2015-02-11 CC Packet - Laserfiche WebLink

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Draft North & East Metro Groundwater Management Area Plan 3-7 Objective III. Groundwater use in the GWMA does not degrade water quality. Pumping groundwater does not directly degrade the quality of the water in the aquifer in most circumstances. However, some pumping can cause water levels in wells to fall below the top of an artesian aquifer(See Figure 3-1), resulting in conversion to a water-table condition. In some circumstances this can lead to changes in water chemistry and degradation of water quality. Compliance with safe yield for artesian aquifers prevents this situation from occurring as described under Objective 1. The effects of groundwater pumping on existing contamination must be considered when evaluating groundwater appropriation permits. Groundwater pumping can cause existing groundwater pollution to move or spread. Changes in groundwater levels and pressures can increase the movement of pollutants between aquifers or increase the spreading of pollutants within the same aquifer. In some cases, pollution containment wells are used to limit movement of contaminated groundwater into less or uncontaminated areas of the aquifers (Figure 2-10).The MPCA, in cooperation with the responsible parties, determines duration and volume of pumping to contain pollution plumes and limit the movement or spreading of groundwater contamination. Finally, water quality considerations in surface-water features must be incorporated into groundwater appropriation thresholds for surface-waters. Changes to the amount of groundwater flow into surface- water features can affect water quality items such as temperatures and oxygen levels in trout streams. Section 5 of the GWMA Plan provides a set of actions to meet Objective III. P56