "Flood-
plain Management" and EPA's "Statement of Procedure for Flood-
plain Management and Wetlands Protection", dated January 5,
1979 (44 CFR 1455).
2. Prior to receiving a Step 3 (construction) grant from
EPA for any portion of the approved facility plan, the grantee
shall, in cooperation with, other local officials'and flood
plain owners, formulate a plan and implementation schedule for
removing relocatable dwellings from the flood hazard area as
defined by the Federal Emergency Management Agency and for
providing flood proofing to improvements within that portion
of the 100-year flood plain that lies outside the flood hazard
area.
The first condition is self-explanatory. Adherence to the second condition
will include providing protection for the Hermosa wastewater treatment
facility against a 100-year flood, and installing pipelines in the flood
areas with sufficient depth and over—burden to protect against erosion
during possible flood conditions.
Indirect growth-related impacts can be minimized by strict adherence
to the desired growth patterns designated in the La Plata County Com-
prehensive Plan. Adherence to the plan would channel growth into existing
urban areas or their peripheries, and would discourage development in
areas where the watershed is relatively undisturbed. Adherence to land
use plans is a local matter, however, and EPA has limited authority over
decisions made at the discretion of local authorities.
B-7
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WATER RESOURCES - SURFACE WATER QUALITY
Project Impacts
Sewering alternatives that include replacement of inadequately operating
wastewater treatment facilities that discharge either directly or indirectly
to surface waterways will result in an improvement in surface water quality.
Formation of a Maintenance District would also result in improved water
quality through better operation and maintenance of existing equipment.
Sewer alternatives that include treating and discharging wastewater
that was not formerly discharged either directly or indirectly to surface
waterways will result in degradation of surface water quality. For example,
little wastewater generated in the Grandview area currently enters surface
waterways. The effluent from the recommended discharging lagoon will add
new amounts of heavy metals, residual chlorine, and nutrients such as
nitrogen and phosphorus to the Animas River. Such effluent components
could adversely affect aquatic resources by promoting algal blooms or by
causing toxic effects to biota.
Alternatives involving construction activities would result in a
temporary increase in siltation due to increased soil erosion.
Mitigation Measures
The most important measure to minimize detrimental effects of consti-
tuents of "new" wastewater on surface water quality is to make certain that
treatment plants are operating properly at all times. This includes having
facilities that are well designed, built, and maintained, and having
treatment plant operators who are well trained and highly motivated.
Providing better operation and maintenance of existing equipment
and/or replacing failing equipment are mitigation measures for the No
Action and Maintenance District alternatives which involve continued
reliance on existing wastewater treatment methods.
Using standard engineering practices which minimize disruption of
soil and expose it to increased erosion for only a short period of time
will minimize siltation of waterways.
WATER RESOURCES - GROUND WATER HYDROLOGY AND QUALITY
Alternatives that provide sewers to areas currently treating
B-8
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wastewater with, septic tank-leach, field systems or other land disposal
methods will tend to decrease ground water resources. Not only will
sewers reduce percolation of wastewater into the water table, but infil-
tration/inflow into the pipes may drain away existing ground water.
Ground water quality will improve or be protected from further degra-
dation by implementation of any alternative except the No Action alternative.
Maintenance District alternatives would provide improved maintenance and
operation of existing facilities and would also require the upgrading and/
or replacement of inadequate treatment systems. Sewering alternatives
would eliminate subsurface discharge of effluent. Although subsurface
disposal systems usually provide adequate treatment, the effluent will still
impact ground water quality because of the nature of that treatment. Most
of the treatment will occur in the soil material in and below the leach
field component, where organic matter and pathogenic organisms will be
physically strained and oxidized. Oxidation will result in organic
matter and other compounds such as ammonia being converted to more stable
forms that are usually ionic. Some of the ions will be absorbed to soil
particles or chemically precipitated as insoluble forms. However, the
ability of soil to accomplish this removal is limited and, at some point,
there will be a "breakthrough" and most of the ionic matter in the percolat-
ing wastewater from that time on will be conveyed into the water table.
