The Chautauqua Lake Watershed drains an area of Chautauqua County in southwestern New York State. The long and narrow lake is comprised of a North Basin and South Basin, which together span 16 miles. The North Basin has an average depth of 26 feet, whereas the South Basin has an average depth of only 11 feet. The lake’s outlet is located at the eastern end of the South Basin, where it flows through the Chadakoin River and Cassadaga Creek and empties in the Allegheny River, a major tributary of the Ohio River, which eventually drains into the Mississippi River and the Gulf of Mexico.
Watershed Facts and Uses:
- Area: 115,349 acres
- Lake Area: 13,422 acres
- Shoreline Length: 43 miles
- Elevation: 1308 feet above sea level
Chautauqua Lake is a popular summer destination for swimming, boating, and fishing. Public beaches and boat launches are available at a number of parks along the lake’s shoreline. Chautauqua Lake is a Class A waterbody and is used as a source of drinking water for lake residents and visitors, including more than 100,000 visitors to the Chautauqua Institution each summer.
Water Quality Problems and Solutions
Excess nutrients (phosphorus) and sediment from all over the Chautauqua Lake watershed degrade the lake’s water quality. Nutrient sources include sewage, manure, inorganic fertilizer, urban stormwater and sediment-bound phosphorus from eroded streambanks, fields, and rural roads.
Chautauqua Lake Phosphorus Total Maximum Daily Load
In 2012, the US Environmental Protection Agency (USEPA) approved the Total Maximum Daily Load (TMDL) for Phosphorus in Chautauqua Lake. The TMDL outlines the maximum amount of phosphorous pollution that the lake can receive and still meet water quality standards.
The TMDL established the necessary reductions in phosphorous for each wastewater treatment facility (WWTF) located along the lake as well as quantifying reductions needed from agriculture, developed land, septic systems, and internal loading.
There has been significant effort to address phosphorous sources in the watershed, including comprehensive upgrades at WWTFs to meet more stringent discharge requirements and construction of sewer extensions to take aging and failing septic systems out of service. Non-point source pollution from agriculture is addressed by the Chautauqua County Soil and Water Conservation District (SWCD) through an Agricultural Environmental Management (AEM) program, as well as through DEC’s General Permit for Concentrated Animal Feeding Operations (CAFOs).
Chautauqua Lake Harmful Algal Bloom Action Plan
Harmful algal blooms (HABs) have been of concern in recent years due to increased frequency and duration in blooms. NYSDEC, along with the New York State Department of Health (NYSDOH) and New York State Department of Agriculture and Markets (NYSDAM), developed a Harmful Algal Bloom Action Plan for Chautauqua Lake in 2018 to identify conditions that contribute to the formation of HABs and determine immediate and long-term actions to reduce their frequency.
Aquatic Plants
Since 2019, DEC has issued annual permits for aquatic herbicide applications to address two invasive weed species that are prevalent in the lake: curly leaf pondweed and Eurasian milfoil. DEC performs field verification of the areas to be treated prior to application. The permit requires notification to all property owners in affected areas. Updates and notifications are also provided to the public through DEC’s Chautauqua Lake Listserv.
2024 Permits
Note: Acreage that has not been approved to date this year, are areas that have been deemed critical fish habitat. There are seven acres in the town of Ellery that have been permitted, but not treated, due to the target vegetation (Curly-leaf pondweed) not being present at the time of treatment.
Curly-leaf Permits
- Town of Ellery permit #AV92024-032, requested to treat 105 surface acres for curly-leaf pondweed with Aquathol K, EPA #70506-176. They were permitted for 51.5 acres and ended up treating 44.5 acres on April 25, 2024, at a dosage rate of 1 ppm.

- Town of Busti permit #AV92024-033, requested 220 surface acres for curly-leaf pondweed with Aquathol K, EPA #70506-176. They were permitted for 160 acres and treated 160 acres on April 25, 2024 at a dosage rate of 1 ppm.

Starry Stonewort Permit Applications
- Town of Ellicott is requesting two permits to treat starry stonewort. One permit application is for Captain, EPA #67690-9, to treat six surface acres at a dosage rate of 0.8 ppm. The second permit application is for Komeen Descend, EPA # 67690-25, to treat 6.3 acres at a dosage rate of 0.75 ppm.
- Village of Lakewood is requesting one permit to treat starry stonewort with Nautique, EPA #67690-10, to treat 6.5 acres at a dosage rate of 0.8 ppm.
Both are under review. Anticipated treatment date is now sometime in July. Permit applicants have to renotify riparian owners/users regarding water use restrictions, which is a drinking water restriction until copper concentration is 200 ppb or less.
Eurasian Watermilfoil Permit Applications
All applicants requested ProcellaCOR EC, EPA #67690-80, at a dosage rate of 3.98 ppb. The treatment date for each was Monday, June 24.
- Camp Chautauqua requested 11 acres and was permitted 11 acres. This area was not treated because a pretreatment survey found it to be unnecessary.
- Sunrise Cove Association requested 14.3 acres and was permitted 11.5 acres. The permitted 11.5-acre area was treated on June 24th.
- Town of Ellery requested five treatment areas for a total of 81.6 acres. DEC permitted 23.68 acres within the five proposed treatment areas. The Town of Ellery decided to only treat two of the permitted areas for a total of 15.4 acres. See below maps of intended treatment areas.
- Town of Busti requested three treatment areas for a total of 129 acres. 101.6 acres was permitted within the three treatment areas. One 35-acre area was not treated because a pretreatment survey found it to be unnecessary.
- Town of Ellicott requested two treatment areas for a total of 101 acres. All 101 acres was permitted and treated on June 24th.
A PDF Map of the Eurasian Water-Milfoil Treatment Areas North (PDF) and South (PDF) .
Village of Celeron Nuisance Vegetation Permit
Requested to treat two areas for pondweeds, milfoil, and coontail with Komeen Descend, EPA #67690-25, 12.5 acres in total at a dosage rate of 0.75 ppm. Proposed treatment areas are near the Chautauqua Harbor Hotel and the marinas along the outlet of the lake. New permit applications have been received and are under review.
See a map of the combined starry-stonewart treatment areas and the hotel/marina proposed areas.
Chautauqua Lake Watershed News and Updates
Access the summer 2024 Fact Sheet (PDF) that includes updates about the Freshwater Wetlands Act.