WILTON — A study of 16 Fairfield County rivers, including four in Wilton, has turned up disturbing information in terms of water quality, specifically contamination by E. coli and Enterococci bacteria.

The study, the 2019 Fairfield County River Report, was issued Dec. 10 by Harbor Watch, the water quality research program of Earthplace of Westport.

The study found that 77 percent of the 123 field stations studied in 16 towns exceeded either one or both of the state criteria for acceptable levels of the bacteria which may indicate sewage pollution. Of the 16 rivers tested, the Silvermine River and Belden Hill Brook in Wilton had the lowest percentage of failing sites at 50 percent.

The Comstock Brook had a failure rate of 67 percent and the Norwalk River, which had test sites in Ridgefield, Wilton and Norwalk, had 73 percent of sites fail.

One hundred percent of test sites failed along the Bruce Brook in Stratford and Bridgeport, Deep Brook in Newtown, Muddy Brook in Westport, Pussy Willow Book in Westport, and Sasco Brook in Westport, Fairfield and Easton.

The other rivers tested included Farm Creek in Norwalk; Horseneck Brook in Greenwich; Noroton River in Stamford, Darien and New Canaan; Pequonnock River in Monroe, Trumbull and Bridgeport; Pootatuck River in Easton, Monroe and Newtown; Rippowam River in New Canaan, Ridgefield and Stamford; and the Saugatuck River which flows through several towns.

Harbor Watch has been monitoring water quality throughout Fairfield County since 1986. The report indicates dozens of stormwater systems flow into the rivers throughout the 16 towns and, and with the help of local officials, multiple sources of sewage pollution that flows to the Long Island Sound watershed were identified. None were found in Wilton, however.

In addition to testing for bacteria, the teams of trained Harbor Watch employees also tested for dissolved oxygen, temperature and conductivity.

Oxygen is important for the survival of aquatic species, much as it is for humans and animals on land. Oxygen levels can be negatively impacted by organic material such as leaves and grass clippings decomposing at a river’s bottom. Oxygen levels are also lowered by stagnant water.

Conductivity is a measure of how easily the water can carry an electrical current, quantifying the intrusion of salt water or other sources of salt and other compounds in a waterway.

Temperature is also an important parameter for both for assessing habitat quality and detecting pollution.

Belden Hill Brook, Comstock Brook, and the Silvermine River had no test sites that failed the dissolved oxygen test. The Norwalk River had nine percent of sites fail.

Sarah Crosby, Ph.D., director of Harbor Watch, said of the results from Wilton, “we were happy to see relatively good water quality compared to some work in previous years in the Silvermine River and Comstock Brook.” She said there has been a lot of energy invested in the watershed and “we’re seeing that energy pay off for Comstock and Silvermine. We were pleased to see that compared to some of the others rivers and for Belden Brook as well.”

Overall, she said, “there is room for improvement and more that can be done. With more data, keeping the conversation going is so important. Without the information, we don’t know where to begin.”

Crosby said Wilton’s environmental director Mike Conklin was a partner in Harbor Watch’s work and the Norwalk River Watershed Association is also an important participant.

“Thanks to all our committed partners, we’re able to see improvement,” she said.

What people can do, even if they don’t live near a watercourse:

Properly maintaining a septic system is a major benefit.

Pet owners should pick up after their dogs, whether at home or away, and not place droppings into catch basins as these lead to waterways.

Be conscious how you are managing your property in terms of pesticides and feterilizers, opting for native plants over lawns.