About Source Water

Source Water in Idaho?

Source water is the untreated ground water (aquifers and springs) and surface waters (rivers, streams, and lakes) used to supply drinking water for private, domestic wells and public water systems. Groundwater supplies approximately 95% of Idahoans drinking water; surface water supplies the remaining 5%. Both groundwater and surface water used for drinking water supplies are vulnerable to contamination from land-use practices (such as farming) and potential contaminant sources (such as gas stations) within the vicinity of drinking water wells and intakes. However, steps can be taken to minimize this vulnerability and help keep public drinking water free from contaminants. 

Source Water Assessments

A source water assessment provides information on the potential contaminant threats to public drinking water sources. As required by the Safe Drinking Water Act, assessments of all recognized public water sources in Idaho have been completed and summarized in reports that define the zone of contribution, identify the significant potential sources of contamination, and determine the likelihood that the water supply will become contaminated. Local communities can use the assessment to create a broader source water protection program to address current problems and prevent future threats to the quality of their drinking water supplies.

Learn more about source water assessments and access the report on your water system

Source Water Protection

The best method of safeguarding drinking water is to prevent source water contamination. Preventing contaminants from entering a public water system supply benefits the community by minimizing the problems that can occur from contaminants in the water supply, such as increased health risks to the public, expanded drinking water monitoring requirements, additional water treatment requirements, and expensive environmental clean-up activities.

Public water systems, local governments, and the public can implement source water protection measures to protect drinking water sources. Source water protection may include voluntary efforts like pollution prevention, education and outreach, or implementation of best management practices or it may include regulatory measures such as creating an overlay district or zoning ordinance that restricts certain contaminants or high-risk activities near a drinking water source.

DEQ’s online Source Water Protection Planning Tool can assist public water systems in developing a source water protection plan and contingency plan for their water system. The tool gathers information from existing databases, as well as input from user entry to create a planning document. To start a plan for your water system, log in or register to create a new account