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<br /> <br />Discharge and water quality should be monitored at the highway neaz the mouth of this <br />tributary when possible. <br />Roan Creek is a perennial stream that drains a much larger area relative to Logan Wash. Roan <br />Creek discharges directly into the Colorado River with its confluence downstream from the <br />town of DeBeque. The U.S. Geological Survey (USGS) does not currently operate any stream <br />gages on Roan Creek. However, two stream gages were identified on Roan Creek during the <br />site reconnaissance; Roan Creek above Logan Wash approximately 500 feet downstream from <br />Conn Creek, and Roan Creek at DeBeque. Both of these gages aze currently maintained and <br />operated by Richard Pilan & Associates of Grand Junction on behalf of oil companies. Further <br />investigation into the availability of streamflow data from these gages will be undertaken to <br />document water quality in Roan Creek upstream and downstream from the LWM facilities for <br />future permitting purposes. <br />2.3 SAMPLING FREQUENCY <br />Seasonal flow and water quality data are necessary to fully characterize influent to the pond, <br />and potential effluent water quality. Logan Wash is located in a semi-arid area of western <br />Colorado which receives variable precipitation depending on season. The wash ranges in <br />elevation from 8,800 ft-mean sea level (MSL) at its headwaters to 5,200 ft-MSL at its <br />confluence with Roan Creek. The pond is located at approximately 5,400 ft-MSL elevation. <br />The Logan Wash watershed aspect is west, and thus a relatively sharp contrast between south <br />and north facing slopes is present. The average annual precipitation is 12 to 16 inches in the <br />lower portion of the watershed and up to 20 inches in the headwater azeas (CCC, 1984). <br />A seasonal snowpack is expected to accumulate in the watershed from December through <br />March during most yeazs, with greater accumulation at higher elevations and north-facing <br />slopes. This seasonal snowpack begins melting in March and April and is essentially melted <br />by June during most yeazs. Although no streamflow gaging information is available for Logan <br />Wash, snowmelt likely generates streamflow in April or May each yeaz. Streamflow is also <br />likely following heavy summer rainstorms. During interim periods between snowmelt or <br />rainfall events, Logan Wash is dry as observed during the November 1995 reconnaissance. <br />The frequency of surface water measurement and sampling must revolve around the seasonal <br />nature of surface and subsurface flow in the watershed. More frequent sampling is <br />recommended during the spring snowmelt period and less frequent sampling is required during <br />11 <br />