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Environmental Information

The Lake Mahopac Park District proposes to stock Lake Mahopac with Triploid Grass Carp (a sterile fish) for the purpose of controlling nuisance levels of submerged aquatic vegetation.  A Full Environmental Impact Statement was conducted by the Park District in 1993, and the Department of Environmental Conservation (DEC) issued a permit to stock Triploid Grass Carp.  Following the stocking of 2,565 Triploid Grass Carp in 1994, Eurasian Watermilfoil (a nonnative invasive aquatic plant) was eradicated from the lake.  Over the last several years, native aquatic vegetation has returned, which should be a benefit for the ecology of the lake.  Unfortunately, a relatively small amount of Eurasian Watermilfoil has also returned.  The Park District would like to stock additional Triploid Grass Carp to hopefully reduce the amount of Eurasian Watermilfoil before it starts to expand to the levels it had attained in the early 1990s.  New York State DEC has reviewed the Park District’s stocking permit application and plans to issue a permit for the Park District to stock up to 170 Triploid Grass Carp.  The Park District will continue to monitor the aquatic plant life in Lake Mahopac to help evaluate the results of this stocking.  DEC would like to receive comments from people interested in this issue.  Please send comments by April 3, 2015 to: Michael Flaherty, NYSDEC Fisheries, 21 South Putt Corners Road, New Paltz, NY 12561, 845-256-3066,
  1. Algal Blooms
  2. Flotsam or Debris in the lake
  3. Invasive Species
  4. Aquatic Vegetation management
  5. Geese Management
  6. Water Conditions - How's the Water
  7. Annual Draw Down
  8. Lake Friendly Fertilizer
  9. Research on Lake Mahopac performed by  Morgan Giannetta and Kayleigh Dzuiba
  10. Known Aquatic Invasive Species in lower Hudson Valley