The removal capacity of the soil would differ considerably among the
different ionic species that are present in wastewater. If the hydraulic
loading factor is too rapid, the ammonium ion (which is in chemical
equilibrium with unionized ammonia) may not be fully oxidized to the stable
nitrate ion. In this case, breakthrough can occur and result in ground
water contamination by ammonium. The above factors can result in a slow
increase in mineral and nutrient concentrations in the ground water, with
the rate of increase dictated by the loading component,the size and design of
the leach field,the amount of ground water available for dilution, and the
rate of movement of ground water through the Study Area. This discussion
also applies to land treatment/disposal options as well as to the contin-
ued use of individual on-site and multiple-customer disposal systems. Thus,
even through the current treatment and disposal methods appear to be
adequate in most systems, increases in ground water levels and/or in pop-
ulation density could render existing systems unsuitable.
B-9
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Mitigation Measures
The direct impacts to ground water hydrology associated with the various
alternatives are inherent in the management strategies, and little can be
done to alter these impacts. However, these impacts do not appear to be
significant due to the relatively small volumes of water involved.
Alternatives involving providing sewers are, in a sense, mitigating
measures for the existing ground water quality situation. The water
quality impacts of these alternatives are inherent in the management strat-
egies proposed and do not present much opportunity for additional mitigation.
For Maintenance District and No Action alternatives, vigilant maintenance of
existing facilities, both on-site disposal systems and package plants, to
ensure proper operation is the best protection against ground water quality
degradation. Ground water quality monitoring programs would provide a
check on the operation of subsurface discharging systems under No Action or
Maintenance District alternatives. The monitoring would provide a warning
if disposal systems were not functioning properly.
BIOLOGICAL RESOURCES - VEGETATION
Project Impacts
The direct effects of any of the alternatives on vegetation are
fairly small. Few if any effects would be caused by the No Action or
Maintenance District alternatives. Alternatives involving construction
would result in a complete loss of vegetation over pipeline alignments and
at the sites of new sewage treatment facilities.
Indirect effects to vegetation by alternatives that would accommodate or
encourage increased growth (sewering alternatives) could be substantial.
Such growth will require conversion of land to urban uses, with consequent
loss of vegetation resources. Loss of vegetation on building sites and
roadways would be complete; vegetation in adjacent areas would probably
be altered from climax native species or agricultural crops to lawns and
ornamental species. The significance of this loss depends on the amount
of growth that occurs in the Study Area, and the amount of growth that
occurs outside of designated high density urban areas. Increased human
activity associated with growth may also impact vegetation resources.
B-10
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Recreational activities such as cross-country motorcycling and four-wheeling
can damage or destroy vegetation, while firewood gathering removes both
vegetation and nutrients from a site. There is also the potential for
increased fire hazard due to increases in human activity.
Mitigation Measures
Vegetation losses along pipeline alignments can be mitigated by
disrupting as narrow an area as possible during construction, and by re-
vegetating the area when construction has been completed. Losses of vege-
tation under new sewage facilities can be mitigated by reclaiming and
revegetating land currently under package plants which will be replaced.
Indirect growth-related impacts can be minimized by strict adherence
to the desired growth patterns designated in the La Plata County Com-
prehensive Plan. Adherence to the plan would channel growth into the exist-
ing urban areas or their peripheries and would discourage development in
rural areas. New development would thus be directed into areas where the
vegetation is already substantially disturbed. Adherence to land use
plans and ordinances is a local matter, however, and EPA has limited
authority over decisions made at the discretion of local authorities.
BIOLOGICAL RESOURCES - WILDLIFE AND SPECIAL STATUS SPECIES
All Special Status species in the Study Area are animals. They include
the Federally endangered peregrine falcon, the Federally threatened bald
eagle, and possibly the State endangered lynx.
