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- Surface Water Site SW-52W-SG7 (WSH7). This site is located on • Hubberson Gulch upstream of the confluence of mine discharges contained in the 006 Gulch, but is downstream of Ponds 016 and 017. Monitoring here began in April 1987. Review of its hydrograph shows that the peak flow this year was the lowest since 1994. Its TDS plot indicates an increasing trend. Baseline statistics for this site have been provided, - NPDES 006 (NPDES6). This site is located on a tributary to Hubberson Gulch referred to as the 006 Gulch. Construction of the 006 Pond was completed October 1989. This pond collects all mine discharges from the central mining area. The first hydrograph supplied shows data for this year; the second shows all data collected since the site began discharging. Review of the flow hydrographs indicates typical seasonal variation due to snowmelt runoff in the spring, with additional peaks due to pit pumpage, pond clean-out, and rainfall events. The water year average flow values since this pond began to discharge are: 2002 0.186 cfs (monthly measurements) 2001 0.080 cfs " 2000 0.099 cfs (from monthly measurements as of 12/99) 1999 0.184 cfs (weekly measurements) 1998 0.317 cfs " 1997 0.343 cfs " 1996 0.144 cfs " 1995 0.106 cfs " 1994 0.010 cfs " 1993 0.127 cfs " 1992 0.036 cfs " 1991 0.062 cfs " 1990 0.055 cfs (pond did not completely fill until March 29, 1990). This years average flow value is 127 of the historic (1990-2002) average flow value, 0.146 cfs. The reason of the high average flow in a drought year was a high snowmelt runoff flow in early April caused by unusually warm weather. Flow values for this pond have been affected by a 3.4 foot increase in spillway elevation on .luly 31, 1991, the installation of a 4-inch orifice on the riser pipe on November 2, 1995, C J • I 14