United States
                    Environmental Protection
                    Agency
                           Office Of Water
                           (4503F)
                         EPA841-F-94-001
                         January 1994
                         Number 7 7
                    TMDL    Case   Study
                    Lake   Chelan,   Washington
Key Feature:
Project Name:
Location:

Seope/Si/e:
Land Type:
Type of Activity:
Pollutants:
TMDL Development:
Data Sources:
Data Mechanisms:
Monitoring Plan:
Control Measures:
A phosphorus TMDL to protect a
threatened lake

Lake Chelan
EPA Region X/Chelan County,
Washington
Lake, watershed 2,393 km2
Ecoregion 10, high mountains
Forest, agriculture, urban
Phosphorus, bacteria
PS, NPS
State and local
Steady-state model
Yes
Increased public sewerage,
development limits, boat sewage
pump-outs, agricultural and
stormwater management
        Washington State
Puget Sound
                                                   FIGURE 1.  Location of Lake Chelan in central Washington
Summary: Lake Chelan, located in the Northern Cascades of central Washington State (Figure 1), is classified as ultra-
oligotrophic.  It has extremely low nutrient levels and a high degree of clarity.  Although it is not on Washington's 303(d)
list, increasing development pressures have raised concerns about maintaining the lake's high water quality. During 1989,
in an effort to protect this unique and highly valuable natural resource, the Washington State Department of Ecology
(DOE) conducted the Lake Chelan Water Quality Assessment which determined the nutrient loading limits that will
maintain the lake's ultra-oligotrophic condition.

In 1990, the Lake Chelan Water Quality Committee, which is composed of representatives from local public-agencies,
prepared a water quality plan based on the assessment.  The plan included a list of action items for controlling nutrients
and bacteria from 6n-site septic systems, underground sewer lines, agricultural runoff, and urban stormwater runoff. The
water quality plan also included a TMDL for total phosphorus in Lake Chelan.  To support the Committee's effort, DOE
conducted the technical TMDL analyses for several options, based on potential development patterns in different portions
of the basin. The most-likely option was chosen and a phosphorus TMDL of 51 kg/day was submitted to and approved by
EPA Region X. The TMDL includes load allocations of 0.5 kg/day for future growth, 6.3 kg/day for existing sources,
and 44.2 kg/day, for background loads (Pelletier, 1991).  The Lake Chelan Water Quality Committee is responsible for
implementing the water quality plan in order to meet the TMDL. The committee is currently investigating various control
approaches such as sewer line replacement, sewer system extension, boat sewage pump-out facilities, agricultural runoff
management, and stormwater management.
  Contact:   Steve Butkus, Washington State Department of Ecology, Water Quality Program, PO Box 47600,
            Olympia, Washington 98504-7600, phone (206)407-6482
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 BACKGROUND

 Lake Chelan is located in the northern Cascades,
 approximately 100 miles east of Seattle and 50 miles
 south of the Canadian border.  Lake Chelan serves as a
 water supply for more than 6,000 residents, provides
 irrigation water for approximately 18,000 acres, and
 produces hydroelectric power (Beck and Assoc., 1991).
 It is also an important location  for water-related
 recreation  and fisheries production. It is considered one
 of the most pristine bodies of water in North America,
 with a high degree of clarity and extremely low nutrient
 levels.

 Lake Chelan is over 50 miles long with an average width
 of 1 mile.   It has a surface area of 52 mi- (134 km2) and
 a watershed of approximately 924 mi2 (2393 km2).  Lake
 Chelan discharges to the Chelan River at a small
 hydroelectric dam in the city of Chelan (Figure 2).  The
 dam, which was constructed in  1927, raised the level of
 the lake by 24 feet.  Beyond the dam, the Chelan River
 flows only a few miles before emptying into the
 Columbia River. The average annual discharge from
 Lake Chelan is 2,050 cubic feet per second (cfs); its
 bulk detention  time (i.e., the average amount of time it
 takes for the all of the water in  the  lake to be
 exchanged) is  approximately 10.6 years (Patmont et al.,
 1989).