Pro.j ect Impact
The No Action and Maintenance District alternatives would have few if
any direct impacts on wildlife. Alternatives involving construction of new
facilities, however, could have potentially significant effects on wild-
life in the Study Area. Construction would result in a complete loss of
wildlife, primarily small mammals, birds, and herptiles, over pipeline
alignments and at the site of new sewage treatment facilities. More impor-
tant, construction activities through wildlife habitat during critical
breeding, calving, or wintering periods could cause severe population
declines. The Study Area has a large wintering population of bald eagles
that occurs primarily along the Animas River and it tributaries (Figure
4.17 in the EIS). Disturbances such as construction along these corridors
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could cause the eagles to leave the area. Large portions of the Study Area
are deer fawning/elk calving areas, as shown in Figures 4.13 and 4.14
of the EIS. Disturbances caused by construction and heavy machinery during
the calving/fawning periods could result in stress that might cause abortion
of fetuses or the abandonment of young animals by their mothers. Large
areas are also winter habitat, including critical wintering habitat for
elk and deer. Construction-associated stresses could weaken animals during
this particularly vulnerable period, and could also cause increased energy
expenditure as animals moved away from construction. Serious as they are,
however, such impacts would be only temporary, ending after construction was
completed and populations had rebuilt to former levels.
More permanent effects would result from indirect growth-related im-
pacts. Alternatives that would accommodate or encourage increased growth
(sewering alternatives) could have serious consequences to wildlife pop-
ulations. Such growth will require conversion of land to urban uses, with
consequent loss of wildlife habitat. Most detrimental would be the loss
of critical winter ranges which for deer and elk are shown in Figures 4.13
and 4.14 in the EIS. Loss of critical winter range to urban uses would prob-
ably cause a prompt, severe, and permanent decline in wildlife populations
in the area. Loss of habitat in other wintering areas, fawning and calving
areas and/or feeding areas would cause a more gradual but permanent decline
in wildlife populations. Intrusion into riparian corrdors by growth could
destroy critical roost trees for bald eagles or cause stress to the dis-
turbance-sensitive birds. Either factor would result in a decline of this
Federally threatened species in the area.
Increased disturbances to wildlife caused by increased human and pet
activity associated with growth are other serious indirect impacts that
could occur. This is a special concern where residential areas are ad-
jacent to relatively unaltered wildlife habitat, as in this Study Area.
Illegal shooting of wildlife, including raptors such as eagles, and poach-
ing are very difficult to control when residential and wildlife areas are in
close proximity. Domestic pets also impact wildlife populations. Dogs and
cats are predatory in nature and will hunt wildlife even when adequately
fed by their owners. Domestic pets can function as predators maintained
at artificially high levels and as such can cause drmatic declines in
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wildlife populations. Cats will hunt primarily small mammals and birds.
Dogs hunt these species as well as larger animals, and in packs can even
kill deer and elk. Wildlife populationsare most vulnerable to human and
pet disturbances during the winter and when the young are new and helpless.
Mitigation Measures
Direct wildlife losses due to pipeline and facilities construction
can be mitigated by restoring the habitat as quickly as possible. Construc-
tion—related disturbances can be effectively avoided by staging activities so
that construction does not occur in a critical habitat during a critical
time period.
The most effective way to minimize indirect growth-related impacts
on wildlife is by strict adherence to the desired growth patterns desig-
nated in the La Plata County Comprehensive Plan. Adherence to the plan
would channel growth into existing urban areas or their peripheries, and
would discourage development in rural areas. New development would thus
be directed into areas where wildlife is already substantially disturbed.
Adherence to land use plans and ordinances is a local matter, however, and
EPA has limited authority over decisions made at the discretion of local
authorities.
The indirect growth-related impacts of urban intrusion into critical
winter range can be partially mitigated by identifying the most important
habitat, placing it under public ownership to prevent development, and
applying wildlife management practices to increase its carrying capacity.
Intrusion into riparian corridors can be prevented by ordinances prohib-
iting development of flood plains, and by developing greenbelt parkways
in riparian areas. Particularly sensitive areas such as bald eagle roost
trees, peregrine falcon nesting or hacking sites, and critical wildlife
winter range should be closed to public access during critical periods.
Strict enforcement of leash laws would substantially reduce harassment
and predation of wildlife by pets.
