Walden Pond is known for its beauty and tranquility, but it may have been a little too quiet for a few days last month, after beach-goers arrived to find bacteria warning signs urging them to stay out of the water near the main beach.
The signs are gone now, and with any luck they won't be back. But the weather has to cooperate, a state park official said.
Wendy Fox, spokeswoman for the state Department of Conservation and Recreation, said runoff from heavy rains had poured into the ocean, lakes, and ponds across the state in recent weeks, raising bacteria levels in the water.
Walden Pond was one of several state parks affected. High levels of bacteria were reported there on at least two days late last month, and many urban beaches in Eastern Massachusetts and lakes in the western part of the state still saw problems into early last week.
Fox said bacteria counts had returned to safe levels at Walden Pond last week, but things could change quickly. The water quality is tested on a weekly basis at state beaches, she said. If there's a high reading, officials will check the spot daily.
The state checks for a bacteria called enterococcus, which is typically found in the feces of humans and animals. Fox said if there is an enterococcus problem, it's usually an indicator of other harmful bacteria. These are not all life-threatening, but can cause gastrointestinal distress, she said.
The state doesn't close a beach if there are high levels of bacteria. Instead, signs are posted warning visitors to avoid water contact. Members of the public, however, can swim at their own risk, Fox said. That was the case at Walden Pond for those few days last month.
"We post signs, and lifeguards will tell people about the bacteria count," Fox said. "These are public beaches. People can go in if they want to. We encourage them not to."
Fox said the signs state that bacteria levels are high, but do not list the risks associated with swimming in the water. The state has a hot line that residents can call to check on the condition of beaches. If there are high levels of bacteria, the affected beaches will be listed on a recording. The recording urges swimmers to avoid water contact at those beaches because it may cause illness.
Fox said bacteria levels have been high in some ocean beaches, such as in South Boston, Revere, and Quincy. She said a few lake parks, including Regatta Point at Quinsigamond State Park in Worcester and several in Western Massachusetts, had some problems during the past week. Most problems clear up within a couple of days. "It's totally weather-dependent," she said.
Sometimes, the bacteria will affect only a small portion of the water body, Fox said.
At Walden Pond, the main beach had warnings, and signs directed beach-goers to the secondary Red Cross Beach.
On Wednesday, the warning signs were gone from the pond, and the beaches were already packed by midmorning with visitors.
The 102-foot-deep glacial kettle-hole pond is part of the Walden Pond State Reservation, which includes 462 acres of protected open space.
A total of 2,680 acres of mostly undeveloped woodland, Walden Woods, surrounds the reservation. The woods include hiking trails that ring the pond and a replica of the one-room cabin where Henry David Thoreau spent his time.
Lynne Dichter of Arlington was on the beach with her 6-year-old son. She said she likes the swimming area because it's close to home and is a manageable size to keep an eye on her son.
Dichter said she had heard about the bacteria problems at some of the state beaches and planned to keep an eye out this summer.
If signs are posted, she said, she plans to stay out of the water. Otherwise, she thinks it's safe.
"I'm fairly trusting that if the people here thought it wasn't safe, it would be closed," Dichter said. "If I saw a sign that they were concerned, I wouldn't go in."
Margaret Beal, who brought her two sons, ages 5 and 3, to Walden Pond last week for their first visit of the summer, said she likes Walden Pond because the water is calm for her little ones.
If a warning sign goes up, though, she said she would not use the beach and heed the warnings.
"There'd be no reason to risk it," Beal said. "We'd go back home and put the sprinkler on."
The hot line number for state beach water quality is 617-626-4972. The recording is updated daily.
Jennifer Fenn Lefferts can be reached at email@example.com.