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

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28 4 Water Supply Sources Introduction The Twin Cities metropolitan area is fortunate to have relatively abundant water resources. The Mississippi River and the region's prolific aquifers provide residents with reliable water supplies, while its rivers and lakes serve commerce, support wildlife, and offer people a variety of recreational opportunities. No single source supplies the region's water demand, as described in Chapter 3. Instead, a combination of sources provides the Twin Cities metropolitan area with water to meet its current and growing needs: groundwater, surface water, stormwater, and reclaimed wastewater. This chapter describes the major water supply sources available to the region. The chapter also summarizes challenges and opportunities identified by the region's water supply managers and decision -makers. Plans to use these sources for current and future demand need to consider the issues presented in Chapter 5. Supplementing existing sources with additional approaches This plan recognizes that, across most of the metropolitan area, many communities rely on only one source of water. Local governments, businesses, public institutions, and private households have together invested many millions of dollars in the existing water supply infrastructure. The Metropolitan Council recognizes the value of these past investments and supports plans that leverage these existing community investments in infrastructure within the regional and local sustainable limits of water sources. Where demand exceeds the sustainable limits of current sources, water conservation and a combination of other sources may be used to reduce demand for groundwater or augment groundwater to support demand. Each community may consider which combination of water supply approaches work best for them. Some strategies, like water conservation, can begin immediately and eliminate the need for or buy time to consider additional options. Other strategies, like expanding surface water infrastructure, take longer to implement but can alleviate pressure on groundwater systems in areas with irreducible demand for potable water. Much like investing, a deliberate collection of water supply sources, programs, and infrastructure will provide us with the best short and long-term water supply options. In some areas, expansion of surface water use to supply potable water has the dual benefit of reducing groundwater withdrawals and improving the suitability of reclaimed water for industrial and irrigation uses, by reducing the use of water softeners and resulting chloride concentrations in wastewater. In other areas, addition of groundwater wells can provide a backup source of water to communities relying solely on surface water during extreme drought or contamination events. Stormwater can be collected as precipitation runs off from impermeable surfaces, such as rooftops, and stored for future use. Like groundwater wells, stormwater reuse projects can be installed as development occurs, providing a local water source as local growth occurs. Stormwater is used as a relatively minor water supply throughout the region; it is most commonly used for irrigating turf areas. While still a minor source serving non -potable needs, this source is expected to grow. Urban non -crop irrigators, such as golf courses, landscaping and athletic fields, may be especially well suited for using stormwater since they represent a significant water demand and water quality requirements are less of a concern. Based on preliminary work done in Dakota County, it appears WATER SUPPLY MASTER PLAN- Draft June 2015