Water Quality Trends in the Connecticut River Watershed in Connecticut

Degradation of water quality in the Connecticut has been documented since the late 1800’s. Throughout the late 19th century and much of the 20th century, water-quality continued to be degraded. By 1930, the wastewater discharge to the basin from towns and cities in Massachusetts and Connecticut had reached 266,000 m3/d, with only about 20 percent of the effluent having some form of minimal treatment. By 1962, 95 municipalities in four states were discharging wastewater to the Connecticut River basin; of these only 41 provided primary treatment and 26 provided secondary treatment. Industrial discharges of untreated wastes from paper, chemical, metal plating, textile dyeing, and other industries also contributed to a serious health and environmental problem. A number of initiatives, including the Connecticut Clean Water Act of 1967, the Federal Water Pollution Control Act of 1972, and the Clean Air Act of 1970 (including the 1990 amendments) have led to improvements in the water quality of the Connecticut River basin during the past 30 years. Trend analysis of selected U.S. Geological Survey water-quality monitoring data collected in Connecticut from 1968-98 was conducted using the nonparametric seasonal Kendall test. Selected sites were further analyzed as part of a later investigation using a time-series model with a periodic autoregressive moving average (PARMA) filter. Downward trends that were detected included total phosphorus, total nitrogen, indicator bacteria, and sulfate concentrations; upward trends that were detected included pH, dissolved oxygen, and chloride concentrations. However, despite improvements in water quality in the Connecticut River, significant challenges remain. These include, but are not limited to, the need for: reduction in non-point source pollutants due to increasing urbanization, further reductions in nitrogen loads to improve dissolved oxygen concentrations in Long Island Sound, further reductions in bacteria concentrations to attain Connecticut Class B water-quality criteria, and separation of combined sewers to prevent overflow of untreated sewage