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Soil Erosion Soils found in San Francisco Bay and other parts of the nation naturally contain trace levels of copper. When soil washes off within urban areas, it carries copper to San Francisco Bay. While a certain amount of soil erosion is normal, human activities in Bay area watersheds have accelerated soil erosion. For example, soil is disturbed at hundreds of construction sites every year within the San Francisco Bay area. Stormwater Control Measures To prevent releases of soil and other pollutants into stormwater runoff, the State Water Resources Control Board requires all construction sites larger than one acre to obtain coverage under the statewide Construction General Permit and develop and implement Stormwater Pollution Prevention Plans. Municipal grading ordinances also require erosion and sediment control plans at sites where large quantities of soil are disturbed. Municipal agencies are implementing construction site inspection programs and outreach to require contractors to adhere to these plans. In addition, in accordance with municipal stormwater permit provisions, municipalities are requiring new and redevelopment projects that create one acre or more of impervious surface to provide stormwater treatment controls on-site to reduce stormwater pollution (including sediment loads) to the maximum extent practicable. Construction of new impervious surfaces also changes the quantity and timing of runoff flows in urban creeks. These changes can accelerate erosion of stream beds and banks which can contribute to sediment loads discharged to the Bay by streams. Municipalities are beginning to develop and implement hydromodification management plans and associated management measures to protect streams from increased potential for erosion and other impacts to beneficial uses. Since regulations exist to limit soil erosion and sedimentation, and municipalities have implemented control measures to address soil erosion from construction activities and hydromodification, it does not appear that additional control measures (relative to copper) are warranted. Wastewater Control Measures It is unlikely that soil erosion represents a significant or a controllable source of copper loading to Publicly Owned Treatment Works. Best Management Practices Best management practices information sources include: California
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