Androscoggin Lake: Algal Bloom Response

Androscoggin Lake experienced a severe cyanobacteria bloom in the summer of 2021 and 2023. Near-bloom conditions were documented in 2022. Maine Department of Environmental Protection (Maine DEP) defines a “lake-wide algal bloom” when water clarity <2 meters (~6 feet) depth at the deepest point in the lake (monitoring station #1). 

• The blooms in Androscoggin Lake have consisted of cyanobacteria (formerly called blue-green algae)
• Cyanobacteria bloom when there’s too much phosphorus in the lake.
• Some species of cyanobacteria can produce toxins under certain conditions
• Not all cyanobacteria blooms are toxic
• Areas where the algae have concentrated, forming dense scums or accumulations, should be avoided by humans, pets, and livestock
• Avoid swallowing lake water while swimming, and do not allow pets or livestock to drink lake water
• Avoid using lake water for household uses, cooking, or drinking
• Shower and wash swimsuits after swimming

Cyanobacteria rely on three things: light, temperature, and nutrients. When it rains, phosphorus enters the lake via stormwater runoff that is delivered from the land in the watershed surrounding the lake. Phosphorus is a naturally occurring nutrient found in soil, fertilizers, pet and livestock waste, and septic systems among other sources. It is found in very small amounts in the lake water, but is found in very large amounts on land in the watershed surrounding the lake. Every time it rains, water flows over the land and flows downhill – into the ditches, streams, and Androscoggin Lake. When too much phosphorus enters the lake, excess algae growth occurs.

Another important source of phosphorus is the sediments at the lake bottom. In the summer months, low oxygen levels in the deep waters of the lake can cause a chemical reaction to occur in the sediment. This reaction causes the sediment to release phosphorus into the water — a phenomenon known as “internal phosphorus loading”. To learn more, please read Androscoggin Lake’s 2023 Water Quality Report here: https://30mileriver.org/androscoggin-lake/. 

For more information about algae blooms and cyanobacteria, please visit Maine DEP’s informational webpages via the following links:

• https://www.maine.gov/dep/water/lakes/algalbloom.html
• https://www.maine.gov/dep/water/lakes/cyanobacteria.html

We do know that the species causing this bloom has the ability to produce toxin. We are collecting water samples for toxin analysis by US EPA, however test results are not immediate. 

Maine DEP has been testing for cyanotoxins in Maine lakes for decades. Of all the toxin samples Maine DEP has collected, there were only a few open-water samples that exceeded EPA’s Drinking Water standard for the algal toxin microcystin for infants and non-school-age children. None of the samples exceeded the standard for school-age children or adults.  No open water samples have exceeded EPA’s Recreational Standard – even when collected from lakes with blooms that are chronic and severe. 

However, Maine DEP has detected very high concentrations of the algal toxin microcystin in down-wind algal scums that can accumulate along shorelines.  This is why we advise everyone to stay away from any concentrated scums or accumulations near shorelines or in down-wind coves. Do not inadvertently drink the water in these areas, and do not let small children, pets, or livestock play in these areas or drink from the lake. Shower after swimming, and do not use lake water for household uses like cooking or drinking. 

Out of an abundance of caution: When in Doubt -Stay Out!

• Participate in erosion control projects. If you are a landowner with an erosion site identified during the 2022 watershed survey, contact 30 Mile to see what cost-sharing opportunities are available to help implement your project! 
• Become LakeSmart! Contact ALIC’s LakeSmart team to receive a FREE evaluation, and learn more about how you can improve your property for the benefit of Androscoggin Lake. Request an evaluation by emailing lakesmart@androscogginlake.org, and visit  https://www.lakes.me/lakesmart to learn more about this fantastic program!
• Become a member of the Androscoggin Lake Improvement Corporation (ALIC) and support their work to improve and protect Androscoggin Lake: https://www.androscogginlake.org/join.htm 
• Donate to 30 Mile to support our water quality monitoring program and our work to address this problem: https://30mileriver.org/ways-to-give/
• Reduce soil erosion on your property as much as possible- exposed soil delivers phosphorus to the lake each time it rains – Phosphorus feeds algae in the lake!
• Establish or improve the stand of vegetation on your shoreline. The bigger (wider) your shoreline buffer, the better it is for Androscoggin Lake.
• Stop using fertilizers on your lakefront properties
• Maintain a healthy septic system, and pump your septic tank regularly.
• Learn more by visiting Maine DEP’s website for Shorefront Property Owners: https://www.maine.gov/dep/land/watershed/camp/index.html

30 Mile continues to monitor Androscoggin Lake into October to document improved conditions in the lake. Over the winter months, we will analyze the data and compile our findings into an annual water quality monitoring report, which will be available via our website once complete. 

In the meantime, be sure to check out the Secchi disk and dissolved oxygen data collected throughout this year’s monitoring season by visiting 30 Mile’s water quality webpage for Androscoggin Lake: https://30mileriver.org/androscoggin-lake/.