Sewage treatment plants in many U.S. towns and cities have trouble during heavy rain events, when “combined flows” overwhelm the capacity of the plant and force the operators to dump untreated sewage into waterways. The problem is that the same municipal pipes have to handle stormwater runoff from streets and properties, along with sewage from homes and businesses. When there’s too much rain, the plants can’t keep up. It’s a serious issue for coastal communities, where sewage discharges can make beaches unsafe and contaminate shellfish harvesting areas.

Authorities aren’t sure, but that may be what happened in Hull, Massachusetts last week, when a sewage treatment plant flooded, forcing the release of 2 million gallons of sewage into the Atlantic Ocean, the Patriot Ledger reported (“Water surge knocked out Hull's sewage treatment plant,” by Neal Simpson).

“Emergency management officials rushed to get portable pumps in place Thursday morning after electronic monitors detected a ‘very unusual’ volume of water flowing into the plant between 1 and 2 a.m.,” the paper reported. “The surge overwhelmed the plant’s pumps and flooded the basement, forcing officials to shut the plant down.”

“Crews have installed pumps and pipes to divert wastewater out of the sewer system,” the Boston Globe reported on March 1 (“Shutdown persists at Hull wastewater plant; sewage pours into Atlantic for second day,” by Lauren Dezenski). “The water is now being pumped through a manhole, over a rocky area on the beach, and across a stretch of sand into the bay.”

Bruce Berman, a director with environmental group Save the Harbor/Save the Bay, told the Globe that a discharge of 2 million gallons was “not the end of the world.” “Not so long ago, we were discharging 200 million gallons of largely untreated sewage into the Boston Harbor every day,” he said. “However, it’s never good to dump raw sewage into the water.”

The plant was back on line within a few days, the Patriot Ledger reported (“Sewage no longer pumped into water; Hull plant shutdown still being investigated,” by Christopher Burrell). Problem solved, for now — but citizens remain unhappy. Angela Sanfilippo, executive director of the Massachusetts Fishermen’s Partnership, told the Patriot-Ledger: “My whole feeling is this is not good for the ocean, bottom line.”