BIOLOGICAL RESOURCES - AQUATIC LIFE
Project Impacts
Degraded water quality has an adverse impact on aquatic life. The
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resulta of water quality monitoring conducted in the Study Area are in-
conclusive and do not confirm degradation of water resources by existing
wastewater treatment systems. However, many of the package plants in
the Study Area have a history of operations problems, and some on-site
disposal systems have inadequate percolation rates or are located in areas
of high ground water. The No Action alternative would result in a
continuation of this situation.
Enactment of Formation of Maintenance District alternatives would
probably have a beneficial impact on aquatic life. By requiring replacement
of failing systems and providing better operation and maintenance of existing
systems these alternatives would either improve aquatic habitat or protect
it from further degradation.
Alternatives providing sewers would eliminate the possibility of
aquatic habitat degradation by inadequately treated wastewater. However,
by providing treatment and surface water disposal of sewage that is currently
disposed by evaporation or land-disposal systems, these alternatives will
introduce additional amounts of heavy metals and nutrients such as nitrogen
and phosphorus to the aquatic habitat. Heavy metals plus residual chlorine
released with the effluent could have toxic effects on the biota. Increased
nutrient loads could promote algal blooms with associated oxygen depletions
that can result in fish kills.
Indirect growth-related impacts could also be associated with providing
sewers and surface water discharge of effluent. Increased population would
produce increased amounts of nutrients and heavy metals, which would be re-
leased with increased amounts of treated effluent. In addition, increased
conversion of rural land to urban areas would result in increased runoff
as less water would be absorbed by the ground. The runoff would carry silt,
sediment, and heavy metals associated with urban areas, all of which would
degrade the aquatic habitat.
Mitigation Measures
The best way to mitigate aquatic habitat degradation is to insure
that all wastewater treatment facilities, from septic tanks to central
treatment plants, are operating properly at all times and are providing the
best sewage treatment possible. The addition of "new" wastewater to
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aquatic habitats by sewering alternatives is inherent in the management
strategy, and little can be done to alter this impact. In addition, little
can be done to mitigate increased wastewater volumes, and surface runoff
problems associated with increased growth.
METEROLOGY AND AIR QUALITY
Pro.j ect Impacts
Heterology is neither expected to have impacts on nor be impacted by
any of the proposed alternatives.
Indirect growth-related impacts to air quality in the Study Area are
expected if alternatives that remove constraints to development (sewering
alternatives) are enacted. Primary sources of air pollution in the area
are automobiles and home fireplaces. Increased numbers of both with pro-
portionate increases in air emissions are expected with increase in pop-
ulation in the area.
Mitigation Measures
No mitigation measures are proposed for air quality impacts.
ENERGY RESOURCES
Project Impacts
The No Action and Formation of Maintenance District alternatives
would result in no net change in energy consumption. While such systems
as on-site septic tank-leach field systems require no energy, other facil-
ities in the Study Area, including several of the package plant systems
which are overloaded, are quite energy intensive. Providing sewers under
the recommended plans for the Hermosa, Junction Creek, and Grandview/Loma
Linda areas would result in annual energy savings of 206,000 kwh, 26,000 kwh
and 28,000 kwh, respectively, due primarily to the replacement of inefficient
package plants.
Sewering alternatives that could accommodate or encourage increased
growth in the Study Area would have indirect impacts on energy consumption.
Increases in population in the Study Area could be expected to produce a
proportional increase in energy consumption.
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Mitigation Measures
Providing sewers to areas where energy intensive package plants
currently treat wastewater is in effect a mitigation for current high energy
consumption in sewage treatment. Indirect growth-related increases in
energy consumption could partially be mitigated if local governments would
amend building codes to require new construction to include adequate
insulation and other energy conserving devices.
TRANSPORTATION
Project Impacts
There will be direct impacts on the road system in the Study Area as
a result of any alternatives implemented. Under the No Action and Formation
of Maintenance District alternatives, on-site disposal units would have to
be pumped periodically and the septage hauled by truck to the Durango waste-
water treatment plant. Enactment of Maintenance District alternatives
would probably result in increased pumper truck traffic because of better
maintenance, including more frequent pumping, of existing facilities.
