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for all ground water quality data). All ground water samples collected in 1990 or after were analyzed for the <br />chemical parameters presented in Table 15-4. <br />PWCC's Yoast baseline surface water monitoring program, starting in 1990, consisted of three sites on <br />Sage Creek, two sites on Y1 Gulch (a previously unnamed tributary to Sage Creek), one site on the Annand <br />Draw (a previously unnamed tributary to Grassy Creek), and one site on Grassy Creek. Semiannual spring <br />surveys, beginning in 1991, identified ten springs in the Yoast areas. See Table 15-2 for details of these <br />stream and spring monitoring sites. <br />PWCC generally monitored the surface water sites for flow and feld parameters (temperature, pH, and <br />electrical conductivity) monthly from March to October. Winter months were excluded from monitoring due <br />to low flow conditions, the presence of thick icepack on the stream surfaces, and inaccessibility. Samples <br />for lab analysis were generally collected triannually in 1991 and monthly in 1992 and 1993. All surface and <br />spring water lab samples were analyzed for the chemical parameters presented in Table 15-5. <br />Operational Hvdrolooic Monitoring Program <br />Water Monitoring Techniques. Raw water samples are taken from the sampling site and placed into <br />specially prepared sample bottles. Dissolved constituent samples are filtered in the field with a 0.45 micron <br />filter membrane. Water samples are chilled by packing the bottles in iced coolers, and promptly taken to a <br />laboratory for chemical analysis using EPA approved methods. The types of preservatives and bottles used <br />in the monitoring program are contained in Table 15-5. <br />All water samples are field tested for pH, temperature, and electrical conductivity (corrected to 25°C) at the <br />time they are collected. The pH meter is calibrated before each day's use by performing a lwo-point <br />calibration using pH 7.0 and 10.0 buffer solutions. Single point calibration checks are performed in fhe <br />field. Conductivity meter calibrations are performed daily using potassium chloride solutions varying in <br />strength from 1000 up to 3000 umhos/cm. Surface and spring water quality samples are collected by grab <br />sampling. Flow monitoring procedures vary with the amount of flow. Low flows are measured with a bucket <br />and stopwatch, or a portable cutthroat flume at a small drop in the stream channel. High flows are <br />computed using measurements of the stream <br />u <br />12 <br />