E. coli & Beach Closures
The levels of a bacterium, Escherichia coli (E. coli), which is an indicator of warm-blooded animal fecal contamination, are measured as the primary indicator of Lake Massapoag water quality and its safety for swimming. Here is the link to 2024 swim beach E. coli levels & beach closures (attachment at the bottom, right). A summary of 2023 E. coli test results is available.
The Town of Sharon tests both the Memorial Park Beach and Community Center public swimming areas for E. coli weekly during the swim season. Of the two public beaches, Memorial Park Beach has the best record of water quality, and had no elevated E. coli levels in 2023. High E. coli levels in this area typically clear out by the next day, likely due to the higher rate of water turnover. The Community Center Beach is closed to swimming in 2024 and was closed to swimming in 2023 due to high E. coli levels in 2022, which continued in 2023. There is less water flow in this area, so the high counts tend to persist longer, leading to beach closures until retesting counts fall below the level set by the Massachusetts Department of Public Health. Testing during 2023 also showed frequent high E. coli levels in Sucker Brook, which empties into the lake near Community Center Beach. Ongoing testing is mapping Sucker Brook for potential sites of E. coli entry within Sucker Brook.
For historical trends, see 2022 and 2021 E. coli results, and 5-year trends for swimming areas.
E. Coli testing details
In accordance with state regulations for swimming water safety (MA law 105 CMR 445.030), the town tests Memorial Park Beach and Community Center Beach for E. coli, with results sent the next day to the Sharon Health Department. Samples are collected weekly at the public swimming areas during the season when the beaches are open for swimming. Testing is also done five days immediately preceding the opening of the bathing season, and before reopening a beach after closure due to high E. coli. Lake Massapoag camps and the yacht club are responsible for testing at their beaches.
When sample results exceed the Massachusetts Department of Public Health's (DPH) water quality standards, the Health Department's policy is to close the beach, resample the water, and reopen the beach upon receipt of a sample result less than the standard. The MA DPH water quality standards require that no sample exceed 235 colony forming units (cfu) per 100 milliliters (ml), and that the geometric mean of the most recent five samples shall not exceed 126 cfu /100 ml. See the Board of Health webpage for detailed information and FAQs on lake closings, retesting, and reopening for E. coli.
Note: The lake may also be closed due to a cyanobacteria bloom, as occurred in July 2021. The suspected cyanobacteria bloom was based on visual inspection, and was necessary because some cyanobacteria produce toxins that are extremely potent and can be lethal, especially to dogs. State law requires a lakewide closure when a significant cyanobacteria bloom is reported until two weekly tests are below the level of concern. Learn more about cyanobacteria and Cyanobacteria testing, which LMAC added in 2022 and 2023.
The Town of Sharon tests both the Memorial Park Beach and Community Center public swimming areas for E. coli weekly during the swim season. Of the two public beaches, Memorial Park Beach has the best record of water quality, and had no elevated E. coli levels in 2023. High E. coli levels in this area typically clear out by the next day, likely due to the higher rate of water turnover. The Community Center Beach is closed to swimming in 2024 and was closed to swimming in 2023 due to high E. coli levels in 2022, which continued in 2023. There is less water flow in this area, so the high counts tend to persist longer, leading to beach closures until retesting counts fall below the level set by the Massachusetts Department of Public Health. Testing during 2023 also showed frequent high E. coli levels in Sucker Brook, which empties into the lake near Community Center Beach. Ongoing testing is mapping Sucker Brook for potential sites of E. coli entry within Sucker Brook.
For historical trends, see 2022 and 2021 E. coli results, and 5-year trends for swimming areas.
E. Coli testing details
In accordance with state regulations for swimming water safety (MA law 105 CMR 445.030), the town tests Memorial Park Beach and Community Center Beach for E. coli, with results sent the next day to the Sharon Health Department. Samples are collected weekly at the public swimming areas during the season when the beaches are open for swimming. Testing is also done five days immediately preceding the opening of the bathing season, and before reopening a beach after closure due to high E. coli. Lake Massapoag camps and the yacht club are responsible for testing at their beaches.
When sample results exceed the Massachusetts Department of Public Health's (DPH) water quality standards, the Health Department's policy is to close the beach, resample the water, and reopen the beach upon receipt of a sample result less than the standard. The MA DPH water quality standards require that no sample exceed 235 colony forming units (cfu) per 100 milliliters (ml), and that the geometric mean of the most recent five samples shall not exceed 126 cfu /100 ml. See the Board of Health webpage for detailed information and FAQs on lake closings, retesting, and reopening for E. coli.
Note: The lake may also be closed due to a cyanobacteria bloom, as occurred in July 2021. The suspected cyanobacteria bloom was based on visual inspection, and was necessary because some cyanobacteria produce toxins that are extremely potent and can be lethal, especially to dogs. State law requires a lakewide closure when a significant cyanobacteria bloom is reported until two weekly tests are below the level of concern. Learn more about cyanobacteria and Cyanobacteria testing, which LMAC added in 2022 and 2023.