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Grassy Creek Drainage. Four monitoring sites lie within the Grassy Creek drainage: Site 1, located upstream on Grassy Creek; NPDES Discharge Point 00:3, also known as the Shop Reservoir or the Northwest Impoundment, located just north of the mine shop area; Site 2, located approximately 0.1 mile downstream of where NPDES 003 discharges into Grassy Creek; and Site 3, which monitors discharges from pre-SMCRA mining areas and is located adjacent to Site 2. - Surface Water Site SW-52-1 (SSG1). This site monitors Grassy Creek upstream of mining by the Seneca II Mine. It was dry in October 2003 and August and September 2004. Review of the TDS plot indicates a slightly increasing trend. NPDES Discharge Point 003 (NPDES3). Hydrographs presented in Appendix D show that flow has increased at this site since September 18, 1984, when operation of the truck wash system began. Water is siphoned from . the Wadge Impoundment (NPDES 002) into a holding pond . Overflow from the holding pond is di verted into the shop ditch, which flows into NPDES 003. Water is pumped from the holding pond to the wash rack, drains into a settling pond, and then into the same shop ditch. This operation has increased the i`_low at NPDES 003 while decreasing the flow at NPDES 002. Other events have zffected the long-term hydrograph at NPDES 003. They include the diversion away from NPDES 003 of the runoff from an inactive fly ash pit (operated by the Hayden Station power plant) in October 1980 and the diversion away from NPDES 003 of runoff contained in the Northwest Diversion Ditch (see the Seneca II Permit Application, Exhibit 7-7, Surface Water Hydrology Map and also the 1982 Seneca II AHR) in April 1982. Discharge volumes at the 003 site have also been affected by the reduction in diameter of the discharge culvert (36 inches to 6 inches) that occurs~ed on July 19, 1988. Finally, a smaller volume pump and line from 002 to the truck wash was installed in August 2001. 17