Direct impacts of alternatives involving construction of new facilities include
movement of construction equipment on area streets and possible road damage
done by heavy equipment. Construction of interceptors along highways could
disrupt traffic during the period of construction, while construction of
new pipelines across roadways would both disrupt traffic and destroy short
segments of the current roadbed.
Indirect effects are related to the additional vehicular traffic that
will result from growth accommodated by providing sewers in areas presently
constrained by inadequate wastewater treatment. It is not expected that
significant road capacity problems in the Study Area will occur as a result
of the growth associated with this project. However, any roadway problems
and adverse driving conditions that presently occur during the winter season
are likely to continue and get worse as more vehicles enter the area.
Mitigation Measures
Standard engineering practices and staging of construction to disrupt
traffic flow as little as possible should be used during construction activ-
ities. No additional measures are proposed as part of this wastewater manage-
ment plan.
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LAND USE AND POPULATION CONSIDERATIONS
Project Impacts
One of the most important issues associated with installation of
sewers in the Study Area is the potential effect on growth rates and dis-
tribution patterns. Development patterns are restricted throughout the
Study Area by physical constraints such as flood plains and steep slopes.
In those areas suitable for development, institutional constrains in-
fluence growth patterns. For example, the Colorado Health Department
requires at least three acres of land per dwelling unit in unsewered areas
to accommodate on-site disposal systems. The availability of sewers may
relax this constraint on growth and may facilitate high density growth
and strip development along pipeline alignments. Desired growth patterns
have been adopted by the Planning Commission for four sectors (planning
regions)of the Study Area. However, land use ordinances are subject to
annual review. In view of the competing interest regarding land use manage-
ment practices in the Study Area, the issue of growth facilitation resulting
from sewer installation is considered significant.
The overall impact of sewers on population growth and land use change
in the six Study Areas is variable and depends, in part, on the natural
attractiveness of the areas in question. Without sewers, the development
potential and the relative attractiveness of each area would remain as they
are now. Durango West and the locations near the city but outside the 201/
EIS Study area (Riverside, Hillcrest Mesa and the close-in areas on Florida
Road) would be the most probable high-growth areas, with capacity for
approximately 8,000 of the 20,000 new residents of La Plata County expected
between now and the end of the century. The Hermosa area, another attrac-
tive location, could take another 1,000 to 1,500 residents in the develop-
ment already planned. Edgemont Ranch would be another likely growth area
if and when it develops, with room for an estimated 1,500 residents as
well. Together, these areas would accommodate an estimated 11,000 new
residents, or almost 60 percent of the expected countywide population
increase.
The implementation of a sewer system in the Grandview-Loma Linda
Study Area would have the greatest potential impact on the future dis-
tribution of population and land use, because it would remove a major
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development constraint there. The combination of wastewater facilities
and level, less expensive land (land prices could, however, be expected
to rise) would make the area an attractive one for new development.
If the desired growth pattern is changed to allow higher density develop-
ment, Grandview-Loma Linda could become a high-growth area. It is not
clear whether the increased development potential and attractiveness
in the area would result in a rearrangement of the 11,000 residents
expected to locate in the Durango area of La Plata County or would increase
the area's share of new county residents; Grandview-Loma Linda would be
a feasible alternative for residential location not only to Durango West
and Hermosa but also to Bayfield.
Implementation of projects in other areas would increase the develop-
ment potential but not relative attractiveness of those area. It there-
fore would result in a marginal amount of additional development - primarily
commercial along U. S. Highway 160 in the Lightner Creek area and Waterfall
Village in the West Animas area - but not a significant shift in the dis-
tribution of population growth.
Mitigation Measures
Changes in land use could be minimized by strict adherence to the
desired growth patterns designated in the La Plata County Comprehensive
Plan. Adherence to the plan would channel growth Into existing urban
areas or their peripheries, and would discourage development in rural
areas. However, adherence to land use plans and ordinances is a local matter
and EPA has limited authority over decisions made at the discretion of local
authorities.
