The findings from Cycle I water-quality sampling and analysis in the CONN Study unit are summarized in publications listed in: http://ct.water.usgs.gov/nawqa/pubs.htm. (Publications Link)

CONN NAWQA Timeline

The CONN study unit extends over an area of about 15,750 square miles from the Canadian border to Long Island Sound (map 1). The study unit includes parts of six States--eastern Vermont, western New Hampshire, west-central Massachusetts, nearly all of Connecticut, and small parts of New York and Rhode Island. Although it occupies less than one-half of 1 percent of the total area of the Nation, about 4.5 million people, or about 2 percent of the Nation's population, inhabit the study unit. The study unit is characterized by diverse population density (map 2) ranging from the sparsely populated, rural agrarian and wilderness areas of northern Vermont and New Hampshire to the densely populated urban areas of southwestern Connecticut and the south-central part of the Connecticut River valley. Approximately 80 percent of the study unit is forested undeveloped land, about 12 percent is agricultural, and 8 percent is urban development (map 3). The principal economy in the northern part of the study unit is based on agriculture, primarily dairy farming, forestry, and seasonal recreation. In the southern part of the study unit, the economy is based predominantly on manufacturing, financial services, and service industries. The principal cities of Hartford, Springfield, Bridgeport, and New Haven are all located in the southern part of the study unit.

The study unit is located entirely within the New England physiographic province, a plateau-like upland that rises gradually from the sea but includes numerous mountain ranges and individual peaks. Altitudes range from sea level in coastal Connecticut to 6,288 feet above sea level at the peak of Mount Washington in the White Mountains of New Hampshire. Most of the area is within the New England Upland section of the province where the topography is characterized by rolling hills and low, rounded mountains interrupted by numerous, generally narrow valleys. The Connecticut River valley forms a broad lowland that extends from a short distance south of the Vermont-New Hampshire-Massachusetts border to within 20 miles of Long Island Sound. The relief is higher in the northern part of the study unit where the Green Mountains of Vermont and the White Mountains of New Hampshire commonly reach altitudes between 2,000 and 4,000 feet above sea level.

The climate differs considerably within the study unit, but is generally temperate and humid. Average annual temperature ranges from less than 40 degrees Fahrenheit in the northern mountainous areas to about 50 degrees Fahrenheit in southwestern coastal Connecticut. Average annual precipitation in the study unit is 43 inches, but ranges locally from about 34 inches at places in the northern end of the Connecticut River valley to more than 65 inches in some mountainous regions. Annual precipitation, however, commonly fluctuates as much as 20 inches from these averages.

The Connecticut River is the principal river, extending 383 miles from its source in the Connecticut Lakes of northern New Hampshire to its outlet at Long Island Sound. The river drains 11,260 square miles, or about 72 percent of the study unit. Flow of the Connecticut River near the Connecticut-Massachusetts border averages about 10,600 million gallons per day. Other major streams include the Housatonic and Thames Rivers, which together drain 3,420 square miles or about 20 percent of the study unit. Numerous smaller streams and rivers that flow directly into Long Island Sound collectively drain 1,070 square miles in coastal parts of the study unit.

Two of the Nation's 16 principal aquifers underlie the study unit--unconsolidated glacial sand and gravel (stratified-drift) aquifers (map 4) and fractured crystalline bedrock aquifers (map 5). Stratified-drift aquifers are generally the most productive sources of ground water in the study unit, but they are not evenly distributed. The unconsolidated, stratified-drift aquifers store and transmit water through interconnected pores between individual grains of sediment. Differences in the thickness, extent, and permeability of the stratified-drift aquifers, and the proximity and size of surface-water bodies that are sources of recharge, significantly influence the availability of water.

Fractured bedrock aquifers underlie the entire study unit and are an important source of water for self-supplied domestic, commercial, and industrial users. Bedrock aquifers primarily store and transmit water through intersecting fractures in consolidated rock. Well yields depend on the number, size, and degree of interconnection of water-bearing fractures. Relatively large yields of wells that tap bedrock aquifers in some places in the study unit have been associated with major fault zones and with areas where the bedrock is overlain by saturated stratified drift.

Water-Quality Issues

Major water-quality issues of concern in the CONN Study Unit include effects from urbanization, atmospheric deposition, agriculture, forestry, and recreational development on the region's water resources. Urbanization has been most extensive in the southern part of the study unit, while agriculture, forestry, and recreation are the main activities in the northern part of the study unit. Urban areas are scattered throughout the study unit but the largest areas are clustered along the shoreline of Long Island Sound and in the lower Connecticut River valley.

The findings from Cycle I water-quality sampling and analysis in the CONN study unit were reported in USGS Circular 1155. They include: (1) Accumulations of toxic contaminants exist in both fish and sediments. Trace element and organic contaminants were found in highest concentrations in southern parts of the study area. (2) Nutrient concentrations remain a concern for surface-water quality. Although phosphorus concentrations in surface water have declined and overall improvement continues, nutrient loadings to streams and rivers in the CONN study unit and to Long Island Sound from atmospheric deposition, agricultural ertilizer and manure applications, urban nonpoint runoff, and urban waste-water-treatment plants continue to degrade water quality. (3) Pesticides were frequently detected in streams. Most streams sampled had some pesticide detections although concentrations did not exceed Maximum Contaminant Levels (MCLs). Streams in urban basins had more frequent detections of insecticides than did streams in agricultural basins. (4) Several classes of contaminants were detected in ground water. Pesticides, volatile organic compounds (VOCs), and nitrate were commonly detected at levels exceeding background and some concentrations exceeded MCLs. Methyl tert-butyl ehter (MTBE), a gasoline additive, and chloroform were the most commonly detected VOCs. (5) Radon was commonly detected in ground water in the study area at levels exceeding a proposed limit.

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