 Lake Chelan has two distinct basins, which are
 distinguished mainly by their bathymetry. The upper
 basin is extremely deep and approximately 38 miles in
 length.  The maximum recorded depth is  1,486 feet
 although some  local residents maintain that the lake "has
 no  bottom." The lower basin, which is bordered by the
 city of Chelan, is approximately 12  miles long and has
 an average depth of approximately 141  feet (Patmont et
 al.,  1989).

 The upper basin is very remote  and  accessible only by
 boat or plane.   Consequently, the vast majority of its
 watershed remains heavily wooded and undisturbed.
 Most of the watershed is public land, including the Lake
 Chelan National Recreation Area, the Sawtooth
 Wilderness, the Wenatchee Forest, and portions of the
 North Cascades National Park and Glacier Peak
 Wilderness. Land use in the lower watershed is a
 mixture of  forest, apple orchards,  and urban land.
Table 1 summarizes the distribution  of land uses in the
watershed as a whole.

The total resident population of the Chelan basin was
approximately 6,600 in 1987. However, the population
changes seasonally due to fluctuations in the farm labor
force, tourism,  and recreation.  Nearly all of the
residents live in the lower basin, primarily in the city of
Chelan and the  town of Manson.   In the upper basin,
                                               Chelan
  FIGURE 2.  Schematic of the Lake Chelan watershed

 approximately 130 people live in the villages of
 Stehekin, Lucerne, and Holden.  Between  1910 and
 1950, a mine operated in the Holden area and the upper
 basin was more populated. The lower basin reported a
 12.5 percent population increase between 1970 and
 1980, a growth rate that is likely to continue or increase
 in the future because of the basin's recreational appeal
 (Patmont et al.,  1989).
 ASSESSING AND CHARACTERIZING
 THE PROBLEM

 Targeting and Prioritizing

 Identifying and protecting threatened good-quality waters
 are important to the TMDL program.  Although Lake
 Chelan is not currently classified as water quality-limited
 and does not appear on Washington's 1992 section
 303(d) list, there is concern that, without comprehensive
 planning, increasing development in the watershed  could
 degrade water quality.  It is for this reason that, in
 April, the Lake Chelan Water Quality Committee
 developed a phosphorus TMDL for Lake Chelan.

 Monitoring  and Data

 In 1989,  Washington's Department of Ecology (DOE)
conducted the Lake Chelan Water Quality Assessment.
This intensive study was designed to (1) provide baseline
water quality data; (2) evaluate the suitability of on-site
wastewater disposal systems within the developing lower
basin; and (3) estimate the potential sources and impacts
of nutrients, bacteria, and other chemicals of concern.

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T&BL.E 1.  Land use within the
(Patmontet al., 1989)
Lake Chelan watershed
Land Use
Lake Chelan
Other Water Bodies
Forested Public Lands
Forested Private Lands
Agriculture - Orchard
Agriculture - Nonorchard
Residential
Roadways
Commercial and Public Buildings
TOTAL
Area
(mi-)
52
1.5
772
63
18
12
2.3
2.3
0.38
923.9
Percent of
Total
5.6
0.2
83.9
6.8
2.0
1.3
0.3
0.2
0.0
100
 The State's report detailed the lake's present condition
 and supplied most of the technical information for
 developing this TMDL (Patmont et al., 1989). Table 2
 summarizes the lake's water quality characteristics for
 several parameters of concern.

 Phosphorus

 Phosphorus is the principal nutrient controlling algal
 growth in Lake Chelan.  This was determined through
 analysis of water column and particulate matter nitrogen-
 to-phosphorus ratios (Table 2).  Both ratios indicated
 that phosphorus is the nutrient limiting algal growth.

 The Lake Chelan Water Quality Assessment estimated
 that from 75 to 90 percent of the phosphorus input to the
 lake comes from natural sources, largely forest runoff
 and direct precipitation.  Of the remaining 10 to 25
 percent attributable to anthropogenic sources,  roughly
 half comes from agricultural activities, primarily
 orchards.  A large portion of the total agricultural runoff
 loads are attenuated in three small lakes located in
 orchard areas approximately 1 mile north of the lake's
 north shore. However, loading values associated with
 the runoff from orchard operations have not been
 quantified (Beck and Assoc., 1991).

