Photo of Bashan Lake in East Haddam, CT.

Bashan Lake, East Haddam - 2020

Aquatic plant survey map of Bashan Lake in East Haddam, CT.

2020 Aquatic Plant Survey Map of Bashan Lake

Transect Data | Water Data

Bashan Lake is a 273-acre waterbody located in East Haddam, CT. The lake is moderately developed with residential homes along the shoreline and public access through a state boat launch.

CAES IAPP has monitored and treated invasive plants in Bashan Lake for nearly 20 years. Previous aquatic plant surveys for all native and invasive plants were performed in 2004, 2014, 2016.  These surveys documented 13 – 21 plant species with the greatest number occurring in the latter years. Unfortunately, Bashan Lake had extensive areas of variable-leaf watermilfoil (Myriophyllum heterophyllum) and a small area of invasive fanwort (Cabomba caroliniana).

In 2014, the lake’s dam underwent a complete rebuild. In the process, the water was lowered approximately 18 feet. Rebuilding was completed in early 2015. When the lake was lowered, most of the variable-leaf watermilfoil that escaped CAES IAPP treatment was thought to have been killed by exposure to freezing and desiccation; however, in 2017 considerable areas of the plant reappeared. These areas were treated in the fall of 2017 with the herbicide Navigate. Unlike previous years where Navigate treatments were effective, the 2017 application offered little control. Resistance to Navigate was surmised. Fortunately, a new herbicide called ProcellaCOR became available and CAES IAPP tested in the fall of 2018.Successful control was obtained of the variable-leaf watermilfoil in all treatment areas of Bashan Lake except in the boat launch cove. Better control was considered likely if an early summer treatment had been employed.

In June 2020, five acres of variable watermilfoil were treated with ProcellaCOR. Our late summer 2020 survey found no variable-leaf watermilfoil anywhere in the lake. Because none were found, there is a likelihood that the herbicide moved into other parts of the lake with efficacy. Fortunately, ProcellaCOR is selective to certain broadleaf plants and not harmful to most grassy plants. Among these are the common and state listed pondweeds (Potamogeton species). Our post-treatment plant survey showed 25 species inhabited the lake which is greater than any of our previous survey years. State listed Vasey’s pondweed (Potamogeton vaseyi) remained robust near transect 14. Fanwort was found in a small patch just north of the cove with the state boat launch by transect 3 and most was covered with a benthic barrier. Native species including arrowhead (Sagittaria species), waterwort (Elatine species), spikerush (Eleocharis species), and sevenangle pipewort (Eriocaulon aquaticum) were found with the greatest diversity and abundance in the coves and along the southern shoreline. Deeper water supported abundant purple bladderwort (Utricularia purpurea) and charaphyte.

Species recorded in our 2020 survey of Bashan Lake.
Scientific Names
*Invasive Species
Arrowhead Fanwort* Purple bladderwort Watershield
Bur-Reed Floating bladderwort Ribbon-Leaf pondweed Waterwort
Cattail Golden hedge-hyssop Sevenangle pipewort Western waterweed
Common bladderwort Humped bladderwort Small pondweed White water lily
Common duckweed Leafy pondweed Snailseed pondweed Vasey's pondweed
Common reed Mudmat Spikerush
Coontail Pondweed Thread-Leaf naiad

Other Bashan Lake Surveys: 2016, 2014, 2004