Cyanobacteria outbreak observed on Damariscotta Lake

Tue, 06/07/2022 - 1:30pm

While performing routine water quality monitoring on June 2, Midcoast Conservancy’s Damariscotta Lake Watershed Manager, Patricia Nease, observed what appeared to be cyanobacteria aggregates near the Bunker Hill Boat Launch. Upon further investigation in the following days and in collaboration with scientists from the Bigelow Laboratory for Ocean Sciences, cyanobacteria aggregates were documented throughout the entire lake - the South Arm, Muscongus Bay, and Great Bay.

While naturally occurring, excess quantities of cyanobacteria can present human health risks to humans and pets. Thankfully, the concentration does NOT appear to meet "bloom" criteria at this time, yet this is still a concerning water quality issue.

“We have recorded cyanobacteria outbreaks on the lake for the past few summers, but they have generally occurred late in summer and have been limited to the South Arm. What is particularly concerning this year is that this outbreak is so early and widespread, indicating a lake that may be increasingly distressed from warming waters and excess nutrient pollution,” explained Nease.

Midcoast Conservancy will continue to monitor this and future cyanobacteria outbreaks on Damariscotta Lake. Nease also added “There are inherent risks in open water swimming. We always recommend best practices, including to avoid scummy or dense areas, avoid inadvertently swallowing lake water while swimming, keep pets from drinking the lake water, and avoid using lake water for drinking or household use.”

For the latest updates on cyanobacteria and other Damariscotta Lake water quality issues, please follow Damariscotta Lake Watch on Facebook and Instagram.

More info on cyanobacteria, what causes it, and what can be done about it can be found here: