Swimming at state beaches might be discouraged more often in coming years.
New federal guidelines issued this week by the Environmental Protection Agency may force the state to update the standard it uses to measure water quality at beaches, potentially resulting in more red flags to alert swimmers to unsafe conditions. The warnings would be required when bacteria counts are as much as 40 percent lower than what the state considers safe today.
The state would be obliged to follow the new regulations, which would take effect in 2016, if it wants to continue receiving nearly $250,000 in federal aid for monitoring water quality at beaches. The state could also qualify for an exemption if it persuades federal officials it has a better way to monitor bacteria in water.
The rules are “intended to strengthen protection of the health of America’s beachgoers through safer water standards, improved beach monitoring, and better notification of advisories or closures,” said Emily Zimmerman, an EPA spokeswoman.
She said the rules would help improve identification of the sources of fecal pollution and encourage same-day notification when the bacteria exceeds the new standards for safe swimming. The state now considers it unsafe to swim when a single sample is found to have 104 bacteria-colony-forming units per 100 milliliters of water; the new standard would lower that threshold to 60 or 70 units, depending on what the state chooses as its standard.
Officials from the state Department of Public Health declined to answer questions about the new federal standards.
In a statement, Suzanne Condon, the department’s associate commissioner, said: “We are in the process of reviewing these new guidelines to determine whether our current regulatory standards should be amended.”
She added that federal aid for the state’s beach program “is critical to our overall efforts on beach water quality monitoring.”
Massachusetts has 571 public and semipublic beaches along 204 miles of Atlantic coast.
Last year, 6 percent of samples collected from 497 Massachusetts beaches exceeded the state standard for safe swimming, according to a report of the nation’s beaches released this year by the Natural Resources Defense Council, an environmental advocacy group based in New York. If those beaches had used the new federal standard, 10 percent of the samples would have triggered red flags, according to the report.
Fifty-seven state beaches had samples that would have exceeded the new federal standard more than 20 percent of the time.
“New scientific evidence has shown that public health is at risk above the levels” when bacteria counts are higher than the new standards, said Steve Fleischli, the water program director of the Natural Resources Defense Council. “If states want to do right by the public and protect them from swimming with bacteria, they’ll use this” standard.
Swimming at beaches with higher levels of bacteria — often the result of sewage overflows or runoff from roads — could lead to stomach distress, ear infections, pink eye, fever, diarrhea, and neurological disorders.
In the Boston area, where state officials have spent years and some $5 billion cleaning the waters off local beaches, officials and advocates are sensitive to changes that might curb the number of days when it is considered safe to swim.
Just this year, state officials began using a new water-monitoring policy in an effort to reduce the number of unnecessary beach closures. They estimated some 80 percent of beach closings over the past 13 years were unnecessary, mainly because the samples were taken the day before officials posted red flags.
At most of the state’s beaches, the new policy requires samples taken from two consecutive days to show elevated levels of bacteria before any action is taken. Those with a history of high bacteria counts can still be closed after one sample exceeds the current standard.
Bruce Berman, a spokesman for Save the Harbor/Save the Bay in Boston, said few beaches along Boston Harbor would be significantly affected by any change in standards. But he said those beaches with a history of high bacteria counts, such as Wollaston in Quincy, King’s in Lynn and Tenean in Dorchester, would be closed more often under the federal standard.
He argued that state officials should focus more on the amount of rain than on collecting samples.
“The pollution is almost always associated with rain,” he said. “That would also allow us to not have to wait for a test. We could post the flags right away, based on how much rain we have.”
He said the state should use years of data about how much rain causes elevated bacteria counts at specific beaches, rather than applying a blanket new standard. He said he expects the state to seek an exemption.
If the state chooses to apply the new standard, he said, that will mean more beach closures.
“I am definitely concerned more beaches will be flying red flags — and more wrong red flags — and that’s not a good thing,” he said. “It could be a dramatic and inappropriate increase. It would be based on yesterday’s test results.”