Source Water Assessment and Protection

The Source Water Protection Program aims to gather valuable information about a community's source of drinking water. Source water assessment information should tell residents exactly where their water supply comes from and what conditions and/or practices may pose threats to its quality.

DEQ conducts Source Water Assessments (also known as Source Water Delineation and Assessment Reports) that analyze existing and potential threats to the drinking water of public water supplies.

Each Source Water Assessment includes four major elements:
1) Delineating (or mapping) to identify where a public water system’s water comes from;
2) Conducting an inventory of potential contamination sources in the areas that contribute water to a public water system;
3) Determining how susceptible the water supply is to the potential contamination sources; and
4) Making the Source Water Assessments available to the public.


1. Identify the Source(s) of Water used by Public Water Systems

Source water protection areas are delineated for ground water and surface water sources. This technical process considers characteristics of the aquifer or watershed and the public water system intake. It then identifies the land area that contributes recharge to the hydrologic or hydrogeologic system above or upgradient from the public water system well or intake structure. These protection areas are part of a source water delineation and assessment report (SWDAR) and are shown graphically on a map. Check out examples of completed reports on the Internet

2. Identify and Inventory Potential Contaminant Sources

Potential contaminant sources within the source water protection area are identified and described in the assessment report. Regulated contaminants of concern in Montana include nitrate, microbial contaminants, and certain fuels, solvents, herbicides, pesticides, and metals. Potential contaminants sources include septic systems, animal feeding operations, underground storage tanks, floor drains and sumps, and certain land use activities.

3. Assess the Susceptibility of Public Water Systems to Potential Contaminant Sources

A susceptibility assessment consists of evaluating the setting of the well or intake and the relative hazard posed by potential contaminant sources. A determination of relative susceptibility for each significant potential contaminant source identified within the source water protection area will be in the assessment report.

4. Make Results of the Delineation and Assessment Available to the Public

Source water assessments must be made available to the public; this is accomplished by completing a technical report that addresses items one through three above. Various media are used to distribute the reports including the Source Water Assessment Program (SWAP) Internet site, state library, and excerpts in the consumer confidence reports.

Review Source Water Assessment Reports

Source Water Delineation and Assessment Form Instructions

Source Water Protection Delineation - PWS-6

Local water quality districts  are formed by county governments. Legislation describes district organization and specifies the authorities that can be exercised at the local level. The Montana Department of Environmental Quality provides support to local water quality district programs but does not have an active management role in their activities. Districts have been formed in Missoula, Lewis & Clark, Silver Bow, and Gallatin Counties. These groups serve as local government districts with a governing board of directors, and funding obtained from fees collected annually with county taxes, similar to funding mechanisms for other county districts.

Local Water Quality Districts

Water Protection Bureau 444-5546

Public Water Supply Bureau 444-4400