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Water Conditions - How's the Water
 

How’s the Water?
This will be the twenty six year since the grass carp were first introduced (October 1994) to Lake Mahopac for controlling the Eurasian Milfoil population.  The life expectancy of the sterile carp is about 12 years.  We have continued to perform both the water quality monitoring and vegetation study for Lake Mahopac.  After the Mifoil was gone there were large amounts of filamentous algae growing in place of the Aquatic Plants because of the lack of completion with native plants.  Twenty Years later the Aquatic Plants began to return and filamentous algae was going away. 
 
In 2013 the Biomass found measurable amounts of Eurasian milfoil and other vascular aquatic plant but still under the DEC guidelines of 30%.  In 2016, the plant biomass was at its highest just months prior to the initial restocking of the 200 grass carp in October 2015.  The most recent sampling from the Biomass was conducted on August 26, 2019 at the same sites of the previous years and shows a reduction in Aquatic Plant growth.  The detailed report on 2019 sampling is expected shortly.
 
The grass carp are are reducing the Eurasion Milfoil at the annual sampling sites.  There are other plants that are native (non-invasive) to Lake Mahopac and should not been considered a threat to the lake’s ecosystem.  Aquatic vegetation is a source of (1) food for fish and small insects, (2) protection for breeding fish and (3) oxygen.  A moderate population of aquatic plants (20 to 30%) is essential for the long-term health of the lake.
 
In summary, the amount of grass carp we have are reducing the amount of Eurasion Milfoil from dominating in the lake and the water quality of Lake Mahopac is good.
 
More about Eurasion Milfoil: