The Quinnipiac River watershed is comprised of 9 sub-basins. Map sets for each sub-basin can be accessed by clicking on the name of each sub-basin.
The Quinnipiac River watershed has an area of 166 square miles (sq mi) and the total length of watercourses (brooks, streams, rivers) is 522 miles. That is 3.1 miles of watercourse per sq mi of watershed, which helps to explain the connection between water quality and environmental conditions in the terrestrial portion of the watershed. Land use in the watershed is very mixed. Using general categories, approximately 73 sq mi is vegetated (this includes forests and also very low density residential areas with large amount of vegetation), 52 sq. mi. is urban (medium to high density residential, commercial, impervious), 36 sq mi is agricultural and there are about 5 sq mi of water bodies (lakes, ponds).
About 200,000 people live in the watershed. There are 6 water pollution control facilities (5 public, 1 private). Approximately 42.8 sq mi of the watershed has sewers, representing 83% of the urban area. Based on data collected in 1996, there are 3,166 sites in the watershed which have had some type of environmental regulatory activity since about 1980 (this includes a variety of situations and not all are active). That is about 19 sites per sq mi of watershed.
Despite extensive impacts to the watercourses and modifications in several portions of the watershed, the Quinnipiac River, its tributaries and the surrounding landscape provide habitat for many species of plants and animals and constitute an important natural and economic resource in the state. Information proving details on these topics are provided in this atlas and via links to other sites.