A total of 12 New Hampshire bodies of water are under advisories that recommend humans and pets do not swim or wade in them.

The New Hampshire Department of Environmental Services put four of the state’s beaches under fecal bacteria advisories in the last week.

Over the same time period, the department put four other bodies of water under blue-green algae warnings, bringing the total number of lakes and ponds under such warnings to eight.

All in all, the department recommends avoiding swimming or wading in 12 different New Hampshire bodies of water.

Fecal bacteria advisories

The Environmental Services Department issued the first fecal bacteria advisory on Aug. 2 for Clough State Park Beach in Weare. The next day, it added Griffin Beach in Franklin and North Hampton State Park Beach in North Hampton to the list. Finally, on Aug. 4, it issued an advisory for Pirate’s Cove in Rye.

The department regularly tests beaches for fecal bacteria, and issues advisories when they reach unsafe levels, it said on its website. Once an advisory is issued, the department tests the beach every day until the amount of bacteria returns to a safe level.

Beaches can accumulate high levels of fecal bacteria when rainwater encounters human or pet waste before it empties into a body of water. Exposure to the bacteria can cause humans and pets to suffer nausea, vomiting, diarrhea, and fever.

Blue-green algae warnings

The Environmental Services Department issued a blue-green algae warning for Showell Pond in Sandown on Aug. 1. The next day, it issued a warning for Northwood Lake in Northwood, and on Aug. 4, it issued warnings for Captain Pond in Salem and Mascoma Lake in Enfield.

The four bodies of water joined three others the department issued blue-green algae warnings for the week before — Hunkins Pond in Sanbornton, Arlington Mill Reservoir in Salem, and Tucker Pond in Salisbury. In early July, it issued a warning for Province Lake in Effingham.

The department regularly tests bodies of water for cyanobacteria levels, commonly known as blue-green algae, it said on its website. Once a warning is issued, the department tests the body of water weekly until the cyanobacteria bloom subsides.

Exposure to cyanobacteria can cause gastrointestinal problems, fever, and dizziness, among other symptoms, according to the CDC. Animals can also get sick, it said, and sometimes die.

The department is currently watching cyanobacteria blooms at Alton Bay on Lake Winnipesaukee in Alton, Deering Reservoir in Deering, and Little Sunapee Lake in New London.

Checking for beach advisories

For up-to-date information on New Hampshire swimming advisories and alerts, visit the Department of Environmental Services’ beach map.

The Massachusetts Department of Public Health now also makes this information publicly available on Mass.gov.