If you want safer swimming areas with less bacteria, don't feed the ducks, geese or gulls on the beach, according to Sonya Carlson of the state Department of Environmental Services.

Bird feces is a major suspect in all of the recent incidents in which fresh-water beach advisories were posted because bacteria samples exceeded state standards for fecal bacteria, Carlson said.

Dog and human feces can also contribute to the problem, she said.

Septic problems could also be an issue, but those sample bacteria numbers would be much higher and haven’t been seen in recent years, Carlson said.

As of Friday night, the DES website posted three beach advisories: Arlington Pond Improvement Association Beach in Salem, Robinson Town Beach in Hudson, and Hedgehog Pond Town Beach in Salem.

The website is updated daily during the swimming season.

Carlson said Ahearn State Beach in Laconia was removed from the advisory list on Friday because the weather had been dry for 24 hours.

Ahearn is the only beach in New Hampshire that is routinely posted whenever it rains more than a quarter-inch in six hours, she said.

Carlson believes that problem may be caused by geese depositing feces on a grassy area that washes into the lake when it rains.

Carlson, beach program coordinator, said the state tests about 173 state, municipal and private fresh water lakes a year. The state pays for a staffer to collect the samples, and the beach owners or managers pay for the tests.

E. coli in the water can cause gastrointestinal problems such as diarrhea and vomiting.

New Hampshire is about on par with the last two years, with eight advisories posted in the DES website so far. She expects by the end of the season there will be about 50 or 55, not unlike the number last year, when there were 52. In 2010, there were 57, and in 2009 there were 60.

Advisories are posted at beaches if the fecal bacteria count per 100 millileters of water is higher than 88. It is up to the beach owner or manager to decide whether the beach should be closed.

“If it is above 88, about eight people out of a thousand would get sick from it,” Carlson said.

Children and people with compromised immune systems are most likely to become ill from such water.

“If you are completely healthy and not drinking the water and washing your hands after swimming, even if the count is high, you probably won’t get sick,” Carlson said.

Kevin Dunleavy, Laconia’s director of recreation, said Weirs Beach has had three days under a beach advisory so far this summer.

“It’s a difficult problem to solve,” Dunleavy said. “As far as waterfowl, I am not convinced it is just waterfowl. It could be storm water runoff or an illicit sewer connection.”

Dunleavy hopes to get a grant to determine how to prevent the need for such advisories in the future.

People may play a role, as well, he said, because Weirs Beach serves 500 to 1,000 people on a busy day.