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<br />Marian Meadows Rezone and Subdivision Final Environmental Impact Statement 1-29 <br />Groundwater Resources <br />Water withdrawal for domestic use would reduce groundwater resources in the area. It is likely that the <br />major effect would be the cumulative effect of reduction in overall resources available in the watershed <br />for other beneficial uses, including agriculture, fish habitat, and recreation. The use of sewage treatment <br />facilities that return domestic water to groundwater can reduce the loss of groundwater resources and <br />reduce watershed-wide effects. This is about equally effective whether water returned to groundwater is <br />from a sewage treatment plant or septic tanks. The major potential loss of groundwater to the overall <br />watershed is use for irrigation that results in a substantial loss due to evaporation. This loss is especially <br />significant for groundwater because this resource is protected from evaporation and often is the source of <br />low summer flows in surface waters in the Yakima Valley. <br />The major risk to groundwater quality and domestic supply is the potential for failure of the sewage <br />treatment facility to meet discharge standards. Discharge of untreated wastewater would cause the <br />average nitrate concentration in groundwater to exceed drinking water standards in downgradient wells. <br />Vegetation and Wetlands <br />All alternatives would remove much of the existing forest cover on the flatter western portion of the site. <br />Alternatives 1, 3A, 3B, 3D, and 4 would remove varying proportions of the forest cover on the steeper <br />eastern portion of the site. <br />Alternative 1 would involve residential development in the vicinity of existing wetlands in the bench <br />area of the eastern portion of the site. Direct impacts would depend on the size of buffers included in the <br />proposal. Regardless of the preservation of wetlands or the size of buffers, some change in the hydrologic <br />conditions that support the wetlands can be expected either from diverting water that currently infiltrates <br />into the ground and recharges the wetlands, or through additional discharge of stormwater into <br />watercourses and to the wetland. In either case, the natural hydroperiod of the wetlands would change <br />and have a ripple effect on functions. <br />Alternatives 2, 3C, and 5 would have much less impact on wetlands in the eastern portion of the site <br />because the area would remain undeveloped and subject to disturbance only on the cycle of one a decade <br />or less often for forest management practices. Some disturbance could be expected from recreational <br />activities, but at a much lower intensity than from residential use. <br />Alternatives 3A, 3B, and 3D would involve residential development in the vicinity of existing wetlands <br />in the bench area of the eastern portion of the site. Direct impacts would be somewhat less than <br />Alternative 1 because of the lower intensity of use and would also depend on the size of buffers included <br />in the proposal. <br />Alternative 4 would have similar impacts as Alternative 1 on wetlands because development is clustered <br />in the flatter bench area where the wetlands are present.