By Desirae Sin
UConn Journalism
Freshwater rivers are vital to the lifecycle of many fish species, but pollution and overflows of sewage and wastewater can hurt these delicate processes.
Sewer overflows entering the Connecticut River and its tributaries can lead to die-offs of several valuable migratory fish species, including the American shad, Connecticut’s official fish, and several other species.
Shad spend much of their lives in the ocean, returning to rivers to spawn. Once hatchlings in the Connecticut River and its tributaries mature, they make their way to the Atlantic Ocean. The next season, they return to the rivers.
The Connecticut River Conservancy (CRC), a non-profit that monitors the full length of the Connecticut River in four states, advocates for clean water and educates residents about the river ecosystem. The CRC is based in Greenfield, Massachusetts. Its river steward for Connecticut, Rhea Drozdenko, said that migratory fish are a valuable part of the river’s health. These include the sea lamprey, shad, river herring, and American eel.
These fish spend part of their life in the Connecticut River and then they spend part of their life out in the Long Island Sound or in the Atlantic Ocean,” Drozdenko said. “Those fish are really important to our Connecticut River system because they bring back all these really important ocean nutrients.”
Despite the work by the Metropolitan District Comission to improve the quality of wastewater for Hartford residents, combined sewer overflows still occur and can have severe environmental impacts.
Combined sewer overflows (CSOs), carrying untreated human waste, other household waste, and runoff from roads, are discharged into tributaries like the Park River, which then join the Connecticut River. Although sewage treatement removes a lot of the nitrogen, the overflows contain nitrogen and phosphorus and can cause algae blooms. Algae feed off nutrients and can grow in great numbers. Eventually the algae must die, and when it does, the process of decomposition draws out oxygen from the water, leaving little for other wildlife like native fish.
The Connecticut Department of Energy & Environmental Protection maps public lakes, ponds and areas where fishing is allowed. Local fishermen may use these public bodies of water for recreational purposes, but these water bodies may be tributaries, in which CSOs enter.
“Sewage contains a lot of nutrients. We eat nutrients and we get rid of them, nutrients like nitrogen and phosphorus. Nitrogen and phosphorus are really important for the environmental life cycle, all plants need it. However, when it’s excessive, when there’s too much, it really causes problems,” Drozdenko said.
“You might not think that sewage in the water can eventually [lead to fish kills]. After all, these different steps lead to fish kills, but it can. It’s just all of these downstream effects,” she said.
The CRC tests water quality weekly from June through August each year to give residents a sense of whether the water is safe for swimming and boating.
Although raw sewage can cause fish deaths, contaminants within the water can lead to contaminated food and infections for humans. Biomagnification is the process in which contaminants can compound themselves in the food chain.
A common example of this phenomenon is mercury in certain ocean fish. Smaller organisms can absorb mercury through the water and other sediments, when those organisms are eaten, and then those ones are also eaten by bigger fish, the mercury remains and becomes more concentrated down the line.
By the time the food chain reaches some species humans eat — like salmon or tuna — the mercury reaches higher, potentially dangerous levels. This same concept can be applied to several contaminants within sewage from CSOs.
Map of fishing areas: https://experience.arcgis.com/experience/e02d8026889042c7aa2d71be67a72b9c
TOP IMAGE: American shad swim upriver every spring to spawn in the Connecticut River. Photo courtesy of Bill Byrne/ Massachusetts Wildlife