HLLT Report to Falmouth Town Council
2025

Table of Contents

Introduction

The Highland Lake Leadership Team (HLLT) is a formal partnership among the Town of Falmouth, the Town of Windham, and the Highland Lake Association (HLA), working collaboratively to protect and improve the water quality of Highland Lake. Additional support is provided by the Cumberland County Soil & Water Conservation District (CCSWCD), the Maine Department of Environmental Protection (DEP), residents, road associations, and other watershed stakeholders.

For more than 30 years, these partners have worked to reverse declining water quality trends. Those efforts resulted in Highland Lake being removed from the State’s impaired waters list and returning to compliance with its designated classification standards. However, renewed signs of water quality decline and bacterial blooms led to the formal establishment of the HLLT in 2018 to oversee coordinated, long-term protection efforts.

The HLLT directs implementation of the 2020–2030 Highland Lake Watershed Management Plan, an EPA- and DEP-approved plan endorsed by the Towns of Falmouth and Windham and the Highland Lake Association. The Plan prioritizes actions aimed at reducing phosphorus loading—the primary driver of algal growth and water quality degradation.

HLLT Charge and Responsibilities

The HLLT is tasked with:

1.  Overseeing and assisting with implementation of the 2020–2030 Watershed Management Plan.

2.  Establishing committees focused on Plan implementation, including:

   • Water Quality

   • On-the-Ground Projects

   • Ordinance Review

   • Education and Outreach

3.  Coordinating scientific monitoring and research efforts

4.  Seeking expert input as needed

5.  Amending the Plan when warranted by new information or changing conditions

6.  Providing regular updates to watershed residents and the broader community

Observations  for 2025

1. Rainfall and Lake Levels

Southern Maine experienced a relatively normal spring, followed by a severe drought beginning in July and lasting through the fall. Reduced rainfall likely limited phosphorus-rich runoff entering the lake during late summer.

Beaver Dam

A significant development in 2025 was the construction of a beaver dam along the lake’s outlet stream between Highland Lake and the concrete dam in Westbrook

Beaver Dam Impacts:

Alewife migration...
...plays an important ecological role in phosphorus balance. Approximately 30% of adult alewives die after spawning, contributing significant phosphorus to the lake.
Juveniles typically absorb phosphorus during growth and export it to the ocean when they migrate.
In 2025, many juveniles were unable to leave due to the beaver dam and fishway closure. Observations of bass feeding heavily on trapped juvenile alewives indicate that phosphorus remained in the lake rather than being exported.

2. Water Clarity and Quality

Secchi disk measurements in 2025 followed typical seasonal trends until August, after which clarity improved during the late summer “clear water phase.” Reduced rainfall likely contributed to decreased nutrient runoff. 
Long-term monitoring (charts below) shows: 

• A gradual decline in phosphorus concentrations.

• Corresponding improvement in Secchi disk transparency. 

• Continued reversal of prior declining water quality trends.

Few lakes achieve measurable phosphorus reductions without costly alum treatments.

 Highland Lake’s improvements, without alum treatments, reflect sustained watershed management, municipal ordinances, erosion control projects, lake environmental education, and strong community engagement.

3. Education and Outreach

The Education and Outreach Committee continued its year-round engagement through:

• Distribution of Best Management Practices (BMP) materials.

• Social media campaigns and informational videos.

• Updates to the HLA Guide to Lake-Friendly Living, now adopted by at least four other lakes.

In Spring 2025, a watershed road walk was conducted with a Town of Windham engineer. Representatives from road associations, contractors, and CCSWCD attended. Topics included:

• Culvert sizing and maintenance

• Water diversion berms

• Mono-sloped vs. crowned road design

• Settling basin cleaning

• Erosion prevention strategies

The event was well received and will be repeated in 2026.

4. Grant Activity

Windham Watershed Protection Grants

The Town of Windham reinvests boat registration fees into watershed protection grants (approximately $38,000 annually). In 2025:

• Four projects were funded.

• One Highland Lake project ($8,945) addressed erosion in the Beach and Orchard Road area.

• Work included culvert installation and drainage improvements and appears highly successful.

DEP 319 Clean Water Act Grant

In partnership with the Cumberland County Soil & Water Conservation District, the Highland Lake Association secured a Section 319 grant to address road runoff entering Highland Lake beginning in 2025. This project will further reduce nonpoint source phosphorus loading.

Ecological Observations – 2025

Ice-In / Ice-Out

• Ice-In: December 9, 2025 (earlier than average)

• December 21: High winds and a warm spell temporarily opened part of the north basin.

• Ice thickness exceeded one foot, supporting ice fishing, snowmobiling, skating, and kite skating.

• HLA volunteers continued winter water quality sampling under ice cover.

Ice-out for the 2026 season had not yet occurred at the time of this report.
(Editor Note: Ice-Out for 2026 was Thursday April 2)

Conclusions

The year 2025 presented both challenges and progress for Highland Lake:

• Severe drought reduced runoff inputs but altered outlet dynamics.

• A beaver dam protected lake levels yet disrupted alewife migration and downstream flow.

• Long-term phosphorus reductions and improving water clarity trends continued.

• Education, outreach, and road association engagement strengthened watershed stewardship.

• Targeted grant-funded projects addressed erosion and runoff sources.

• Wildlife outcomes were mixed, with no loon chicks but successful eagle nesting.

The collaborative model embodied by the Highland Lake Leadership Team continues to demonstrate measurable success in protecting Highland Lake’s water quality. Sustained vigilance, adaptive management, and community engagement remain essential as climate variability and watershed pressures evolve.

Goals for 2026

Ordinance Committee - HLLT is discussing and will likely be advocating for two potential modifications to the Falmouth ordinance to match the protective measures established by Windham, ensuring uniform safeguards for the lake.

1. Review trigger for Surface Water Permit: Proposal to revising the threshold for when a surface water permit is required due to ground disturbance. This change would ensure that all activities with potential for significant runoff and sedimentation are more consistent across the entire shoreland zone.

2. Sizing of Best Management Practices (BMPs): The current ordinance doesn’t provide a basis for sizing BMPs according to rainfall volumes, which complicates the implementation of effective stormwater control.  These concepts are being discussed with Code Enforcement and appropriate town processes will be followed for any HLLT recommended changes.

Education and Outreach: Continued engagement with road association leadership through another road walk fostering direct dialogue and expanding member involvement. Additionally, several BMP videos have been created that will be distributed through newsletter and social media campaigns.

Watershed Management: Execute projects funded by Windham and the DEP 319 Grant. Key actions include finalizing the work plan, securing matching funds, and signing contracts to start work on time. The Highland Lake Leadership Team's Watershed Management Committee will help assist with and oversee progress of the $97,000 grant project goals.  

Water Quality Committee - Continue monitoring and tracking water quality statistics to ensure the health of Highland Lake.