Swimmers are welcome back into the surf of a beach at Sandy Hook after bacteria levels that closed it Tuesday backed down — but other several beaches remain closed.

In a short message on its Facebook page, the Gateway National Recreation Area at Sandy Hook posted that Gunnison Beach was open for swimming on Wednesday.  The water was previously closed to swimmers due to an elevated bacteria level although the beach, which is New Jersey's only legal clothing-optional beach, remained open.

Several beaches in Ocean County were closed on Wednesday, including the beach at Ocean County Park in Lakewood, due to two rounds of heavy rain on Monday.

"After a very heavy rain, we tell people to not swim for 24 to 48 hours in our bays, rivers, lakes and creeks" because of a high level of bacteria that comes in, Ocean County Health Department spokeswoman Leslie Terjesen said.

Sandy Hook beach (Townsquare Media NJ)

The Low and High beaches at Harry Wright Lake in Manchester and the beach at Summit Avenue in Island Heights were closed on Tuesday. Their status had not been updated on the Health Department website as of 11 a.m. on Wednesday.

In Ocean County, Terjesen said, if the water tests with a high bacteria count,  an advisory is posted.

"If it's high the second day we close the beach (and) don't reopen it until the bacteria level is within normal range, and we do a sanitary survey to see where the bacteria might be coming from," Terjesen said.

Water is sampled by the county at 70 to 80 beaches almost daily and staffed with lifeguards, according to Terjesen, who advised that swimmers use only those facilities.

The NJ Department of Environmental Protection closed the Pittsburg Ave beach in Cape May because of a local sewer problem, according to spokesman Larry Hajna. In general, those waters have been clean, Hajna said, noting recent stories about how clear and blue the ocean water appeared.

Hajna said the DEP started posting beach condition advisories and closures online several years ago. Like Ocean County, it will close a beach if two tests comes back with a higher-than-normal bacteria level.

"Ninety-nine percent of the time elevated levels of bacteria are because of a storm passing through," Hajna said — adding most beaches will pass on a second test. Animal feces can also cause an increase, he said.

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