2013-12-17_PERMIT FILE - C1992081 (18)

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• Site-Specific Surface Water Characteristics Information regarding the nature of historic atreamflow occurrence in Dry Creak in the vicinity of the Hayden Gulch Terminal loadout facility is presented in Attachment 7-3. Information pertinent to atreamflow includes peak flow estimates, drainage basin delineation and area, and site-specific baseline discharge and water quality maesuramenta. The following discussion is limited to discharge and water quality measurements conducted since 1985 at three surface water sites located at up- and downstream locations along Dry Creek in the vicinity of the Hayden Gulch Terminal loadout facility (sea Exhibits 12-1, 12-2, and Figure 13-1 in Tabs 12 and 13, respectively). Streamflow. Tablas 7-5, 7-6, and 7-7 present a listing of water quality analysis results including measurements of instantaneous diecharga collected from the up-stream (HGSD3) and downstream (HGSD2 and HGSD3) surface water monitoring sites elonq Dry Creek. Perusal oP the tables shows that flow generally increases in the downstream direction ' along Dry Creek, and on txo occasions (6/88 and 5/89) flow was observed at the downstream site (HGSD2) while the upetraem site (HGSD3) xae dry. This can probably be attributed to irrigation return £lox to Dry Creek from fields in the surrounding area • downstream of HGSD3. On two occasions, Dry Creek exhibited no flow at Sites HGSD3 and HGSD2, suggesting that the lower portion of Dry Creek near the Loadout is intermittent. At the upstream site (HGSD3), flox hen ranged from no flor to 126 cubic feet per second (c£e). During the spring anowmelt period (April - June) observed instantaneous diecharga ranged from no flow to 126 c£e and ranged Prom no flox to 21 c£e during the baseflow period (August - November). Discharge at the downstream site (HGSD2) has ranged from no Plow to 225 efa. During the enowmelt period (April - Juna) flow has bean measured at the lower ai to during each monitoring visit, ranging from < 0.5 cPa to 225 efs. Haseflow (August-November) monitoring of discharge at the downstream site has yielded measurements Prom no flow to 35 cfs. In October 1993, a second downstream site (HGSD3) wan established. This site is located +*~+•d++ately downstream of the Loadout in an attempt to eliminate potential contributions to Dry Creek Prom sources outside the permit area which could cause an inaccurate assessment of rater quality impacts. During the spring enowmelt period (April - June) obnervad instantaneous discharge at HGSD3 ranged from no flow to 26 efa and ranged from 0.14 cfs to 1.22 efa during the baaeflox period (August - November). Discharge monitoring along Dry Creak since 1985 in the vicinity of the Loadout indicates that irrigation activities above and /QN - o I 15 Revised 2/98