A combined sewer overflow empties into Portland Harbor below Commercial Street located between Dimillo's wharf and Portland Lobster Co. CSOs like this harm marine life and risk public health. (Courtesy Friends of Casco Bay)
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White bacteria grows at the bottom of a large combined sewer overflow pipe that empties into the waterfront along Commercial Street between the DiMillo’s parking lot and Portland Lobster Co. 

The outflow is only visible after strong storms and at very low tides. But along the adjacent wharf, the smell of raw sewage gives it away. 

The Portland Water Resources Department has been working to reduce CSOs like this since 2016. The work is scheduled to conclude in September 2022, at a cost of more than $68 million.

This illustration depicts Portland’s various underground water and sewage pipes. (Courtesy Friends of Casco Bay)

“Millions of gallons of CSO raw sewage is the big insult to the bay all the time,” Friends of Casco Bay Baykeeper Ivy Frignoca said. “There should never be raw, untreated sewage going into our water.” 

CSOs carry stormwater and sewage. When the city gets a lot of rain, its system of pipes becomes overwhelmed and can’t handle the volume of sewage and stormwater. The overflow of untreated sewage and stormwater is released into the waterways. 

“CSOs are a huge issue for two reasons: public health and the environment,” Will Everitt, the communications and development director for Friends of Casco Bay, said. “It’s a public threat to have raw sewage bacteria in the bay and it’s not great for the animals and plants that depend on the bay.”

Friends of Casco Bay has been meeting with the city quarterly to get updates on the city’s progress and plans. 

Frignoca has been the baykeeper for six years and said CSOs and water quality are her priority. She has contributed to an Integrated Plan that provides requirements to make sure water quality testing is being done in a way that reduces pollutants.

“My job as Casco baykeeper is to be the voice of the bay,” Frignoca said. “And to do everything that I can possibly do to improve and protect its water quality.” 

The Integrated Plan is being worked on by the city and the state to become a permit to enforce the requirements from several other documents into a single set of guidelines and goals. 

An aerial photograph of construction work at the Back Cove South Storage Facility near Preble Street and Interstate 295 in Portland. Work is scheduled to be complete by September 2022. (Courtesy city of Portland)

“This was really the best thing for Portland to do,” Frignoca said. “It was the best use of taxpayers’ dollars and it was the best way to improve water quality.” 

The plan identifies more than 100 water quality projects to address stormwater runoff and impaired waterways. The permit will be ready by the end of the year, but “there is still lots of stuff the city can start on,” Nancy Gallinaro, water resources manager, said. 

There are four ways the city has already gotten started. 

First, it is cleaning out the old pipes. The garbage and debris that has been found “eliminated part of the problem” because there’s now more volume and less need for overflow, Frignoca said. 

Also, research on the condition of existing infrastructure is being carried out, Brad Roland, senior project engineer for the Water Resources Department, said, by looking for water coming through holes or cracks in old pipes.

Next, the city is separating the stormwater and sewage pipes so there are fewer combined overflow pipes. 

The fourth tactic is construction of storage conduits around Back Cove and Interstate 295. The conduits collect polluted rainwater and combined sewage overflow, Frignoca said. 

“They’re doing a really hard job,” Everitt said. “They’re doing this work on behalf of all of us.” 

The Back Cove South Storage Facility will hold more than 3 million gallons of stormwater when it is complete. (Courtesy city of Portland)

The Back Cove South Storage Facility, along Preble Street and Baxter Boulevard, will hold 3.5 million gallons of untreated water from three CSOs. The Back Cove West Storage Facility, on Baxter Boulevard between Payson Park and Vannah Avenue, will hold 2.25 million gallons from two other CSOs, Roland said. The water will be held in the conduits until it can be sent to the East End Wastewater Treatment Facility for processing. 

The U.S Environmental Protection Agency says CSOs release about 850 billion gallons of untreated sewage and stormwater to waterways. The EPA has developed a control plan to help with the reduction of CSOs across the country. 

“They are very active in our planning and care deeply about Maine’s environment,” Gallinaro said. “Our long-term goal is to have people enjoy the water.” 

Portland Water District manages the greater Portland’s public water supply. It also owns and operates the East End Wastewater Treatment Plant. 

The city and PWD work together to “assure water quality remains our first priority,” Gallinaro said. “From maintaining existing systems to rehabilitating infrastructure, everything is to keep the dirty water in the pipes.” 

CSO activity dropped to 179 million gallons last year compared to the billions of gallons it totaled before, Roland said. 

With a plan in motion, officials are optimistic that the work they’re doing will make a difference.

“Our city (is) around this beautiful body of water for a reason,” Everitt said. “We want to stop raw sewage in the bay and we want to stop pollution.”