Lake Level - Seneca Lake Pure Waters Association

Seneca Lake is part of the network of lakes, canals and waterways that comprise the Oswego River Basin. The Oswego River Basin drains water from an area of 5,122 square miles, towards Lake Ontario.

Water Flow

Water can flow into Seneca Lake faster than it can flow out. The downstream area is relatively flat and the outflow is regulated; therefore the lake takes longer to drain than to fill. All of the water in Seneca Lake leaves near Geneva through the Cayuga-Seneca Canal. The brown arrows on the map below show the direction of watershed flow. The purple arrows show the direction of the canal flow.

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Seneca Lake Water Level Extremes

April 26, 1993 – 448.95 ft (Record High)

June 25, 1972 – 448.85 ft

March 14, 1978 – 442.64 ft (Record Low)

Lake Level Charts

National Weather Service Geneva Gage (GNVN6)

NYS Canal Corporation Lake Level Chart

Seneca Lake Level Annual Comparisons

Flow Management of Seneca Lake

Seneca Lake’s outflow is managed by Relevate Power (formerly Gravity Renewables), which operates hydroelectric power plants in Waterloo and Seneca Falls. Their goal is to generate clean energy while complying with federal regulations.

Water from Seneca Lake exits through the Cayuga-Seneca Canal, where flow is measured at a river gauge near the Rt-89 bridge in Seneca Falls. The New York State Canal Corporation also manages a small bypass gate and canal locks to ensure safe navigation downstream toward Lake Ontario.

Lake levels are guided by the Seneca Lake Rule Curve, developed in the 1970s, which defines acceptable high and low limits. These targets help balance water levels to prevent flooding or drought, while supporting recreation and protecting natural resources.

Summer Target: 446.0 ± 0.3 ft (reached by mid-March)

Winter Target: 445.0 ± 0.3 ft (reached by mid-December)

Lake Depths and Elevations

Each lake has a rules curve to guide its water level management. But there is only voluntary coordination among the lakes to manage both lake level and water discharge from each lake. Since each management unit has different objectives there are occasional conflicts.