SOCIOECONOMIC CONSIDERATIONS
Project Impacts
The issue of who benefits versus who pays is considered significant
for sewering alternatives. Sewers will impose an economic burden on
residents who are presently using satisfactory systems but who will be
required to connect and/or contribute financially to the new sewer system.
The sewering alternatives are designed to correct wastewater management
problems caused by a minority of systems which are operating inadequately.
These problems are generally more acute with package plant operations than
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with individual on-site units. Instead of having owners of faulty systems
paying for the repair/replacement of their own systems, the sewering alter-
natives require all residents in proposed service areas, many of whom have
adequate systems, to support a plan to correct problems created by the
minority.
An additional cost which may affect proposed service area residents
for alternatives which connect to the Durango System would be in the form
of higher taxes resulting from becoming annexed to the City. Connection
to the Durango System would most likely fall under the implied consent rules
of the City. Implementation of sewers, in this case, may represent an
agreement by the residents to be annexed to the City at some future date by
accepting City services.
Indirect long-term effects of the sewering alternatives on the local
economic situation are growth-related. Growth and development intro-
duce new jobs, enlarge the tax base, and probably would result in more
recreationists being attracted to the Study Area. On the other hand,
such growth also entails increased demands on transportation facilities,
urban services, public utilities, and other facilities. These latter costs
are often diffuse and may be at least partially hidden in what appear
to be inflationary increases in property tax, service fees, sales tax,
etc. There have been a number of studies that have "conclusively"
proved both that the economic benefits of growth outweigh the resulting
rise in demand for services, and that the opposite is true. The long-
term economic consequences of growth for any one area are probably highly
dependent on the conditions specific to that area.
Mitigation Measures
No mitigation measures are proposed for socioeconomic impacts.
CULTURAL RESOURCES
Project Impacts
Impacts associated with the project may include the damaging or de-
struction of previously unknown archeological sites by any of the alterna-
tives involving construction of pipelines or new treatment facilities.
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Mitigation Measures
To protect curltural resources from damage associated with construction
of new facilities, the EPA has imposed the following grant conditions:
No payment in excess of 25 percent of the Step 2 grant shall
be made prior to completion of a cultural/historical resources
survey that satisfies the requirements of the construction
grants program. This condition is designed to provide early
identification of any conflicts of the plan with these resources
so that alternatives can be investigated before a major com-
mitment of Step 2 funds has been made.
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TECHNICAL REPORT DATA
jPicasc read Instructions on the r< ivav before completing)
1. REPORT NO. 2.
EPA- 9G8/5-81-C01 B
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Draft Environmental Impact Statement Anpendices
Wastewater Management Plan for the Duranao Area
La Plata County, Colorado
5. REPORT DATE
February 1981
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
John M. Brink, EPA
Gary L. Potter, Engineering Science
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
ENGINEERING SCIENCE, Inc.
2785 North Speer Blvd., Suite 140
Denver, CO 80211
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency, Reoion VIII
1860 Lincoln Street
Denver, CO 80295
13. TYPE OF REPORT AND PERIOD COVERED
Draft
14. SPONSORING AGENCY CODE
8W-EE
15. SUPPLEMENTARY NOTES
Complements Environmental Assessment dated September 10, 1979
16. ABSTRACT ——
Appendix A contains detailed descriptive material and background data on the environ-
mental settinq of the wastewater manaqement plan analyzed in the Environmental Impact
Statement (Report Ho. EPA 90815-81-001A). Appendix B contains additional documenta-
tion of the impact analysis for the study.
17. KEY WORDS AND OOCUMENT ANALYSIS
a DESCRIPTORS
b. 1DENTIF 1ERS/OPEN ENDED TERMS
c. COSATi Field/Group
Sewer Interceptor
Individual Disposal Systems
Privately Owned Small Wastewater Treatment
Systems
Local Land Use Plans
Environmental Impact Statement
City of Duranqo
La Plata County, Colorac
O
18. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (This Report)
21. NO. OF PAGES
20. SECURITY CLASS (This page)
22. PRICE

EPA Form 2220—1 (Rev. 4-77) previous edition is obsolete
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