 The remaining phosphorus loads in the basin are
 attributable to stormwater runoff and  septic system
 inputs (Patmont et al., 1989).  Homes using on-site
 waste disposal contribute approximately 0.08 kg
 P/day/1,000 homes.  This  includes phosphorus from the
 septic system and from lot runoff.  Homes on public
 sewer systems are estimated to contribute only to the
 runoff component, or 0.001 kg P/day.
Chinook salmon net pens are the only point source of
phosphorus in the watershed. Net pens are large,
floating, barge-like structures that contain dense
populations of fish being raised for market.  The fish,
which are fed with special preprocessed  food packs, are
estimated to contribute 0.01 kg  P per day per 2,000 Ib
offish (Beck and Assoc., 1991).

Bacteria

In addition to phosphorus enrichment, pathogens from
septic systems pose a health concern  for those who use
the lower basin as a source of drinking water.  At the
lake outlet, fecal streptococcus, fecal coliform, and total
coliform are within state and federal  criteria for water
contact  recreational use; however, values do regularly
exceed the State's potable water standard of
1 count/100 ml (Patmont et al., 1989).  The Chelan-
Douglas Health District chlorinates water prior to
distribution.

The Management Plan

In 1990, the  City of Chelan,  Chelan  County, the Chelan
County Public Utility District, the Lake Chelan Sewer
District, and  the Lake Chelan Reclamation District
formed the Lake Chelan Water  Quality Committee.
With funding from the .Washington Centennial Clean
Water Fund, the Committee prepared the Lake Chelan
Water Quality Plan, which specifies steps to ensure that
Lake Chelan maintains its present ultra-oligotrophic
status.   Since urbanization is a major concern in the
watershed, the plan's primary .recommendations are to

TABLE 2.  Average spring/summer values for  selected
water quality parameters for Lake Chelan, Washington
Parameter
Secchi Disk Depth (m)
Temperature (°C)
pH
Dissolved Oxygen (mg/L)
Total Suspended Solids (mg/L)
Sp. Conductance (umho/cm)
Total Phosphorus (ug/L)
Total Nitrogen (ug/L)
Total Coliibrm (0/100 ml) .
Particulalc N:P
Water Column N:P
Average
Epiliihnetic Value
(95% CI)
12.1 +/- 0.5
13.2 +/- 0.4
7.67 +/- 0.02
10.6 +/- 0.1
0.1 +/-0.0
56.7 +/-0.1
3.01 +/- 0.18
103 +/- 6
2.2 +/- 0.5
> 15:1-
30:1 +/- 3:1

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 expand existing sewerage facilities and to extend services
 to presently unsewered areas.  Specific concerns are as
 follows (Beck and Assoc., 1991):

 Qn-site wastewater management - Older on-site systems
 may not perform satisfactorily.  For certain situations,
 hookup to public sewers may become mandatory.

 Stormwater management - Runoff from newly developed
 areas may increase pollutant loadings to the lake.  New
 ordinances for stormwater and  drainage standards are
 being developed.

 Agricultural activities - Runoff from agriculture impacts
 the lake; monitoring to determine potential impacts may
 be considered, as may improved farmer education  and
 the increased development of farm plans.

 Boat sewage disposal - As boat recreation increases,  so
 will potential for pollution. A task  force to develop an
 improved program for regulation and education,
 additional  facilities, and new licensing provisions have
 been proposed.
TMDL DEVELOPMENT

The goal is to preserve the ultra-oligotrophic condition
of Lake Chelan.  Additional total phosphorus (TP)
loadings to the lake (over the 1986-87 load) are
considered acceptable only if there is less than a
5 percent chance that such additions will cause in-lake
(lower basin) TP concentrations to exceed 4.5 /tg/L,
which is &  generally accepted value for the  ultra-
oligotrophic classification.  Management goals are
expressed in terms of their effect  on the lower basin
because the lower basin is relatively shallow and
consequently more prone to the effects of increased
phosphorus loads. DO& conducted these analyses as
technical support for the Lake Chelan Water Quality
Committee's water quality plan.

