Ground and surface water used for drinking water supplies are often vulnerable to contamination from land use practices (e.g., farming) and potential contaminant sources (e.g., 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.

In 1996, Congress amended the Safe Drinking Water Act to emphasize the protection of surface and ground water sources used for public drinking water. The amendments require that each state possessing primacy over its drinking water develop a source water assessment plan for public drinking water sources, conduct assessments on all public water systems, and make the assessments available to the public. The Idaho Source Water Assessment Plan was completed by the state in 1999, at which time it was also approved and recognized by the U.S. Environmental Protection Agency (EPA).

DEQ was successful in completing assessments on all recognized public water sources by May 2003, in accordance with the timetable set forth by the state and the EPA. The completed source water assessments summarize the likelihood of individual drinking water sources becoming contaminated (usually a short-term "contamination event") and serve as a foundation for public water systems to prepare drinking water protection plans and implement protection measures.

While wellhead protection and drinking water protection are similar concepts with similar goals, they are not the same thing. The Wellhead Protection Program was established under the 1986 amendments to the Safe Drinking Water Act, with the expressed goal of minimizing the likelihood of contamination to public water systems supplied by ground water. The Idaho Wellhead Protection Plan was recognized and approved by both the Idaho Legislature and the EPA, and laid the groundwork and provided guidance for developing individual public water system wellhead protection plans. Many communities throughout Idaho have subsequently pursued voluntary wellhead protection efforts under the guidance set forth within the state's plan. The voluntary Wellhead Protection Program did not address the issue of protecting surface sources of drinking water.

The 1996 amendments to the Safe Drinking Water Act set forth requirements that states assess all water (both ground water and surface water) from which public water systems draw (called "source water") to provide drinking water. Idaho's Source Water Assessment Program was tasked with the responsibility of fulfilling these requirements. Idaho's Drinking Water Protection Program grew as a natural extension of the Source Water Assessment Program as the focus of the program's efforts transitioned from assessment to protection. Drinking water protection is an expansion of wellhead protection, as it protects intakes from surface waters (lakes, reservoirs, and streams) that are used to supply public drinking water systems, as well as protecting ground water wells. Wellhead protection in Idaho is now part of the larger Drinking Water Protection Program.

Idaho's Source Water Assessment Plan has replaced its Wellhead Protection Plan as the guidance document used in the process of delineating source areas and conducting susceptibility analyses for public water sources. Developed by an advisory committee of Idaho citizens in conjunction with DEQ personnel, the Source Water Assessment Plan is dynamic in nature and stresses public comment and participation as key elements in the assessment process. To the maximum extent possible, the process incorporates the use of geographic information system (GIS) technology. Methods used for delineating source areas have been refined so as to define zones of contribution that are as realistic as can be scientifically determined.

A source water assessment report has been prepared for each public water system in Idaho (view the source water assessment for your water system). A source water assessment report includes information on the potential contaminant threats to specific public drinking water sources and provides a foundation to help communities protect their drinking water supplies through implementing drinking water protection activities. Each source water assessment report:

• Defines the zone of contribution, which is that portion of the watershed or subsurface area contributing water to the well or surface water intake (source area delineation)

• Identifies the significant potential sources of drinking water contamination in those areas (contaminant source inventory)

• Determines the likelihood that the water supply will become contaminated (susceptibility analysis)

Each assessment is summarized in a report that describes the above information and provides maps of the location of the public water system, the source area delineation, and the locations of potential contaminant sources. more

It is recommended that a community develop a written plan to document its drinking water protection activities and that it use the plan as an informational and educational tool for the public. A community can gain official recognition for its drinking water protection plan by pursuing state certification through DEQ. The certification covers a five-year period, after which re-certification may be pursued.

In addition to the obvious benefit of having a plan to protect drinking water, systems with certified drinking water protection plans are granted additional points when applying for DEQ-administered drinking water grants and loans. Additionally, the U.S. Department of Agriculture Rural Development Program requires a system to have a current certified drinking water protection plan in order to receive financial assistance within Idaho. The EPA also requires a certified drinking water protection plan in order for a community water system to receive federal funding for projects drawing water from any of Idaho's three sole source aquifers.

For a community to have its plan certified, the plan must address eight protection elements and be technically appropriate. The eight protection elements are:

• A description of the planning team participants' roles and responsibilities

• A delineation of the drinking water protection area

• An inventory of potential sources of contamination

• A summary of management tools and protection measures that will be pursued to manage potential sources of contamination

• A contingency plan

• A protection strategy for new wells or intakes

• A public participation and education component

• An implementation strategy

Many of the above plan components are addressed by the system's source water assessment report, which can be attached to or otherwise incorporated into a community's written plan.

DEQ's Source Water Protection Grants provide funding for projects to protect sources of public drinking water.  Projects can take either a local or regional approach. Local projects will concentrate on protection of a specific community public water supply system while regional protection activities will cover multiple systems and communities.

Types of projects that are eligible for funding include those that are associated with source water protection measures. Operations and maintenance of the system and water treatment are not eligible activities. Community involvement and education is a central theme in these grants, and projects will be expected to provide long-term benefits to drinking water quality, quantity, awareness, and/or security.

> Link to Source Water Protection Grant Application.  Due April 3, 2009.

Drinking Water in Idaho: Information for Public Water Systems

Determine which type of public water system you operate and find information and resources specific to your industry.

Idaho Source Water Assessment Plan
(DEQ Publication, October 1999: pdf 2.4 mb, 200 pages)

Describes how source water assessments are conducted in Idaho.

Idaho Wellhead Protection Plan (Entire Report)

(DEQ Publication, February 1997: pdf 11.2 mb, 195 pages)

Because of the large size of this document, it has also been divided into sections for quicker downloading.  Click here to access the divided document.

Protecting Drinking Water Sources in Idaho: A Guidance for Public Water Systems

(DEQ Publication, August 2000, Revised April 2007: pdf 483 kb, 66 pages)
Provides guidance to parties interested in protecting drinking water sources in Idaho.