ISDS 



RESOURCE CONTAMINATION: ISSUES OF CONCERN IN THE BAY 

 WATERSHED AND ELSEWHERE IN THE STATE OF RHODE ISLAND 



Data on the extent of existing ISDS contamination of water resources in ttie Bay 

 watershed generally is extremely poor. A DEM one-time sampling survey of private wells 

 near possible pollution sources was completed in September 1987, but concentrated on 

 zones surrounding hazardous waste sites. Of the 450 wells sampled, only three or four 

 were in areas of high ISDS concentration. Final results of the sampling program are not 

 yet available, but occurrence of organics due to ISDS contamination was reported to the 

 ISDS Task Force. Otherwise DEM groundwater sampling efforts are primarily limited to 

 response to hazard incidence, and reported incidents generally reflect contamination due to 

 hazardous waste sources, rather than ISDS concerns. 



DEM samples coastal waters for total and fecal colifonn in regulating shellfish bed 

 closures. Coliform limits are defined in state Water Quality Standards. The 1988 305(b) 

 Report identifies areas closed for all or part of the year, and known or suspected 

 contaminant sources. 



The Department of Health (DOH) samples conventional pollutant levels in public water 

 supply wells pursuant to the requirements of the Safe Drinking Water Act, and may 

 additionally sample reservoirs and private well supplies in response to complaints. Since 

 1970, fecal coliform concentrations have been used as the indicator of sewage 

 contamination in determining whether water is safe for consumption, shellfish harvesting, 

 and/or swimming. 



The Rhode Island Areawide Water Quality Management Plan, river basin plans prepared 

 for Bay sub-basins during the 1970's, and regional water resource management plans all 

 identified general areas of concern, based on extent of sewering, known soil limitations, 

 and development density. Shallow depth to water table, shallow soil depths to bedrock, 

 and limiting soil conditions were identified as having contributed to severe ISDS 

 contamination problems in many towns, notably North and South Kingstown, 

 Narragansett, East Greenwich, West Warwick, Tiverton, Bristol, Warren, the Aquidneck 

 Island communities, Jamestown, and several communities in the Blackstone and other 

 tributary river basins. These planning sources provide general gtiidance regarding potential 

 problem areas, but require updating to ensure reliability. 



Localized surveys have been conducted in response to evident resource degradation. In 

 the Narrow River watershed, for example, a survey of densely developed areas was 

 conducted by the Narrow River Task Force in 1986 to identify the status of ISDS 

 conditions in areas considered to have been developed beyond carrying capacity. The 

 survey revealed that between 1980 and 1985, existing systems within the three-town 

 watershed experienced a 65 percent failure rate. The towns obtained Coastal Community 

 Impact funds to contract for follow-on study of the severe ISDS problems in the 

 Middlebridge community in South Kingstown. That research revealed that the conversion 

 to public water due to health concerns had actually exacerbated the ISDS overflow problem 

 by raising the water table significantiy. 



Research conducted in the coastal ponds watersheds, which have soil characteristics 

 similar to that of the Bay's western shore, has directiy linked bacterial contamination and 

 nutrient enrichment in the ponds to ISDS contamination of groundwater. Although other 



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