The Westerly Sun • 1/19/2015
STONINGTON — Water quality in Fishers Island Sound is strongly impacted by tidal flushing, according to a study from one local environmental group.
Clean Up Sound and Harbors’ six-year study of water in the sound found significant change in water quality as a result of specific flushing. Summer algae levels were generally too high, except for the well-flushed Stonington Harbor. Inland, however, water quality was rated “poor” in Pequotsepos and Wequetequock coves.
The results were released on Jan. 19 as part of one of the most thorough evaluations of Stonington coastal waters.
Water quality was monitored at 12 sites in four locations: Stonington Harbor, the Mystic River, and Pequotsepos and Wequetequock coves. Samples were evaluated for fecal bacteria, dissolved oxygen, and organic and inorganic nitrogen. These pollutants are related to stormwater runoff, chemical fertilizers, poorly designed or overloaded septic systems, wildlife waste and high-impact development.
Summer levels of inorganic nitrogen, a major reason for algae blooms and oxygen depletion, were generally excessive in the inland locations. In turn, low oxygen levels were observed which could harm the aquatic environment.
The study reinforced the idea that nitrogen pollution in the area primarily originates in multiple and widespread sources rather than specific businesses or facilities.
Overall water quality was good throughout Stonington Harbor, good to fair-plus at the mouth of the Mystic River, fair-minus in the center of the Mystic River, and poor in Pequotsepos and Wequetequock coves.
Results outside Stonington Borough reflected a greater tidal influence; samples taken at Sandy Point, mid-harbor, Dodson Boatyard and Lambert’s Cove were all classified as “good.” Testing was led by the organization’s water testing director, Claire Gavin.
“When estuaries are well flushed with oxygen-rich water, as in Stonington Harbor and the Mystic River, aquatic life can be well-supported even in the presence of nitrogen pollution, as long as nitrogen input does not overwhelm the flushing capacity,” said Gavin in a press statement. “When both fresh and saltwater flows are weak, as in our flow-restricted coves, poor flushing allows pollutants to accumulate, and good water quality can only be achieved by limiting the amount of nitrogen that enters the water.”
In Mystic, water quality at Ram Point on Masons Island was rated “good,” while samples at Mystic River Park and Murphy’s Point were observed at “fair.”
In Pequotsepos Cove north of Route 1, water samples showed “poor” quality. Samples taken south of the railroad bridge fared better, meriting a “fair” rating.
The head of Wequetequock Cove was sampled near the intersection of Route 1 and Greenhaven Road, from the Stonington Marina. The cove has consistently had the lowest water quality of any sampling. At times the site showed evidence of acute hypoxia or lack of oxygen.
South of the railroad bridge, water quality was rated as “fair.”
“Healthy water is key to our community’s vitality from a business, recreational and quality of life perspective,” said Frances Hoffman, a past president of the environmental group. “While some causes of pollution are beyond our control, it is well within our power to reduce nitrogen pollution.”
As part of the report, CUSH included a section on stewardship, listing various pollutants and everyday actions the public can take to remedy their influence. These actions include mowing your lawn to no less than 3 inches, and using boat pump-out facilities.
The report, “Water Quality of Four Estuaries in Coastal Stonington and Mystic Connecticut, 2008-2013,” was made available on the CUSH website (www.CUSHinc.org).
