The Rhode Island Department of Environmental Management preemptively closed 700 acres of shellfishing grounds on the north side of Prudence Island on Saturday because of a large, planned gathering of recreational boats.

Known as “Aquapalooza,” the informal and unauthorized event brought more than 1,000 boats to the area last weekend, according to DEM spokesperson Michael Healey. The organizers are anonymous, and the day is arranged through social media around the same time as the Newport Folk Festival, when there is a large police presence, drawing attention away from the watercraft activities, Healey said.

“Although most recreational boaters follow Rhode Island’s ‘No Discharge’ law, a high concentration of vessels increases the chances of accidental or illicit discharge of sewage into shellfish waters,” according to a recent DEM press release.

The U.S. Food and Drug Administration has rules against shellfishing in marinas and areas like it, and “the north shore of Prudence effectively becomes a densely packed mooring field,” Healey wrote in an email to ecoRI News.

Although there was some law enforcement presence at the event, monitoring for sewage dumping would have been difficult, according to Healey.

“Given the number of boats inside a small harbor and the fact that, mainly, law enforcement is patrolling to prevent drinking-related disasters, it would be impractical to monitor for illegal dumping — too many boats rafted together, very hard to distinguish which boat might be dumping,” he wrote.

The closure began July 29 and will continue until sunrise Aug. 5, which Healey said should be enough time to dilute any contamination from Aquapalooza. The closure includes all of Potter’s Cove, according to DEM.

Mike Lombardi, a shellfisherman who usually works out of the cove, said he was surprised and upset about the closure.

Lombardi said he and others who shellfish are used to closures due to rain and other naturally occurring events that worsen water quality, but closing for something man-made is frustrating.

“Shellfishing is one of the Rhode Island traditions that we are proud of,” he said, “but now we are saying we’re going to let this party go.”

He said the closure was “completely backwards.”

Although there are other places he could fish, “there’s a lot that comes with being displaced,” he said. A fisherman develops a routine in an area that maximizes their efficiency and profits.

He said he is one of several fishermen that is impacted by the closure.

“A bunch of us are working the area pretty hard this summer,” said Lombardi, explaining that there are usually 10 shellfishing boats in the area on a busy day.

The closure will likely cause him to miss out on $1,500 to $2,000, he said.

In addition to fishing, Lombardi is also a diver and has been called by folks who have gone to Aquapaloozas in the past and lost something overboard. He said there will likely be trash and debris either accidentally or purposely tossed into the cove from the event.

“Potter’s Cove is a relatively closed body of water,” he said. “Everything gets stuck in there.”