A sewage spill at the pump station at the end of the Stonebridge in Onset has necessitated the closure of some beaches and a temporary ban on shellfishing in Onset Bay.

Just after 2:30 p.m. on Sunday, July 5, Water Pollution Control Facility crews were working to un-clog the pumps. While they worked, the level in the wet well rose and needed to be released. The crews turned on both pumps, instead of just one (which is the usual practice), and between five gallons and 2,500 gallons of sewage overflowed into the bay.

The situation is compounded by the tide, which is currently coming in and corralling the waste close to shore. 

All beaches within Onset Bay have been closed as a precautionary measure.

Additionally, shellfishing is temporarily banned within Onset Harbor from an imaginary line drawn from Sias Point to Codman’s Point and all points North within Onset Harbor.

The WPCF took samples of the water on July 5 to test for fecal chloroform, but the results were inconclusive. That means that new samples had to be taken and processed.

The determination of when shellfishing can resume is up to the State Department of Marine Fisheries.

Guy Campinha, the director of the WPCF, said that the clog crews were working on was the result of people flushing baby wipes and cleaning wipes down the toilet, which they are not supposed to do.

“I need the public to stop flushing things other than toilet paper,” Campinha said. The sewer system cannot handle the wipes, which stick together to create clogs in the pipe or around the pumps. Those clogs take time to fix, and damage the pumps themselves. That damage shortens the life of the pumps, and replacement is expensive.

Campinha said that flushed wipes have been an increasing problem over the past several months. On Sunday, a short-staffed team had eight clogged pumps around town to fix. 

The wipes have also started to cause problems at the main water treatment plant. 

Campinha said the situation is a “nightmare.”

The leak was not related to the pipe replacement on the bridge in 2011.