Mamanasco Lake is approximately 86 acres large and is in Ridgefield, CT. The State owns a public boat launch at the southern end of the lake. Only electric motors are allowed on the lake. Much of the shoreline is thickly settled. Along the center western shore there is an exposed cliff line.

The 2012 CAES IAPP survey was a resurvey of Mamanasco Lake.  The first survey was completed in 2005. The 2012 survey found the presence of 11 aquatic species. This has increased from the 4 species found in 2005. The only species found in 2005 not found in 2012 was common water hyacinth (Eichhornia crassipes). The other three species, Eurasian watermilfoil (Myriophyllum spicatum), common duckweed (Lemna minor), and yellow water lily (Nuphar variegata),were all found in 2012 as well. 

The 2012 survey found the presence of 3 invasive species: Eurasian watermilfoil, minor naiad (Najas minor), and curlyleaf pondweed (Potamogeton crispus). Eurasian watermilfoil was found less frequently than in 2005. In 2005, it was found growing in large patches on the north and south end of the lake as well as along most of the east and west shorelines. In 2012, Eurasian watermilfoil was found only in two small patches in the south end of the lake. Minor naiad was found growing in large patches in the southern end of the lake as well as in small patches in the northern end. The highest abundance for this plant was in the south were it would reach the surface of the water. Curlyleaf pondweed was only found in small patches in similar locations as minor naiad. However, curlyleaf pondweed usually grows fervently in the spring months and dies back during the summer. 

The most dominant plant in the lake was a native, small pondweed (Potamogeton pusillus). This plant seemed to take over the areas that the 2005 survey found Eurasian watermilfoil. Small pondweed was found in high abundance around much of the lake. The southern portion had the most dense patch. The plant was growing to the surface and would clog the engine when trying to navigate through it. The next most common species was also a native, coontail (Ceratophyllum demersum). Frequently, this plant was growing in the same locations as small pondweed. Coontail was found growing in the greatest abundance in the southern portion of the lake.