ERMUSR 4-11-2023 Special Meeting

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Forward This document presents an amended, comprehensive wellhead protection plan for Elk River Municipal Utilities (ERMU) that will help provide for an adequate and safe drinking water supply for community residents. ERMU has made good progress in implementing the current wellhead protection (WHP) plan and continues in efforts to protect the City of Elk River's source water. This amendment reflects relatively minor amendments to the boundaries of the emergency response areas, wellhead protection areas and the drinking water supply management area (DWSMA) since the previous WHP plan. The moderately vulnerable area within the DWSMA has been refined. The vulnerability status of Well 93 changed from nonvulnerable to vulnerable due to results of recent water sampling. This amended WHP plan includes addressing important issues of expected growth in population and associated increase demands on the sole -source aquifer used to supply potable water for the City of Elk River and many other public and private well owners in the region. The City and ERMU will continue to work with citizens and local and state partners in implementation of the WHP plan. MDH wellhead protection rules require a review and assessment of various data elements as determined by DWSMA vulnerability that must be completed for the DWSMA. This process must address existing and historical aspects of the 1) physical environment, 2) land uses, 3) water quantity and 4) water quality. The data assessment process conducted by the ERMU wellhead protection team supports both the delineation and vulnerability reports (Part 1) and assists in the identification of potential impacts the data elements may have on the source water and how the water supplier can address potential impacts (Part 2). Appendix A contains detailed assessments of all applicable data elements for the DWSMA. Eight wells contribute source water to the ERMU system. Each well has undergone an extensive groundwater modeling process as part of wellhead protection planning. The modeling results are presented in the Part I report. The Part I report is located in Appendix B which contains the 1) delineation of the wellhead protection area, 2) delineation of the DWSMA, and 3) the assessments of well and drinking water supply management area vulnerability. The Part I report was approved by the Minnesota Department of Health (MDH) before the second part of the plan was prepared. The remainder of the wellhead protection plan is referred to as `Part 2' and contains procedures followed for conducting an potential contaminant source inventory (PCSI) and the development of goals, objectives and measures that ERMU will take to offset the risk that potential contamination sources present to the public water supply system. The identification of potential contaminant sources within the DWSMA is a fundamental element of wellhead protection. A PCSI is needed to assign meaningful priorities to management measures and to effectively monitor the effectiveness of implementation of the WHP plan. This is an ongoing process that entails inventorying present and past land uses and periodically updating the PCSI as land uses change within the DWSMA. The extent of potential contaminant inventory conducted within a DWSMA is determined by the vulnerability of the public water supply wells and the DWSMA. The ERMU wellhead protection team has conducted an inventory of potential contaminant sources within the DWSMA which are discussed in Chapter 4 and shown on maps and tables in Appendix C. The wellhead protection team discussed and listed any expected changes to the physical environment, land use, surface and groundwater that may impact the aquifer serving the public water supply wells in the DWSMA. Chapter 5 discusses this subject in greater detail to clarify expected changes and how those changes may impact the source water used by ERMU. A WHP plan must identify water use, land use issues, problems and opportunities related to the aquifer serving the public water supply wells, the well water and each DWSMA. The wellhead protection team utilizes this process to define the nature and magnitude of contaminant source management issues within each DWSMA. The identification of issues, problems and opportunities that may exist in the DWSMA enables ERMU to 1) take advantage of opportunities that may be available to make effective use of existing resources, 2) set priorities for management of contaminants listed, and 3) request support for implementing specific management strategies. 9