Groton ― Town officials continued Monday to search for the cause of contamination in the waters off Morgan Point in Noank.

Late Monday afternoon, Town Manager John Burt said the level of fecal coliform found last week in the vicinity of the Noank Town Dock was not as high as originally thought. The level had prompted Ledge Light Health District to recommend Friday that the area be closed to swimming.

While bacteria was detected in water in a catch basin near the dock, water tested near a nearby outfall site on the beach was free of contamination, Burt said.

In any event, he said, the ban on swimming will remain in place until further notice.

Burt said officials are continuing to narrow down the source of the contamination by process of elimination. Catch basins around a property at 182 Pearl St., a suspect at one time, have been eliminated as a possible source, as have other sites, he said, with the focus Tuesday scheduled to shift to Abbott’s Lobster in the Rough restaurant and the Noank Shipyard.

Town staff began preparing for dye testing at those locations, a process that could reveal leaks.

In addition, Burt said he’s asked state officials to examine pumpout boats and marina pumpout facilities that remove and process waste captured on boats.

Ted Rathjen, a Groton Shellfish Commission warden and superintendent of the Noank Water Co., said earlier Monday that the contamination could be related to a recent period of heavy rainfall and could involve “a very simple problem.”

“We haven’t found anything to date that leads us one direction,” he said. “We’re still looking in multiple locations.”

Mystic Oysters, one of a handful of oyster farms operating in waters off Groton and Stonington, brought the contamination to Groton officials’ attention nearly a month ago after discovering it during routine testing of oysters.

Subsequently, the state Department of Agriculture issued a “precautionary closure” of certain oyster beds and advised against the consumption of oysters harvested in those areas from Aug. 28 to Aug. 30. No harvesting has taken place there since then.

“Obviously, it’s an urgent matter, particularly for the harvesters who are in a hard place financially,” Burt said.

b.hallenbeck@theday.com