Enough wastewater to fill more than two Olympic swimming pools emptied into northern Tampa Bay Wednesday after a mishap during maintenance at a Clearwater treatment plant.

City officials told the Tampa Bay Times they had to divert an estimated 1.4 million gallons of partially treated wastewater into the bay after a settling tank designed to remove solids from water became overloaded.

Staff at Clearwater’s east treatment facility took water quality samples and “immediately began to assess any potential environmental impacts” after the spill, Rob Simpson, a Clearwater spokesperson, said in an emailed statement. As of Friday, there was no public health risk, he said.

Simpson said the “unanticipated process” happened during regular maintenance, when one settling tank was temporarily down for cleaning and a second tank became overloaded.

That caused solid matter to clog filters and plant workers opted to send the wastewater through a pipe that empties into the bay until the tank came back online, Simpson said.

Plant employees reported the spill to state environmental regulators who track pollution events across Florida’s 67 counties. The report says the issue was detected Wednesday night, and staff solved the problem by Thursday morning.

The city plant where the spill occurred is located on the western end of the Courtney Campbell Causeway. The wastewater emptied into Old Tampa Bay, a section of the estuary that is now seeing a historic-low amount of seagrass after losing more than 320 acres over the past two years.

Seagrass is considered a “canary in the coal mine” for the health of the Tampa Bay estuary as the aquatic plant helps stem pollution and fends off coastal erosion. Old Tampa Bay faces a range of threats, from pollution to slow-moving tides that aren’t doing enough to flush out dirty water.

That part of the bay has 23% less seagrass than when tracking began there in 1988, according to recent survey results from the Southwest Florida Water Management District.

“There’s places in Old Tampa Bay where there were lush seagrass beds for a number of years, and now it’s barren,” Ed Sherwood, executive director of the Tampa Bay Estuary Program, told the audience at a recent Tampa Bay Times water quality discussion.

As a standalone event, 1.4 million gallons of wastewater is on the high end of volume from recent one-off spills that have plagued the bay.

But as Florida’s largest open-water estuary, the waterway saw an influx of pollution after back-to-back hurricanes last fall. The estuary program estimated more than 40 million gallons of combined sewage overflowed in October as a hurricane one-two punch overwhelmed the region’s wastewater facilities.