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in April 1987. Review of its hydrograph shows that the peak flow this <br />year was the lowest since 1999. Its TDS plot indicates an increasing <br />trend. Baseline statistics for this site have been provided. <br />- NPDES 006 (NPDE56). This site is located on a tributary to Nubberson <br />Gulch referred to as the 006 Gulch. Construction of the 006 Pond was <br />Completed October 1989. This pond collects all mine discharges from the <br />cential mining area. The first hydrograph supplied shows data for this <br />year; the second shows all data collected since the site began <br />discharging. Review of the flow hydrographs indicates typical seasonal <br />variation due to snowmelt runoff in the spring,, with ,additional peaks <br />due to pit pumpage, pond clean-out, and rainfall events... The water year <br />average flow values .since this pond began to discharge arec <br />2001 0.080 cfs (monthly measurements) <br />2000 0.099 cfs (from monthly measurements as of 12/99) <br />1999 0.184 cfs (weekly measurements) <br />1998 0.317 cfs - -~ <br />X1997 0.393 cfs " <br />1996 0.194 cfs <br />1995 0.106 cfs <br />,1994 0.010 cfs <br />1993 0.127 cfs " <br />'1992 0.036 cfs <br />'1991 0.062 cfs " <br />1990 0.055 cfs (pond did not completely fill until March <br />' 29, 1990). <br />This years average flow value is 55Y~ of the historic (1990-2000{ average <br />flow value, 0.146 cfs. Flow values for this pond have been affected by <br />a 3.4 foot increase in spillway elevation on July 31, 1991, the <br />installation of a 4-inch orifice on the riser pipe on November 2, 1995, <br />and. the dredging of this pond that occurred in the summer of 1996 and <br />thefall of 1997. An upstream presettling pond was added in March 1998. <br />The principle spillway elevation was changed again, and the dewatering <br />orifice removed, in August 1998. Also affecting discharges from this <br />Id <br />