Wayne Presents! Androscoggin Lake Algal Bloom Forum
Questions and Answers:
On November 10th, 2025 we participated in the Wayne Presents! Androscoggin Lake Algal Bloom forum. Our Executive Director, Lidie Robbins, shared updates on our ongoing efforts to understand the blooms and the data and analysis needed to identify management solutions. Other speakers included Ted Tucci, ALIC’s President, sharing ways the community can get involved and ALIC’s 2026 action plan, and Matt Scott, retired DEP lake expert, discussing other lakes that have struggled with algal blooms.
Approximately 150 attended the event (in-person and online). The program was followed by a comments/question-and-answer period. We have shared answers to these questions below, along with those asked online, and will update them periodically. You can view the recorded presentation here.
Sources of Phosphorus
Septic Systems
Is the community adequately informed about how aging or heavily used septic systems affect lake health?
Many people do not understand how to properly maintain a septic system to prevent harming water quality. Learn more about the importance of knowing your septic system on our Septic System Vulnerability Study page, including taking our quiz to better understand what next steps you can take.
What happens to septic systems during flooding and how does this affect the lake?
When a septic system is flooded, it cannot function properly, causing. nutrients to escape the system, potentially harming water quality. You can read important information from the EPA here for what to do after a septic system floods.
Replacing septic systems can be very expensive—are financial resources or assistance programs available?
The Small Community Grant program provides funding to municipalities to fix documented septic system failures. Our Septic System Vulnerability Study is a tool to help determine those locations most at risk and which are a priority to be fixed.
Are current septic system standards in need of revision to better protect the lake?
The State’s leading septic system expert, retired soil scientist David Rocque, says yes. Even systems installed according to current standards may not filter out nutrients (such as phosphorus) due to being installed in sand, gravel, or fractured bedrock. This is called “short-circuiting”. A law passed this year directs the State to revise the design standards for septic systems to prevent short-circuiting.
Dead River
What is the impact of fluctuating water levels on lake health, erosion, and water temperature, and how much control does the dam provide?
Androscoggin Lake’s connection to the Dead and Androscoggin Rivers creates a unique situation for remediating the lake’s water quality. During spring snowmelt, river flows increase and the Dead River flows into the lake. These flows can cause sediment erosion and transport, septic system flooding, debris accumulation, and other factors that can negatively impact water quality. We’re continuing to work on understanding the frequency and impact of these “backflow” events.
Unlike most dams, which are constructed to impound and regulate water within the lake, the Dead River “dam” was not designed for that purpose. When installed in the 1930s, it was designated a “pollution control device,” intended to reduce the amount of historically polluted river water entering the lake. Flap gates on the dam normally allow water to flow out of the lake, but not back into the lake. During very high water events, water can flow over the top of the dam and into the lake.
Lake Sediments
What effect do powerboats have in stirring up contaminated sediments, and could limiting horsepower help protect lake health?
While we don’t know the extent of the impact on Androscoggin Lake, studies have shown that motor boats can stir up sediments from the lake bottom. This could have the potential to bring additional phosphorus into the water column, impacting algae growth. Part of our studies are to understand just how much of the lake’s bottom could be releasing phosphorus throughout the season.
Other Sources
How do household lawn-care and pest-control practices affect lake water quality?
Fertilizers, herbicides, and pesticides can contribute phosphorus and chemical pollution to lakes. It is recommended to reduce or stop their use to protect water quality. And, NO fertilizer use is allowed within 25’ of the lake.
Could Androscoggin’s position at the end of the 30 Mile River watershed be contributing to higher nutrient inflow from upstream sources?
The location of Androscoggin Lake within the watershed means that there is potential for nutrient loading from lakes upstream. Understanding how much impact the upstream waters have is an important part of the complex issue.
Potential Solutions and Management
Will the upcoming study include an analysis of the dam? (Should it be maintained or. removed, does it prevent fish passage, what are the impacts of backflushing; what is its structural condition)?
Yes, we are consulting with engineers to better understand all of the issues related to the Dead River Pollution Control Device, aka the dam.
Is alum treatment a possible solution for Androscoggin Lake?
Our ongoing data collection efforts will provide the information needed to weigh all potential solutions, including an alum treatment. Until we have more data, we cannot know if alum is a viable option.
What are the needs of the advisory committee?
An advisory committee of stakeholders will be created to help guide the many aspects that addressing this issue will entail. The committee will include representatives of the towns, businesses, property owners, and other lake users. Additional work groups will be created to focus on issue areas.
Water Quality Data
Were any tributaries identified as having higher phosphorus levels than the lake itself?
Results from our tributary sampling from 2022 to 2024 varied. Phosphorus concentrations from these samples had a much wider range than in-lake concentrations. Understanding weather and flow during the time of tributary sampling is a priority next study step. We’ll be needing volunteers to help with this next effort – reach out to us if you’d like to assist!
What are the current phosphorus levels in the lake, and what concentrations increase the risk of algal blooms?
Water Quality data can be found on our Androscoggin Lake page, with recent “Phosphorus Profile Grab Sample” results at the bottom of the page. Generally speaking, in-lake phosphorus concentrations less than 10 ppb are ideal for a healthy lake. Lakes with in-lake phosphorus concentrations of ~13 ppb or more are known to sustain algal blooms, and blooms become frequent as average concentrations approach 20 ppb. This year, Androscoggin averaged ~15 ppb, with the highest in-lake concentration being 21 ppb.
