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downstream could adversely affect anadromous spawning habitat and irrigation facilities. <br /> These impacts are considered potentially significant. <br /> Drainage and Runoff <br /> There would be no measurable change in the quantity of runoff as a result of the <br /> proposed project. During the gravel extraction phase of the project water is likely to <br /> become impounded in the open pits since the site is poorly drained. This could create a <br /> safety problem for operation of heavy equipment in the quarry. The low annual rainfall <br /> in the region and small drainage area make it unlikely that runoff would exceed the <br /> surface water storage capacity of the site and reach the Mokelumne River. <br /> As the excavated areas are backfilled with overburden, the loss of underlying <br /> coarse sand and gravel would reduce overall soil permeability and would result in a <br /> reduced rate of surface water percolation to the groundwater aquifer, and may increase <br /> the amount of water ponded on site. This could present health or safety hazards or <br /> reduce the agricultural value of the land if this water cannot be readily dispersed into <br /> the subsurface. This is considered a potentially significant impact. <br /> Reclamation Plan <br /> Reclamation of the proposed quarry would affect drainage, runoff, and <br /> groundwater recharge. Removal of underlying strata of rock, sand, and gravel, could <br /> reduce the permeability and water storage capacity of the site. Topographical lowering <br /> would cause a reduced hydraulic gradient within the soil water and may reduce gravity <br /> flow to the river, thereby slowing the rate of drainage. As a result, water may be more <br /> readily impounded on site unless an outlet to the Mokelumne River or other drainage is <br /> provided. Recharge to the aquifer may also be reduced, particularly as additional <br /> standing water would evaporate rather than percolate to groundwater. This is considered <br /> a potentially significant impact. <br /> If the reclaimed site elevation is closer to the water table and farming activities <br /> requiring irrigation are resumed, then the water table may be intersected at ground <br /> surface. This would increase the chances of flooding on site. Additionally, crops may <br /> have their root zone within saturated soils reducing the agricultural viability of this <br /> location. This is considered a potentially significant impact. <br /> 34 <br />