MICHIGAN'S SOURCE-WATER ASSESSMENT PROGRAM – SURFACE-WATER ASSESSMENTS LEADING TO PROTECTION INITIATIVES

Abstract

Michigan has 67 water supplies that use surface-water sources. These supplies provide drinking water to over 60 percent of the State’s population, or about 6 million people. The U.S. Geological Survey and Michigan Department of Environmental Quality are cooperating on a project to assess the risk to community surface-water sources from potential contaminant sources. Section 1453a of Public Law 104-182, reauthorization of the Safe Drinking Water Act of 1996, requires Federal guidance and defines State requirements for a source-water assessment program. The U.S. Environmental Protection Agency published the State Source-water Assessment and Protection Programs Guidance in August 1997 to assist States in developing an acceptable source-water assessment program. By statute, a State’s source-water assessment program must complete assessments for all sources of public drinking water that (1) define source-water areas, (2) list potential contaminant sites and contaminants of concern, and (3) determine raw water susceptibility to contamination. States then must work with public-water suppliers to inform the public of these results. Results of the assessments are to be presented in reports for each surface-water facility. Inland lake and river intake assessments (8 supplies in Michigan) are watershed based. The assessment process for these source waters includes reviewing water-quality monitoring records and identifying potential contaminant sources. Great Lakes and Great Lakes Connecting Channels intake assessments (59 supplies) follow the “Assessment Protocol for Great Lakes Sources” developed by Great Lakes States in U.S. Environmental Protection Agency Region 5. Assessments include local data on land-use, contamination sources (sewer outfalls, leaking storage tanks, air deposition, etc.), information from local water-plant personnel (intake construction and location, influent quality, effects of weather, lake currents, etc.), and centralized State and Federal data resources (census data, permitted discharges). A pilot assessment completed for the Alpena, Michigan, water supply identified potential effects to the intake from a nearby river, atmospheric conditions, and two storm-sewer outfalls. The preliminary Alpena assessment was received favorably by the community, and provided the basis of a source-water protection program for the community. In addition to methods established for the assessment of Great Lakes supplies, assessments of supplies that use Great Lakes Connecting Channels as their source (14 supplies) will be included in a two-dimensional, hydrodynamic flow model of the St. Clair River–Lake St. Clair–Detroit River system. The flow model will define source-water areas, track contaminant source-waterquality concerns, and assist in developing contingency plans. A partnership established among the Michigan Department of Environmental Quality, U.S. Geological Survey, U.S. Environmental Protection Agency, U.S. Army Corps of Engineers, and the Detroit Water and