Overview: Lake Massapoag's Memorial Beach and other swimming beaches had good water quality in 2023, with the exception of Community Center Beach. This Dashboard summarizes the progress we are making in identifying hot spots for E. coli and phosphorus, which will help inform future recommendations for source reduction, plans for mitigation, and infrastructure projects to improve lake health.
Phosphorus and E. coli testing at lake inlets Because cyanobacteria blooms are often fed by excess phosphorus, in 2022 LMAC added monthly testing of phosphorus levels at inflow sites. The results can be found here. Samples were collected by town staff and volunteers, and phosphorus analysis performed by a professional lab. Some water samples were collected during and after rainstorms, to capture the impact of runoff. Several of the inflows showed high levels of phosphorus during the summer, especially during or after rain a significant rainstorm.
Neponset River Watershed Association (NepRWA) testing of Sucker Brook New for 2022, NepRWA added a Lake Massapoag site, Sucker Brook which is the main inflow into the lake, to its Community Water Monitoring Network (CWMN). Volunteers collected monthly water samples May-October for analysis of E. coli, total phosphorus, dissolved oxygen, pH, chlorophyll-a, and water temperature. NepRWA also did a hot spot analysis of Sucker Brook, testing for phosphorus and potential sources of pollution, as this brook enters the lake near the Community Center Beach, which has been the most problematic site for high E. coli. For data on all of NepRWA's CWMN sites, click on the interactive map. Comprehensive Professional Lake Water Quality Testing We used a professional environmental services firm to obtain a snapshot of multiple lake water quality parameters in the deep hole of the lake, monitoring the water column from the surface to the lake bottom, during the late spring, mid-summer, and early fall. Similar testing was done in the south and west coves. The Lake’s Deep Hole, Fletcher’s Cove, and South Cove showed high phosphorus levels in early June. Results are available on the town website.
Cyanobacteria Testing LMAC, in consultation with EPA biologist Hilary Snook, began weekly testing of the deep hole for cyanobacteria. See detailed Cyanobacteria Test Results. Microscopy was used to identify specific genuses of cyanobacteria, which is important because different genuses produce different toxins. A fluorometer was used to measure the levels of phycocyanin, a protein produced by cyanobacteria, as an indicator of the levels of cyanobacteria present. Levels of cyanobacteria in the deep hole were low all summer, and only one bloom was reported on Sept. 9, and it cleared quickly. Learn more about cyanobacteria.
Historical Data A comprehensive Diagnostic/Feasibility Study: Lake Massapoag in 1984 provides helpful background, historical data on lake water quality, and options and recommendations for implementation. Without action, the lake was predicted to be eutrophic (dead) by the year 2000. Many actions were taken, gaining many years of lake health. Today, excess nutrients, stronger storms, runoff, etc. threaten the lake.
Future LMAC received two state grants in 2023 to develop a Climate Resilient Watershed-Based Plan for Lake Massapoag 2024-2025. We thank the Executive Office of Energy and Environmental Affairs for its Municipal Vulnerability Preparedness (MVP) Action grant, and the Department of Environmental Protection for its 604(b) Watershed Management Planning grant. The Plan will analyze nutrient inflows and the nutrient budget for the lake; watershed inflow, storm drain, shoreline seepage, surface runoff, and sediment deposition to determine where excess nutrients can best be controlled. Sustained effort and investments to safeguard lake water quality, limit excess nutrients, harmful bacteria, and invasive weeds will be needed for several years, as more intense weather associated with climate change increase the impact of excess nutrients, rain, runoff and heat.