Agenda - Council - 07/28/2015 - Laserfiche WebLink

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• Residential per capita water demand is greater than 75 gallons per person per day, which is the goal recommended by the Minnesota Department of Natural Resources • The trend in total per capita water use is not decreasing, which is a goal recommended by the Minnesota Department of Natural Resources • A ratio of maximum demand day to an average demand day exceeds 2.6, which is the goal recommended by the Minnesota Department of Natural Resources The challenges of water demand management vary throughout the region, primarily driven by differences in level of development. For example, individual public water suppliers vary in the amount of unaccounted water region based on different metering systems or the age of the infrastructure. New development may be associated with higher per capita use and peak summer water use as new vegetation is established. Older communities with aging infrastructure may have higher amounts of unaccounted for water use. Water use conflicts and well interference There are tens of thousands of wells in the region, supplying diverse users. Where water users compete, conflicts must be resolved - often a costly process. Water use conflict is defined in Minnesota Rules (part 6115.0740) as a condition where the available supply of water in a given area is limited by a competing demand that exceeds the reasonably available waters. However, even where there is adequate water for a proposed project, a well interference can occur if that project interferes with the ability to withdraw water from a public water supply well or private domestic well. The following are specific indicators of increased risk of well interference: • Documented well interference problems • High volume water users in proximity to residential wells Because private wells are pervasive in the metro area, there is a potential for well interference for all water users. Complaints about well interferences are reported to the Minnesota Department of Natural Resources (DNR), which then works to resolve the issue through the process set forth in Minnesota Rules (part 6115.0730). Aquifer water levels Aquifer levels are useful for providing information about groundwater flow directions, relationships between groundwater and surface water systems, and water levels near wells, so the issue of aquifer water levels is closely related to issues like water quality, surface water -groundwater relationships, and well interference. Monitoring networks provide information about current and past conditions, and modeling is a valuable tool to anticipate potential future conditions. In several parts of the metropolitan area, historical DNR groundwater level monitoring data suggest long-term declines. Groundwater levels in other parts of the metro area have remained relatively constant over time. One example of long-term decline can be found in Orono, Minnesota where groundwater -level monitoring has documented declines of one foot per year in the Prairie du Chien - Jordan aquifer. However, water levels in the St. Peter aquifer in Roseville have generally trended upward since the early 1990s. While some parts of the metro area have not yet experienced groundwater declines, existing data show that aquifer decline is an issue that needs to be addressed in parts of our region (figure 20). Aquifer decline issues vary throughout the region, primarily driven by differences in aquifer properties and level of development. The Department of Natural Resources evaluates water level impacts on confined aquifers using the definition of safe yield found in Minnesota Rules (6115.0670). Those rules define safe yield as the amount of groundwater that can be withdrawn without degrading water quality or causing a continual WATER SUPPLY MASTER PLAN- Draft June 2015 43