Agenda - Public Works Committee - 10/19/2021

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Northwest Metro Aquifers March 12, 2020 Page 2 The geologic maps (Figures 2 and 3) indicate that the Tunnel City—Wonewoc is present in most of the study area,with the exception of bedrock valleys in Ramsey and Rogers. This report assumes that all of the new wells will be in the Tunnel City—Wonewoc aquifer. Mt. Simon-Hinckley Aquifer The Mount Simon-Hinckley Aquifer is generally described as a high to moderate yield aquifer. New high capacity wells are generally not permitted by the Minnesota Department of Natural Resources as use has been restricted by Minnesota Law, therefore it is not discussed in this report in greater detail. Regional Groundwater Supply In 2016, the Metropolitan Council along with the support of HDR completed a study on the groundwater supply within the Northwest Metro regional area (Regional Water Supply, Enhanced Groundwater Recharge, and Stormwater Capture and Reuse Study(Northwest Metro Study Area) Report, December 2016). The study was one of several studies to support an update to the Twin Cities Metropolitan Area Master Water Supply Plan (Minn. Stat., Sec. 473.1565)and other activities identified by the 2005 Minnesota Legislature to address water supply needs of the seven-county metro area. As part of these activities, the Metropolitan Council modeled the existing source water aquifers to evaluate current and future drawdown of the aquifers and discussed the potential for using alternative water sources or increasing water recharge to the source water aquifers. The 2016 study concluded that the existing source water aquifers are expected to see an increase in drawdown at existing municipal well sites under the predicted 2040 water demand. Areas within the Northwest Metro area could see drawdown in their bedrock aquifers between 10-40 feet. To compensate for the excessive drawdown, the report discusses the use of alternative water supplies such as surface water, stormwater reuse, and the potential for enhanced groundwater recharge.