Grannis Lake, East Haven - 2011

Grannis Lake is a 19.5-acre lake located in East Haven, CT. The lake is developed on all sides and a road runs along the southern shore. A steep slope leads into the lake on the northern and eastern sides. There is no public boat launch and only electric motors are allowed on the lake. Grannis Lake is primarily used for recreational fishing.

The CAES IAPP 2011 vegetative survey was the second complete vegetative survey conducted on Grannis Lake. The lake was also surveyed in 2004. In 2004, the survey was done after two years of herbicide treatment. Seven species were found. In 2011, the number of species found increased to 18. Three invasive species are present in Grannis Lake: Eurasian watermilfoil (Myriophyllum spicatum), minor naiad (Najas minor), and curlyleaf pondweed (Potamogeton crispus). Curlyleaf pondweed was not found during the August survey, but a preliminary spring survey found the plant growing densely in the lake. Eurasian watermilfoil was found growing in large patches near the shore around the perimeter of most of the lake. Minor naiad was found in medium to small patches close to the shore along the northern side. It was found in large patches along the southern shoreline near the island in the center of the lake. It was also present in the eastern cove. 

There are many native plants growing densely in Grannis Lake as well. Some plants such as white water lily (Nymphaea odorata) and western waterweed (Elodea nuttallii) could be considered reaching nuisance levels. White water lily grew in large patches covering the surface of the lake around much of the perimeter and the shoreline of the island. It grew most dense in the eastern cove. Western waterweed was found growing densely in the deeper areas of the lake where white water lily ended. Coontail (Ceratophyllum demersum) was found growing in extremely high abundance in a large patch along the northern side between the island and the shore. It was also found in lower abundance where many of the other plants were growing. Humped bladderwort (Utricularia gibba) was found in many small patches around the lake.

Species recorded in our 2011 survey of Grannis Lake.
Scientific Names
*Invasive Species
Arrowhead Pickerelweed Spikerush
Common duckweed Sago pondweed Water plantain
Coontail Slender naiad Waterwort
Eurasian watermilfoil* Small pondweed Western waterweed
Humped bladderwort Snailseed pondweed Yellow water lily
Minor naiad* Southern naiad White water lily

Other Grannis Lake Surveys: 2004