To DEM: Reduce pollution by wastewater treatment facilities
by Mike Jarbeau, Narragansett Baykeeper
As part of our work at Save The Bay, we review local, state, and federal permit applications that affect Narragansett Bay, including virtually all applications sent out to public notice by the Department of Environmental Management (DEM) and Coastal Resources Management Council, among others. And right now, we’re reviewing discharge permits for three of Rhode Island’s larger wastewater treatment facilities – Cranston, Warwick, and West Warwick – that are up for renewal by DEM. These permits authorize facilities to release the byproduct from the wastewater treatment process into the Bay, with limitations on the amount of nitrogen and other pollutants in the discharge. We are urging DEM to add stricter limits to these permits, to move us closer to meeting water quality standards in Narragansett Bay.
The negative effects of too much nitrogen
Over the past century, improvements in wastewater treatment technology and infrastructure have significantly reduced bacterial pollution in our Bay. More recently, attention has turned to the nitrogen contained in wastewater discharge. Excess nitrogen fuels the growth of algae, which in turn uses up oxygen in the water during decomposition. This process threatens fish and shellfish, causes foul smells, affects the beauty of our waters and degrades important habitat such as eelgrass.
The impacts excess nitrogen on the Upper Bay have been documented since the 1980’s. In 2004, under pressure from Save The Bay and others, DEM began to require wastewater treatment facilities to reduce the amount of nitrogen in their discharge, with a long-term plan to phase-in stricter limits over time.
Currently, the Cranston, Warwick, and West Warwick facilities treat an average of 23 million gallons of wastewater per day, with nitrogen limits of 8 milligrams per liter of water (mg/l). They account for about 18 percent of Rhode Island’s total wastewater discharge. By contrast, Fields Point and Bucklin Point, the two largest treatment facilities in Rhode Island, have nitrogen limits of 5 mg/l; they often discharge at less than 4 mg/l. The discharge from these facilities has a big impact on water quality. Rhode Island has a responsibility under the Clean Water Act to issue permits with the goal of eliminating water pollution.
Now is the time for reduction
Save The Bay has generally supported DEM’s phased approach to nitrogen reductions. But the time has come to take the next steps. Our Bay remains impaired, as was clearly illustrated in the Narragansett Bay Estuary Program’s State of Narragansett Bay and Its Watershed report. On top of that, climate change continues to accelerate, stressing the Bay and compounding the effects of pollution. The best available science and modeling indicates that a reduction in nitrogen limits to 3 mg/l, currently considered the limit of treatment technology, is necessary and possible. As DEM reissues the permits for the Warwick, West Warwick and Cranston wastewater treatment plants, we are urging them to implement a 3 mg/l nitrogen limit.