Using a steady-state mass balance model and Monte
Carlo analysis techniques, DOE calculated that the 4.5
/
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TABLE 3.  Summary of load allocation strategies for future development in the upper and lower basins of Lake Chelan
(Pelletier, 1991)                                                                                .

OPTION 1:
No growth in
upper basin
OPTION 2:

Mixture of growth
in upper and
lower basins





OPTION 3:
No growth in
lower basin
LOAD ALLOCATIONS (kg P/day)
Existing (1986-87)
land uses in lower
basin

6.3

6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6,3

6.3
Future. growth in
lower basin

0.50

0.47
0.45
0.40
0.34
0.29
0.24
0.19
0.14
0.08

0.00
Future growth in
the upper basin

0.00

0.05
0.10
0.20,
0.30
0.40
0.50
0.60
.0.70
0.80

0.96
Background load
from upper basin
watershed and
precipitation

44.2

44.2
44.2
44.2
44.2
44.2
44.2
' 44.2
44.2
44.2 '

44.2
TMDL

- 51.0

51.0
51.0
51.1
51.1
51.2
51.2
51.3
51.3
51.4

5'1.5
Wengreen, Public Utility District #1 of Chelan County,
personal communication, September 22, 1993):

Wastewater treatment - Although the Chelan Treatment
Plant discharges into the Columbia  River, the collector
pipe for the Lake Chelan Sewer District runs under the
lake shore.  This has sparked significant water quality
and health concerns.  Negotiations are underway
regarding the replacement of the sewer collector line for
the district.

Stormwater - Proposed regulations for stormwater
management are currently being developed by the City
of Chelan and Chelan County.

Boat Sewage - One new boat sewage pump-out station
has been installed, bringing the total in the lake to three.
Additional, pump-outs are being  investigated.
 LONG-TERM MONITORING

 The Lake Chelan Water Quality Plan includes a long-
 term water quality monitoring strategy.  The plan states
that permanent stations will be chosen and selected
parameters will be monitored on a repeating year cycle.
This has not yet occurred; however, the Lake Chelan
Reclamation District has received a $176,000 grant
(75 percent cost share) to initiate a short-term "Irrigation
Water Management and Drain Monitoring" project in the
watershed.

The drain monitoring portion of the plan will assess
water quality trends and. runoff from agricultural drains
to evaluate pollutant loading during worst case
conditions. At  a minimum, the following parameters
will be evaluated:  flowi fecal coliform, total suspended
solids, turbidity, dissolved oxygen, temperature, pH,
TP, ammonia nitrogen, nitrites, nitrates, and
conductivity.  DOE also conducts monthly TP sampling
at the lake outlet.

The irrigation water management portion of the project
will involve extensive soils analysis to determine the
optimum procedure for managing irrigation rate, timing,
and duration. The goal is to help growers minimize the
amount of water leaving the site either through runoff or
deep percolation (DOE, 1993).

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TABLE 4. Load allocations for four Lake Chelan development scenarios (Beck and Assoc., 1991)
   Scenario 1:     Sewer system extended,  but proportion of homes on septic remains the same

           This scenario assumes that net pens remain at their current size, agricultural lands do not increase in size, and
           the percentage of homes on septic systems remains the same.
           Source Type

           Homes using on-site disposal
           Homes on sewer systems
           Chinook net pens
           Agricultural activities
Allowable Load

0.16 kg P per day
0.33 kg P per day
0.01 kg P per day
0.00 kg P per day
Development Potential

800 new residential units
3,300 new residential units
2000 Ib of fish (existing)
No additional acres
   Scenario 2:     Comprehensive sewerage

           This scenario assumes that a comprehensive sewer plan is developed and implemented.  This would result in
           the construction of very few, if any, on-site sewer systems in the future.
           Source Type

           Homes on sewer systems
           Chinook net pens
           Agricultural activities
Allowable Load

