More than 40 beaches across Massachusetts were closed to swimming on Wednesday as state health officials warned of elevated bacteria levels and harmful algal blooms affecting water quality.

According to the Massachusetts Department of Public Health, most of the closures were triggered by bacterial contamination, while a small number of beaches were affected by harmful cyanobacteria blooms.

Why Beaches Were Closed

The Massachusetts Department of Public Health monitors recreational water quality through its beach water quality programme. Most of the current advisories were issued after testing detected bacteria above safe swimming limits.

Health officials said bacteria can enter lakes, ponds and coastal waters through stormwater runoff following heavy rainfall, failing septic systems, sewer overflows, agricultural runoff, and waste from wildlife and pets.

Swimming in contaminated water may cause gastrointestinal illness, respiratory symptoms, skin irritation and rashes.

More Than 40 Swimming Areas Affected

According to the Massachusetts Department of Public Health, most closures were triggered by bacterial contamination, which can result from stormwater runoff, sewer overflows, malfunctioning septic systems, wildlife and pet waste, or agricultural runoff. Swimming in contaminated water may cause gastrointestinal illness, skin irritation and respiratory symptoms.

Massachusetts Beaches Closed to Swimming

• Amherst – Puffers Pond @ Mill Street (Bacterial Exceedance)
• Amherst – Puffers Pond @ State Street (Bacterial Exceedance)
• Ashby – Damon Pond Beach (Other)
• Ashland – Hopkinton Reservoir Main Beach (Bacterial Exceedance)
• Barnstable – Keyes Beach at Sea Street (Bacterial Exceedance)
• Beverly – Mingo Beach (Bacterial Exceedance)
• Braintree – Smith Beach (Bacterial Exceedance)
• Brewster – Cliff Pond @ DYS (Harmful Cyanobacteria Bloom)
• Brewster – Cliff Pond @ Main (Harmful Cyanobacteria Bloom)
• Danvers – Sandy Beach (Bacterial Exceedance)
• Dartmouth – Moses Smith Creek (Bacterial Exceedance)
• Eastham – Salt Pond (Bacterial Exceedance)
• Falmouth – Wood Neck River (Bacterial Exceedance)
• Freetown – Freetown Town Beach (Bacterial Exceedance)
• Holden – Eagle Lake (Bacterial Exceedance)
• Manchester – Black Beach (Bacterial Exceedance)
• Nahant – Black Rock (Bacterial Exceedance)
• Nantucket – Sesachacha Pond (Harmful Cyanobacteria Bloom)
• Provincetown – 333 Commercial Street (Bacterial Exceedance)
• Provincetown – Johnson Street (Bacterial Exceedance)
• Provincetown – Kendall Lane (Bacterial Exceedance)
• Provincetown – Town Landing – Breakwater (Bacterial Exceedance)
• Provincetown – Town Landing – Snail Road (Bacterial Exceedance)
• Quincy – Broady (Baker) Beach (Bacterial Exceedance)
• Quincy – Merrymount Beach (Bacterial Exceedance)
• Salem – Children’s Island – Back (Bacterial Exceedance)
• Salem – Children’s Island – Wally (Bacterial Exceedance)
• Salem – Ocean Avenue Beach (Bacterial Exceedance)
• Salem – Willow Avenue Beach (Bacterial Exceedance)
• Saugus – Pearce Lake @ Breakheart Reservation (Bacterial Exceedance)
• Saugus – Peckham Pond @ Camp Nihan (Bacterial Exceedance)
• Springfield – Camp Wilder @ Right (Bacterial Exceedance)
• Swampscott – Kings Beach (Bacterial Exceedance)
• Swansea – Coles River Club off Harbor Road (Bacterial Exceedance)
• Templeton – Beamans Pond Campground (Bacterial Exceedance)
• Templeton – Beamans Pond Day Use (Bacterial Exceedance)
• Tisbury – Owen Little Way (Bacterial Exceedance)
• Townsend – Pearl Hill Pond Beach (Bacterial Exceedance)
• Wareham – Briarwood Beach (Bacterial Exceedance)
• Wareham – Standish Shores (Bacterial Exceedance)
• Winthrop – Donovans Beach (Bacterial Exceedance)
• Winthrop – Pico Beach (Bacterial Exceedance)
• Worcester – Lake Quinsigamond, Lake Park Beach (Bacterial Exceedance)

Why Beaches Are Closed

Health officials said elevated bacteria levels are the primary reason for the closures. Contamination often occurs after heavy rainfall but can also result from sewer overflows, faulty septic systems, wildlife, pet waste and agricultural runoff. Three locations — two in Brewster and one on Nantucket — were closed due to harmful cyanobacteria blooms, which can pose serious health risks to people and pets.

The Massachusetts Department of Public Health updates its beach water quality dashboard regularly as new water samples become available.

Several beaches in Brewster and Nantucket were closed because of harmful cyanobacteria blooms, while the remaining locations were largely affected by elevated bacteria levels.

Provincetown reported five swimming closures, while Salem, Saugus and Winthrop also had multiple affected beaches.

Health Officials Urge Caution

Authorities advise residents and visitors to avoid swimming at beaches under advisory until water quality returns to safe levels. Beach closures are lifted only after follow-up testing confirms bacteria levels have fallen below public health thresholds.

Officials recommend checking the Massachusetts Department of Public Health’s beach water quality dashboard before visiting any swimming area, as advisories may change daily depending on testing results and weather conditions.