Photo overlooking West Lake in Guilford, CT from August 2021.

West Lake, Guilford - 2021

2021 aquatic plant survey map of West Lake in Guilford, CT.

2021 Aquatic Plant Survey of West Lake

Transect Data | Water Data

West Lake is a 52-acre lake located in Guilford, CT. The lake was surveyed for the third time in 2021 by CAES IAPP with the previous surveys occurring in 2005 and 2010. Nineteen native species were found in 2021, compared to 27 in 2010 and 18 in 2005. Minor naiad (Najas minor) was the only non-native invasive aquatic plant found during the 2005 and 2010 surveys; however, it was not observed during our 2021 survey. No invasive aquatic plants were therefore observed in 2021. This along with the decline in native species was likely caused by an aquatic herbicide application performed approximately a month prior to our survey. Two invasive non-aquatic wetland plants were found during the 2021 survey: phragmites (Phragmites australis) and purple loosestrife (Lythrum salicaria). Our documentation of non-aquatic plant species is outside the scope of CAES IAPP surveys and is performed at the discretion of the surveyor. Comparing their presence from survey-to-survey is therefore unreliable. 
               The shoreline was densely populated with swamp loosestrife (Decodon verticillatus) on the western and northern sides of the lake. Lily pads such as white water lily (Nymphaea odorata), yellow water lily (Nuphar variegata), and watershield (Brasenia schreberi) were also common. The southern part of the lake was more densely vegetated with stands of Robbins’ pondweed (Potamogeton robbinsii), large-leaf pondweed (Potamogeton amplifolius), and southern naiad (Najas guadalupensis). There was a large amount of decaying plant matter because of the treatment and the deeper areas of the lake had charaphyte which is a plant-like freshwater algae. Water transparency was 1.8 meters (6 ft.) which is below average for Connecticut lakes. A combination of a modest algal bloom and tea color from organic derivates appeared to be the cause. This was likely accentuated by the herbicide treatment.

Species recorded in our 2021 survey of West Lake
Scientific Names
*Invasive Species
Arrowhead Lesser bladderwort Purple loosestrife* Water smartweed
Berchtold's pondweed Little floating heart Robbins' pondweed Watershield
Cattail Phragmites* Southern naiad White water lily
Common bladderwort Pickerelweed Spikerush Yellow water lily
Humped bladderwort Primrose-willow Spineless hornwort
Large-leaf pondweed Purple bladderwort Swamp loosestrife

Other West Lake Surveys: 2010, 2005