Source Water Assessments:
Fact Sheet for Public Water Supply Owners and Operators


Download a print version of this Web page, including a source water assessment example on pages 3 and 4 of the document:
Source Water Assessments: Fact Sheet for Public Water Supply Owners and Operators (PDF: 459KB/4 pages)

Source Water Assessments were sent to all public water systems in 2003

Between March and May 2003, the MDH Source Water Protection Unit sent out “Source Water Assessments” to all public water systems in Minnesota. This fact sheet helps explain Source Water Assessments and answers some basic questions you may have regarding the assessments. Note that this fact sheet is focused primarily on ground water systems – the process for surface water systems is different (see discussion below).

What is a Source Water Assessment?

A Source Water Assessment is a document – produced by MDH, provided to the public water system, and made available to the public – which summarizes a variety of information regarding the water sources used by a public water system. Specifically, the assessment includes the following:

  • A description of the drinking water source(s) used by the water system (i.e. your well or wells) and the area that contributes water to the source(s). This will include a map showing the location of your water source(s).
  • A determination of the “susceptibility” of your drinking water source to contamination. Susceptibility describes how likely it is that a water source may become contaminated. For wells, susceptibility is based on well construction, the type of aquifer that supplies the well(s), and previous water sampling results.
  • Drinking water contaminants of concern to anyone using the water source. For wells, this will be based on any detection of regulated contaminants during previous water sampling.

Along with the text portion of the assessment, a map will be generated showing the Inner Wellhead Management Zone for the well(s) or a Drinking Water Supply Management Area (DWSMA), if one has been approved. Note that only systems that have formally entered the wellhead protection planning process will have an approved DWSMA.

Why were Source Water Assessments created?

Under the 1996 amendments to the Safe Drinking Water Act, MDH was required to produce Source Water Assessments for all Minnesota’s public water systems by May 30, 2003 – and make these assessments available to the public. The idea behind assessments is the creation of document that can provide a concise summary of available information regarding a water system’s source(s). This information is then provided to both the public water system owner/operator and the public at large.

How are Source Water Assessments created?

Source Water Assessments are generated by MDH using existing data from water sampling, water system surveys, and well records. One Source Water Assessment is produced for each public water system – even if the system has multiple wells.

How and when were Source Water Assessments sent out to public water systems?

Distribution took place between March and May 2003. Assessment information was subsequently made available to the public on the Source Water Assessments of Public Water Systems Web page.

How will Soure Water Assessments be updated?

Assessments will be updated as soon as new information (such as well construction data) is added to the databases that are used to generate the assessments. The assessments shown on the website will then be updated to reflect these changes.

What exactly is on the website?

Information will be posted on the website as follows:

  • Community and Nontransient Noncommunity Public Water Systems: Only the text portion of the assessment will appear on the website until the system has an approved DWSMA – something that occurs once the system has entered the wellhead protection planning process. Once a DWSMA is approved, the assessment on the website will be updated to include a map of the DWSMA. However, due to security concerns, specific well locations will not be provided with the DWSMA maps.
  • Transient Noncommunity Public Water Systems: For transient systems, only the text portion of the assessment will appear on the website. There will not be a map of the IWMZ or a well location posted.

A Source Water Assessment is not a Wellhead Protection Plan

A Source Water Assessment and a Wellhead Protection Plan are two separate and distinct documents. However, the assessment can aid a water system in its wellhead protection process and provides an update of the system’s progress in source water protection. Keep in mind that the assessment is a document produced by MDH, while the wellhead protection plan is developed by the public water system and its wellhead protection planning team.

How is the process different for public water systems using surface water?

Due to the unique issues involved in creating assessments for surface water systems, and the limited number of surface water systems, source water assessments for water supplies using surface have been developed on a case-by-case basis, in close consultation with the water system.

Go to > top.

Updated Tuesday, 21-Jan-2014 11:37:47 CST