Water Quality Improvement Project
Lake Chelan is located in north-central Washington State. It is the longest
and deepest natural lake in the state. Lake Chelan collects water from a
watershed that is 924-square-miles. Ninety percent of the watershed is forested
or open lands, with the majority managed by the United States Department of
Agriculture’s Forest Service (USFS) and the National Park Service. The lake
itself occupies two distinct basins: the northwestern Lucerne Basin and the
southeastern Wapato Basin. Lands used for agriculture and orchards comprise
three percent of the watershed’s land area, almost all located in the more
developed area surrounding the Wapato Basin. A cluster of three small lakes:
Roses Lake, Wapato Lake and Dry Lake, are located about a mile north of the town
of Manson and drain to Lake Chelan.
Water quality issues
Persistent, man-made chemicals, a legacy of past agricultural and industrial
activities, contaminate the sediment, water and fishes in Lake Chelan and Roses
Lake. These toxins are the pesticide DDT and its associated breakdown products,
as well as polychlorinated biphenyls (PCBs). Federal and state governments
banned the use of these toxins more than 25 years ago, but they still persist in
water, land and fish in the Lake Chelan watershed today. The improvement of Lake
Chelan’s sediment, water quality and fish will depend on minimizing the movement
of these contaminants from the surrounding lands to the lake and its
tributaries. This Water Quality Implementation Plan addresses 303(d) listings
for DDT and PCBs in fish tissue in Lake Chelan and Roses Lake.
DDT and PCB compounds enter Lake Chelan and Roses Lake and accumulate in the
tissues of the fish living in these waters. The levels of these chemicals in the
tissue of burbot, kokanee and lake trout exceed federal and state water quality
standards set to protect human health. The state of Washington completed a Water
Quality Improvement Report (WQIR), also known as a Total Maximum Daily Load
(TMDL), to address these contaminants in the fish of Lake Chelan and Roses Lake.
Why this matters
Dichloro-Diphenyl-Trichloroethane (DDT) is a colorless, odorless,
chlorinated insecticide that is water resistant. It tends to accumulate in
sediment, plants, aquatic plants and animals, and fish. DDT is regularly found
in waters near fruit orchards. It was widely used from the mid-1940s until 1958,
when the U.S. Department of Agriculture (USDA) began a program to phase it out
for its insect control programs due to concerns about its persistence in the
environment and toxicity to non-target organisms, such as aquatic life. In 1972,
the U.S. Environmental Protection Agency (EPA) banned DDT for all uses except
Despite the ban, DDT persists in the environment. Soils containing DDT can
end up in streams and other surface water bodies through erosion. As DDT is
transported to streams, it is absorbed by the plant and animal life within the
stream system and then moves up the food chain. DDT biomagnifies at higher
levels in each step of the food chain (plants, aquatic biota, fish, humans). DDT
can also be found in ground water, as water infiltrates through contaminated
soils into aquifers.
Pesticides and polychlorinated biphenyls (PCBs) can be toxic to fish
and wildlife that use a contaminated water body.
In the past, PCBs were used as coolants and lubricants in electrical
equipment such as transformers and capacitors. The United States banned the
manufacture of PCBs in 1977 because they build up in the environment and can be
harmful to humans and wildlife. PCB exposure can occur if you:
- Eat food, including fish, meat, and dairy products that is contaminated
- Drink PCB-contaminated water.
- Breathe air near hazardous waste sites that contain PCBs.
Phosphorus fuels the growth of algae. When algae die, they remove
oxygen from the water. Fish and aquatic life need oxygen to survive.
Status of the project
Residues of DDT persist in soils where it was applied, most often on
agricultural lands. These residues move with soils when erosion occurs. DDT can
also move through the soil profile to ground water during irrigation, snowmelt,
and rain events. The most practical means to minimize the additions of DDT to
the lake are taking steps to minimize (1) soil erosion to surface water and (2)
DDT transport through the soil profile to ground water from the agricultural
Many actions were taken to reduce the input of DDT and PCB contamination in
the environment. DDT and PCBs were both banned in 1970s, which established the
beginning of environmental recovery. Reduced soil erosion and improved
management of riparian lands also contributed to the reduction of DDT in the
Lake Chelan watershed. Regulatory restrictions, as well as collection and
disposal of old PCB electrical equipment, reduced the quantity of PCBs entering
Additionally, the Lake Chelan Watershed DDT and PCB TMDL Water Quality
Improvement Report identified several actions to reduce inputs of these legacy
pollutants to Lake Chelan and Roses Lake. Water quality standards for DDT and
PCBs in fish tissue are expected to be met by 2055. Milestones will be
established and evaluated along the way.
Management activities target primarily DDT. However, PCB actions are being
implemented, such as education, PCB transformer recycling, cleanup of old PCB
sites, pesticide pickup days, etc. PCBs levels will also be followed.
- The Lake Chelan Watershed DDT and PCB TMDL Water Quality Improvement
Report was approved by EPA on September 11, 2006.
- The final Implementation Plan was submitted to EPA on
August 5, 2008.
- Lake Chelan Total Maximum Daily Load for Total Phosphorus was approved by
EPA January 26, 1993.
Unless otherwise specified, the following documents are Ecology publications.
WA Dept. of Health Lake Chelan Fish Consumption Advisory Fact Sheet #334-082.
Reducing Phosphorus Pollution to Improve Water Quality (Water Quality
WRIA 47: Chelan Watershed Information (Environmental Assessment
Program web site)
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Last updated August
WRIA(s): #47 (Chelan)
# of TMDLs:
DDT/PCB - 5
Phosphorus - 1
DDT/PCB - Approved by EPA, has implementation plan
Phosphorus - Approved by EPA, has implementation plan
Department of Ecology
1250 West Alder Street
Union Gap, WA 98903-0009