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Cayuga Lake

Map of Cayuga Lake
Map of Cayuga Lake

Facts About the Lake

Cayuga Lake is the second-largest of the Finger Lakes of central New York State, extending over 38 miles in length with an average width of 1.75 miles. It is one of the deepest of the Finger Lakes, with a maximum depth of 435 feet. The watershed draining into Cayuga Lake is the largest of the Finger Lakes, covering 785 square miles (approximately 500,000 acres) in parts of 6 counties (Cayuga, Tompkins, Seneca, Schuyler, Tioga and Cortland) and is home to 120,000 people. The watershed consists of agricultural, residential, industrial, and forested land. More than 140 streams flow into the lake along its 95 mile shoreline. The largest of these tributaries includes Salmon Creek, Fall Creek, Cayuga Inlet (including Cascadilla Creek and Six Mile Creek) and Taughannock Creek. Most of the lake is classified as being suitable for use as a drinking water supply (Class AA(T), A(T), or A); a small portion of the lake at the northern/outlet end is Class B(T).

Cayuga Lake and its watershed has been the focus of on-going monitoring by a number of groups, including volunteers through the Statewide Citizen Lake Assessment Program (CSLAP), DEC's Finger Lakes Watershed Program, the Finger Lakes Institute and the Community Science Institute. An additional monitoring study aimed at gaining a better understanding of the factors affecting nutrient loading in the lake, the Cayuga Lake Modeling Project, is also underway. Significant DEC monitoring efforts, Water Quality Study of the Finger Lakes (PDF) and the 2018 Finger Lakes Water Quality Report (PDF), provide a comparison of water quality in all the Finger Lakes.

Aerial view of Cayuga Lake
View of Cayuga Lake - Bill Hecht

The most recent water quality assessment of Cayuga Lake and its tributary waters can be found in Waterbody Inventory Priority Waterbodies List (WI/PWL) fact sheets.

Harmful Algal Blooms (HABs)
Aerial view of the south end of Cayuga Lake and Ithaca
South End Cayuga Lake - Bill Hecht

Cayuga Lake, along with some of the other Finger Lakes, has received considerable attention by state agencies, non-governmental organizations, community interest groups, lake users, water suppliers, and other stakeholders because of the documented presence of HABs in the lake. HABs have been reported to DEC by many data providers including Tompkins and Cayuga County DOH, NYSDOH, trained CSLAP volunteers, and members of the public. For more information about HABs and how to report HABs, please visit DEC's Harmful Algal Bloom webpage. As part of the Governor's HAB initiative a HABs Action Plan was developed for Cayuga Lake.

Invasive Species: Hydrilla

Hydrilla verticillatum (hydrilla, or water thyme) was discovered in Cayuga Inlet in August of 2011. Hydrilla has created significant ecological and economic problems throughout the country and is particularly challenging to control due to abundant and persistent modes of reproduction, spread, and transport. The discovery of this highly invasive aquatic plant In Cayuga Inlet prompted immediate and forceful action, due to the great concern that this plant could move into Cayuga Lake and the Great Lakes ecosystem. A state and local task force was quickly established to delineate the hydrilla populations, identify appropriate management actions, and proceed with an aggressive strategy to eradicate the 166 acre infestation found in the Inlet and some connected waterways, using federal, state, and local resources. Key members of the task force include the City of Ithaca, the Tompkins County Soil and Water Conservation District and Department of Health, Racine-Johnson Aquatic Ecologists, DEC, Canal Corps, and other local and state organizations. Recommendations of the Task Force led DEC to conduct emergency rule-making to allow for a hydrilla infestation treatment effort. The Task Force is engaged in a multi-pronged eradication strategy, including the use of aquatic herbicides, hand removal, boat inspections, and extensive public education, outreach and monitoring. More information about hydrilla in Cayuga Inlet can be found on the Tompkins County CCE website (see link at right).

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