0.49 kg P per day
0.01 kg P per day
0.00 kg per day
Development Potential

4,900 new residential units
2,000 Ib of fish (existing)
No additional acres
   Scenario 3:     Sewer systems not extended

           This scenario assumes that sewer systems are not expanded beyond their current service areas and that sewered
           homes are built until the capacity of the treatment plant is reached.
           Source Type

           Homes on sewer systems
           Homes with on-site disposal
           Chinook net pens
           Agricultural Activities
Allowable Load

0.23 kg P per day
0.26 kg P per day
0.01 kg P per day
0.00 kg per day
Development Potential

2,300 new residential units
1,440 new residential units
2000 Ib of fish (existing)
No additional acres
   Scenario 4:      Agricultural land converted to home sites

           This scenario assumes that some agricultural lands are converted to home sites.  This is considered highly
           probable and will likely occur in conjunction with any of the first three scenarios.
           Conversion to homes with sewer systems
           Conversion to homes with on-site septic systems
                1 additional home for every 0.24 acre converted
                1 additional home for every 2.0 acres converted

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TABLE 5.   Summary of required actions  (Beck and
Assoc., 1991)'
Agency/ Action Item
WQ Advisory Committee
• Plan approval
• Expand and formali/.e committee
• Establish boat sewage task force
• Submit sewer hookup ordinances .
• Establish on-site wastewater task
force
• Submit stormwater ordinances
• Submit amended boat registration
rates
City of Chelan
• Prepare stormwater management plan
• Construct interim facilities
• Relocate primary facilities and
expand wastewater plant
Chelan Public Utility District
• Relocate interceptor
• Construct lakeside/primary plant
. interceptor
• Construct Minneapolis Beach/Yacht
Club interceptor
• Construct Yacht Club/Fields Landing
interceptor
Chelan County
• Prepare stormwaler management plan
Lake Chelan Reclamation District
• Extend sewer past Willow Point
Chelan County Conservation District
• Conduct agricultural drain monitoring
• Prepare farm plans
Washington State Parks
• Construct 25 Mile Creek wastewaler
facilities
WSU Cooperative Extension
• Establish education programs for
growers
Chelan County Fire Marshall
• Survey storage lank practices
Cost
($ 1990)
	 A
	 t)
	 a
a
	 A
150,000
350,000
6,700,000
3,500,000
850,000
4,630,000
3,620,000
150,000
1,390,000
75,000
2,160,000
	 A
	 "
REFERENCES

Beck, R.W., and Associates.  1991. Lake Chelan water
quality plan.  Report to the Lake Chelan Water Quality
Committee, Wenatchee, Washington.

DOE.  1992. Lake Chelan TMDL summary.  TMDL
Number 47-001. Washington State Department of
Ecology, Olympia, Washington.

DOE.  1993. Centennial dean water fund grant
agreement between the State of Washington Department
of Ecology and Lake Chelan Reclamation District.
Washington State Department of Ecology, Olympia,
Washington.

Patmont, C.R., G.J.  Pelletier, E.B. Welch, and C.C.
Ebbesmeyer.  1989.  Lake Chelan water quality
assessment.  Prepared by Harper Owes, Inc. for
Washington State Department of .Ecology, Olympia,
Washington.

Pelletier, G.  1991.  Lake Chelan TMDL for total
phosphorus.. Memorandum of April 5  to B.  Hashim and
J. Milton. Washington State Department of Ecology,
Olympia, Washington.

USEPA.   1991.  Guidance for water quality-based
decisions: The TMDL process.  EPA 440/4-91-001.
United States Environmental Protection Agency, Office
of Water, Washington, DC.
                                                              This case study  was prepared by Research Triangle
                                                              Institute, Research Triangle Park, NC, in conjunction with
                                                              EPA,  Office  of  Office of  Wetlands,  Oceans,  and
                                                              Watersheds, Watershed Management Section.  To obtain.
                                                              copies,  contact  your  EPA   Regional  303(d)/TMDL
                                                              Coordinator.
  Funds from each agency's ongoing programs.

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