Signs at the entrance to the East End Beach on Sunday tell beachgoers that it is temporarily closed. Portland officials closed the beach Sunday afternoon after a malfunction at the nearby wastewater treatment facility. The beach will remain closed until the water levels are tested to determine if it is safe, the city said. Brianna Soukup/Staff Photographer

Portland officials closed the East End Beach on Sunday after being notified by the Portland Water District of a “malfunction” that occurred at the nearby East End Wastewater Treatment Plant.

Jessica Grondin, spokeswoman for the city of Portland, said the popular beach will remain closed until test results prove that the water conditions are safe for swimmers.

The closure took place after a Central Maine Power line that feeds electricity to the plant shut off around 8:15 a.m. Sunday, according to Scott Firmin, director of the wastewater treatment plant. Further complicating the power outage was a backup generator at the plant that failed to generate power.

As a result, an undetermined amount of wastewater discharge left the plant and entered Casco Bay, but was not completely disinfected, Firmin said. Power was restored around 2:30 p.m. and a rented portable generator was brought in as a safety precaution.

“Our disinfection system was interrupted and out of an abundance of caution I made a call to the city and notified them,” Firmin said Sunday night.

The Maine Department of Environmental Protection was also notified. Firmin said he must file a report with the DEP explaining what happened at the plant by Friday. He said the decision to reopen East End Beach will be up to the city after test results are analyzed.

The Portland Water District owns and operates the treatment plant, which serves 60,000 people and handles an average of 20 million gallons of water each day.  The water district says its facility, located just to the west of the Interstate 295 bridge between East Deering and Munjoy Hill, is the state’s largest.

Sunday’s beach closure represents the second time in two years that malfunctions at the treatment plan have forced the city to shut down East End Beach.

On July 26, 2018, the city temporarily closed East End Beach because a disinfection tank was not put back on line after being cleaned and a second tank was overwhelmed by high flows caused by heavy overnight rains. When the tank overflowed, about 1.69 million gallons of partially treated wastewater spilled, flowing down an embankment and entering Casco Bay west of East End Beach and the boat launch.

The 2018 event also washed out the section of the Eastern Promenade Trail that abuts the treatment plant. The Portland Water District blamed the spill on human error. Repairs to the walking trail and treatment facility cost between $30,000 and $50,000.