How much are warmer temperatures contributing to the worsening water-quality trends?
A likely effect of a warming climate is an increase in algae abundance in lakes. Warmer lake water generally enhances the conditions for algal growth and extends the annual growing season. Additionally, the increase in the intensity and frequency of storms is also a threat to water quality, as they lead to higher levels of polluted runoff.
How extensive are the toxins produced by harmful algal blooms, and can they become airborne and travel long distances?
Detectable toxins were found in the lake this season from samples taken by staff from both 30 Mile and Maine DEP. Higher concentrations of toxins were detected in the scum accumulation along the shore, which is typical. It is important to understand that the algal scum is what typically produces the most toxins and, therefore, should be avoided.
Studies have shown that algal toxins can become airborne when waves break. The tiny aerosol particles produced could be inhaled by people, exposing them to toxins even if they avoid the water itself. There are still many unknowns about these aerosols and their effects on human health at this time.
Can algal blooms persist into winter?
It’s possible for some blooms to persist late into the season and there have been cases of winter blooms under the ice.
Why has lake health continued to decline since 2020 despite increased mitigation efforts?
Lakes are very sensitive ecosystems and even small changes in phosphorus can have a big impact. Phosphorus is the nutrient that most influences the growth of algae in lakes. Its natural occurrence in lake water is very small, but there are many sources of phosphorus that sustain algal blooms over time.
One source is from erosion. Rain events cause a lot of water to move over the landscape, transporting eroded material with it into our lakes and ponds. With increased development, there are fewer opportunities for rainwater to be slowed down, allowing nutrients to be filtered out, on its way into the lake. We have ramped up projects and programs on Androscoggin Lake focused on reducing sources of phosphorus polluting the lake, such as LakeSmart initiatives and grant-supported projects, that reduce harmful runoff.
Another source of phosphorus is the lake sediment. This phosphorus has accumulated over many years. During the summer, low oxygen levels at the bottom of the lake can cause a chemical reaction to occur at the sediment surface. This reaction causes the sediment to release phosphorus into the water column, a process known as “internal phosphorus loading.”
All of the contributing sources add up. This is why we are continuing work to limit what enters from the land while we develop our understanding of the impact of each of these sources. Regardless of the final management solutions, limiting new phosphorus from entering the lake is always beneficial.
Understanding the significance of each source of phosphorus in the lake will help us identify the most effective and cost-efficient long-term solutions. We cannot implement any major management practices without better certainty that they will be cost-effective, which is why it is essential to complete our data collection and analysis first.
Why is Pocasset Lake clear while Androscoggin Lake is experiencing algal blooms?
Each lake is unique. Factors such as depth, size, geology, and hydrology vary from lake to lake and all have an impact. It is difficult to directly compare one lake to another.
Shoreland Zoning
Are existing ordinances, such as shoreland zoning, being properly enforced?
The health of Maine’s lakes and ponds depends on the collective effort and goodwill of all who live within their watersheds. Laws and ordinances were created and are enforced by the State and local municipalities to further protect the fragile environment that surrounds our lakes.
Maine’s Shoreland Zoning Law requires municipalities to adopt, administer, and enforce local ordinances that regulate land use activities (construction, vegetation clearing and soil disturbance) in the shoreland zone – the area within 250’ of lakes, ponds, and wetlands, and within 75’ of streams.
This law is one of the best protections we have for our lakes, and one of the reasons that Maine’s lakes are much healthier than lakes in other parts of the country. Because it places a lot of responsibility for enforcement on small towns, it’s vital that the local Code Enforcement Officers (CEOs) have the resources and support to do their jobs.
Violations do occur, and sometimes they go unnoticed. Sometimes property owners unknowingly violate ordinances. Help educate your neighbors, especially when new people move into town. When you see a violation, report it to your CEO.
Read more about the importance of shoreland zoning protections in our Living on the Lake info sheet or in our newsletter article here.
How can residents contact their local code enforcement officers?
Wayne: Chip Stephens, Phone: (207) 685-4983, Email: ceolpi@waynemaine.org
Leeds: Larry Grant, Phone: (207) 524-5171, Email: ceo@townofleeds.com
Other Questions
Is there a reliable way to determine changing water levels and the high-water mark?
There is a USGS (United States Geological Survey) marker at the Yacht Club that is utilized as a measurement tool for the high water mark and for flood levels due to the unique fluctuations observed on the lake.
Can you identify where on the lake certain submitted photographs were taken?
There were many images used in the presentation. A few images were taken from the air (by drone or by plane), some by shorefront owners’ properties, and some by 30 Mile staff along the eastern shoreline. Scum accumulation can depend on the direction of the wind, which pushes algae towards the shore, causing a buildup. This can make some areas look clearer than others despite the entire lake being affected by the bloom.
Can towns increase educational outreach for property owners and renters, such as information on LakeSmart practices and septic maintenance?
There are many educational resources about septic system maintenance and use:
– Septic System Vulnerability Study | 30 Mile River Watershed Association
– Maine Lakes – Septic Systems
– SepticSmart Education Materials | US EPA
Maine Lakes has an abundance of resources related to lake-friendly practices available here. They also lead the state-wide program, LakeSmart. Participating in educational programs like LakeSmart can help you make your property safer for the lake. If you’re interested in scheduling a LakeSmart visit from the ALIC volunteer team, you can contact them here.