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 TMDL Watershed Implementation Plan Development
Despite these efforts, Chautauqua Lake is still not meeting the target total phosphorus concentration assigned by the TMDL of 20 ug/L. As a result, DEC is developing a TMDL Watershed Implementation Plan to work on achieving the TMDL phosphorus target concentrations in Chautauqua Lake. TMDL Watershed Implementation Plans are part of NY's adaptive management strategy to reduce phosphorus pollution in receiving waters. The plan will be developed in three phases.
Phase 1 - Data collection including an Internal Loading Study and Stakeholder Outreach
Ramboll has been contracted to design and carry out an internal loading study with a subcontract to the Upstate Freshwater Institute. This study will quantify the magnitude and extend of internal loading throughout both basins of Chautauqua Lake. Learn more in the Chautauqua Lake Internal Loading Study fact sheet (PDF).
DEC will work with local stakeholders to identify specific problem areas on land with high potential of phosphorus loading and projects that could be implemented to address those sources.
Phase 2 - Drafting of the TMDL Watershed Implementation Plan
The TMDL Watershed Implementation Plan will include a thorough desktop analysis of the watershed looking at how land-use and phosphorus load distribution might have changed since the development of the 2012 TMDL as well as the examining the data collected during phase 1.
Phase 3-Reviewing the TMDL Watershed Implementation Plan
Phase 3 will include multiple levels of internal review and a public comment period on the draft TMDL Watershed Implementation Plan.
Learn more about the plan details in the Chautauqua Lake TMDL Watershed Implementation Plan fact sheet (PDF).
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.
2025 Permits
Curly-leaf Permits
The Towns of Ellery, Ellicott, and Busti are requesting aquatic vegetation permits to treat curly-leaf pondweed with an aquatic herbicide called Clearcast, EPA # 241-437-67690. The requested acreage for each town is:
Town of Ellery – 212.5 acres
Town of Ellicott – 90 acres
Town of Busti – 161 acres
Eurasian Watermilfoil Permits
The Towns of Ellery and Ellicott are requesting aquatic vegetation permits to treat Eurasian Watermilfoil with an aquatic herbicide called ProcellaCOR EC, EPA # 67690-80. The requested acreage for each town is:
Town of Ellery – 102.5 acres
Town of Ellicott – 83 acres
Wetlands in the Chautauqua Lake Watershed
The wetlands in the Chautauqua Lake watershed are valuable to people and the environment. Wetlands have numerous functions and benefits that no other ecosystem can provide, such as preventing soil erosion and flooding. In these times of increased severe storms, this function is particularly important. Wetland vegetation purifies water by filtering sediments and absorbing pollutants from surface waters. Wetlands are home to hundreds of animal and plant species and act as a nursery for young wildlife and fish. Chautauqua Lake is an important home to important freshwater mussels and turtles. Wetlands in the Chautauqua Lake watershed provide a broad variety of recreational opportunities such as waterfowl hunting, muskie and bass fishing, and birdwatching. On January 1, 2025 DEC made changes to freshwater wetland regulation jurisdiction to protect more wetland areas. Access the Chautauqua Lake wetland FAQ (PDF) that includes information about how updates to Freshwater Wetlands regulations will impact Chautauqua Lake stakeholders.
