This general-interest report appraises the occurrence, source, flow, and quality of ground water in Rhode Island. Ground water, withdrawn from all major geologic units in Rhode Island, provided drinking water for about one-fourth of the State's population in 1985.Ground water, mostly unconfined, is found in unconsolidated glacial till and stratified drift and in the underlying fractured bedrock. Thick deposits of stratified sand and gravel are the most productive aquifers in the State for public supply. Most private wells tap bedrock aquifers.Ground water flows from upland recharge areas toward valley discharge areas. Most of the land surface is a recharge area. Large-capacity wells, located in permeable sediments near streams, commonly induce surface water to flow from streams into aquifers.Concentrations of dissolved solids in ground water are generally less than 200 milligrams per liter, as compared to the National Secondary Drinking-Water Regulation of 500 milligrams per liter. Natural contaminants include iron, manganese, and radon. Withdrawals in coastal areas have caused saltwater intrusion.Waste-disposal sites, industrial spills, leaking underground storage tanks, road salt, agricultural chemicals, and septic systems have contaminated ground water at some locations with metals, nitrate, bacteria, radionuclides, excessive concentrations of common ions, and more than 50 synthetic organic chemicals and petroleum products. Contamination by volatile organic compounds has been the major cause of public-well closings.The rural Pawcatuck River basin contains nine high-yield stratifieddrift aquifers. Southeastern Rhode Island, covered by clayey till, has no major aquifers. Stratified-drift aquifers in urbanized northeastern Rhode Island have a large potential yield but many water-quality problems. Rural western areas depend on ground water.
Purpose and Scope of the ReportThis report provides Rhode Island's citizens with a broad overview of the State's ground-water resources and ground-water-contamination problems. The intended audience includes interested citizens, teachers, State and local government boards and agencies, and private organizations involved in water-resources issues.The following questions were posed in developing the report: * What is the importance of ground water in Rhode Island? * What is ground water? * Where does it come from? * Where does it go? * How does ground water become contaminated? * Where are the major ground-water resources and contamination problems in Rhode Island?
