Androscoggin Lake Bloom Information

Latest Updates


1. The Androscoggin Lake 2021 Water Quality Report is now available!

Click here to view the report.

2. Androscoggin Lake Watershed Survey Dates Announced!

On May 12 & 13, 2022 the Androscoggin Lake Improvement Corporation (ALIC) and 30 Mile, with the support of the Towns of Wayne and Leeds, will be conducting a watershed survey of the Androscoggin Lake watershed. The purpose of the survey is to identify and prioritize sources of soil erosion and stormwater runoff that can bring phosphorus into the lake from developed areas throughout the watershed. Watershed landowners will receive more information about this survey in the coming months.

Attend a FREE training seminar and learn about watersheds, how to identify erosion and other sources of polluted stormwater runoff, and ways to help improve water quality in Androscoggin Lake. If you are interested in being a survey volunteer, learn more and sign up here.

For more information, visit 30 Mile’s watershed survey page.

30 Mile will update this webpage as information becomes available-
please check back for more updates!


A bloom of cyanobacteria (formerly known as blue-green algae) was observed this year in Androscoggin Lake starting in August 2021. Localized blooms were first observed in areas near shorelines and in coves. In late September, water clarity had officially reached lake-wide blooms status (clarity <2 meters depth at the deepest point in the lake) as defined by the Maine Department of Environmental Protection, and persisted through October.

What you need to know:

  • The bloom in 2021 was caused by cyanobacteria
  • 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

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


    What are cyanobacteria?

    Cyanobacteria are a type of algae. Formerly called blue-green algae, cyanobacteria are aquatic bacteria that are able to photosynthesize. Originally called blue-green algae because dense blooms will turn the water green, or blue-green in color, cyanobacteria are a natural and important part of the lake ecosystem, and can be found in all lakes all over the world. However, when nutrient (phosphorus) concentrations are high enough and conditions are just right, their population can explode. The result is what we call a “cyanobacteria bloom” or “algal bloom.”

    What kind of cyanobacteria is it?

    The species of cyanobacteria causing the bloom in 2021 has been identified as Dolichospermum (formerly known as Anabaena), a common bloom-forming species in Maine lakes. Microscope photos (right, courtesy of R. Windecker) show the filamentous algae consisting of multiple bead-like cells of three distinct cell types. Dolichospermum can produce toxins under certain environmental conditions.

    Is the water toxic?

    We do know that the species causing this bloom has the ability to produce toxins, but we do not have toxin results yet.

    Of all the toxin samples Maine DEP has collected from Maine lakes over the past decade, 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 are advising 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!

    What caused the bloom?

    Cyanobacteria rely on three things: light, temperature, and nutrients. It is likely that the high air and water temperatures this summer, in addition to the ongoing input of nutrients (phosphorus) as a result of stormwater runoff during summer rain storms, created the perfect environment for an algal bloom. 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 element 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. Image credit: UW Extension and Wisconsin DNR

    What can be done to stop it?

    Our current understanding is that the bloom was caused by phosphorus loading from the surrounding watershed. The watershed areas of most concern are the direct watershed surrounding the lake and the Dead River, which this summer may have flowed into the lake instead of into the Androscoggin River due to several unusual factors. 

    The solution: reduce the amount of phosphorus entering the lake via polluted stormwater runoff.

    To prevent another algal bloom, we must greatly reduce the phosphorus flowing into the lake. Septic systems must be functioning properly and pumped regularly. Polluted stormwater runoff needs to be prevented from entering the lake, by every landowner doing their part to be sure that soil, fertilizers, and waste are not washing or leaching into the lake from their property – from roads, driveways, paths, lawns, and more. We need to keep as many trees and shrubs, and as little lawn, growing around the lake as possible. 

    A more in-depth study of the lake is needed before any in-lake treatment options could be recommended or permitted.

    What is 30 Mile doing?

    30 Mile has been working closely with ALIC and the Maine DEP to identify next steps. Androscoggin Lake is eligible for state and federal grant funding (EPA Clean Water Act – Section 319) to help fund on-the-ground watershed improvements that reduce the amount of polluted runoff (phosphorus) entering the lake. Before we can apply for funding, a watershed survey must first be completed. 30 Mile, ALIC, and local stakeholders, with technical assistance from Maine DEP, are now planning a watershed survey in Spring 2022.

    The more quickly we can address sources of phosphorus throughout the watershed, the better it will be for water quality in Androscoggin Lake. In addition to watershed improvements, this year’s bloom warrants a more in-depth study of the lake itself and the complex dynamic with the Dead River and its dam. 30 Mile will continue to work with ALIC, watershed towns, and Maine DEP to help guide further study of the lake and it’s watershed.

    What you can do RIGHT NOW to help:

    • 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, and visit 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: 
    • Donate to 30 Mile to support our water quality monitoring program and our work to address this problem:
    • 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:

    Near-Live Water Quality Data & 2021 Monitoring Report

    30 Mile continues to monitor Androscoggin Lake into November 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: