Source Water Protection

Montana’s Source Water Protection Program was created in 1999 in response to the 1996 amendments to the Safe Drinking Water Act, which required states to assess drinking water sources and help communities protect them from pollution. DEQ provides guidance through  Circular PWS-6 , which outlines the required elements of a source water delineation and assessment report.

What is source water?

Source water refers to sources of water (such as rivers, streams, lakes, reservoirs, springs, and groundwater) that provide water to public drinking water supplies and private wells. Public drinking water can come from two sources: surface water (streams, rivers or lakes) and groundwater (wells or springs).

Why protect source water?

Protecting source water reduces risks to public health by preventing contamination before it enters the drinking water system, helping utilities lower treatment costs and avoid more complex solutions. It also safeguards water quality for wildlife, recreation, and long-term water supply reliability, making source protection a more efficient and cost-effective approach than treating polluted water or developing new supplies.

Step 1- Delineate the source water protection area (SWPA)

A source water protection plan includes a delineated area that shows the area to be assessed and protected based on where the public water system draws drinking water supplies.

Step 2- Inventory known and potential sources of contamination

A contaminant source inventory lists all documented and potential contaminant sources or activities of concern within the SWPA that may pose a threat to drinking water supplies.

Step 3- Determine the susceptibility of the public water system to contaminant sources or activities within the SWPA

Determining the susceptibility of the public water system to threats included on the contaminant source inventory list is an important step for connecting the nature and severity of the threat to the likelihood of the threat contaminating source water.

Step 4- Engage the public about threats identifies in the assessment

Effective source water protection programs ensure that the public has the information necessary to act to prevent contamination. Early involvement in the planning process helps build consensus on the need for action, leading to more comprehensive source water protection.

Step 5- Develop an action plan to identify and prioritize specific implementation activities

Communities can use the information gathered from the source water assessment process to develop  action plans identifying long-term management strategies for preventing contamination of sources of drinking water.

Step 6- Protect source of drinking water by implementing protective actions

Communities use many different source water protection practices to prevent contamination of their drinking water supplies. These measures can be tailored to address each threat or an array of risks specific to each public water system.

Step 7- Evaluate and update action plan periodically

Plans should be evaluated and, if necessary, revised in response to new information, such as changes to the watershed or source water protection area or other factors that could affect the relevance and efficacy of the plan.

These are the steps recommended by the EPA for protection partners. More information can be found on the EPA source water protection page.

This mapping application is designed to show locations of current source water sites and facilities, existing source water regions, and potential contaminant sources that Montana DEQ uses in source water assessments. Users can find potential contaminant sources near their area of interest by using the tools found in this viewer. To learn how to use the mapping application, view the Montana Source Water Protection Viewer instructional video (03:25).