Overview

• 2020: Harmful algae bloom and a 19-day lake closure.

• 2021-2022: Analysis of Alewife Brook flow and maintenance by CLWA, Essex, and the Commonwealth.

• 2023-2024: Preliminary assessment of lake water quality funded by CLWA donors.

• 2025-2026 plan: Two years of data collection and analysis to support lake-management and watershed-restoration planning, with Beck Pond added to the study. Funding was described as coming from Essex, Hamilton, the Commonwealth, and CLWA donors.

Low dissolved-oxygen levels near the bottom of the lake can create areas with little aquatic life, contribute to phosphorus release from sediment, and support conditions associated with cyanobacteria blooms.

CLWA positioned a science buoy over the lake's deepest area, approximately 23 feet, so a sensor could record dissolved-oxygen levels hourly. Lake users were asked to respect the installation and avoid activity that could disrupt data collection.

Between June 18 and June 22, 2025, CLWA received reports of small suspected cyanobacteria blooms near the boat ramp, Red Gate Road, and Echo Cove.

Lake consultant Hillary Kenyon advised that visual identification and prompt reporting are important because bloom density can vary widely across a lake. CLWA began coordinating public awareness and response with the Boards of Health and town officials in Essex and Hamilton.

Community members were encouraged to avoid visible blooms, learn basic visual-identification methods, and report suspected blooms with a location and photograph. For general background, identification guidance, and health-related resources, see Algae Blooms.

Current lake conditions and public-health guidance should always be confirmed through the latest CLWA and municipal notices.