Date of Award
Master of Community Planning
John J. Kupa
Groundwater is an important drinking water resource in the United States, especially in rural areas, unconnected to larger public systems, where it provides 96% of the drinking water supply (Travis and Etnier, 1984) . Approximately 50% of all U. S. residents rely on groundwater as their source of drinking water, using 88 billion gallons a day (Patrick et al. 1987). Within the State of Rhode Island, 24% of the population depends on groundwater and 8% utilize private drinking wells (USGS, 1988). Groundwater withdrawals in Rhode Island average 37 million gallons per day and uses include public and private water supply, livestock and irrigation, and industrial uses (USGS 1986) .
A recent study of the Rhode Island water supply, conducted by the Arthur D. Little Company, has indicated that the state's increasing reliance on the Scituate Reservoir system may cause future supply problems, forcing water suppliers to look to groundwater as a supplemental source. In most New England states, groundwater is a primary drinking water source.
Groundwater is generally available in good quality throughout the nation, although supplies are gradually becoming more threatened by human activity. The duration, type, and intensity of human activities will determine the degree of risk that is posed to both ground water quality and quantity. As further development takes place, additional pollutants are introduced into the groundwater, significantly impacting water quality. Rhode Island's twenty-one major groundwater aquifers are extremely susceptible to contamination due to high aquifer permeability and minimal depth (usually less than 20 feet) to the water table (USGS, 1986) . Since 1975, the water from 9 public supply wells and 250 private wells has become unsuitable for human use due to contamination by hazardous chemicals (USGS, 1986) .
Groundwater contamination occurs as a result of three main mechanisms: by natural processes, by man's waste disposal practices (sanitary, industrial, solid, and hazardous wastes), and by spill (and illegal dumping), leaks, and agricultural activities and other sources unrelated to disposal. Non-point sources of groundwater pollution include nutrient loading from septic systems, erosion and sedimentation from construction sites, stormwater runoff carrying nutrients, heavy metals and hydrocarbons, road de-icing practices with heavy salt concentrations, and the use of pesticides and fertilizers. Past land uses may yet cause groundwater contamination. Many of the known 16,000 hazardous waste sites nationwide that are now closed will eventually leach contaminants into the ground, as will the 2 million underground storage tanks containing petroleum and chemical products (Page, 1987).
It is difficult to assess the overall threat to groundwater from a particular land use. The actual threat presented by a land use depends upon several factors including; (1) the type and quantity of chemicals used or wastes generated, (2) storage and disposal methods, (3) soils and aquifer characteristics of the site, (4) distance from the contamination source to the wellfield, and (5) the attenuation of the pollutant in the soils and ground water. These factors all contribute to the complexity of adequately protecting ground water quality.
Gardella, Mark C. and Ribb, Richard C., "A WELLHEAD PROTECTION PROGRAM NORTH SMITHFIELD, RI" (1991). Open Access Master's Theses. Paper 556.