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The aquatic life ammonia standard is dependent on pH and temperature. <br />The detection limit for ammonia is 0.05 mg/1. All values above detection <br />limit are compared to table standards, page 87, found on this website: <br />http://www.epa.gov/waterscience/criteria/ammonia/99update.pdf <br />No ammonia excursions occurred this year. <br />PSCM runs two different mercury tests, a high level test with a MDL of <br />0.2 ug/l (for streams and NPDES sites) and a low level test with a MDL <br />of 0.0002 ug/l (for NPDES sites only). All high level test values (both <br />stream segments) this year were less than 0.2 ug/l. All low level tests <br />(both stream segments) were below the 0.01 ug/l stream standards. <br />NPDES Effluent Criteria (Permit No. CO-0000221). No excursions of NPDES <br />effluent limits occurred this year. <br />Surface Water Summary. Water discharged from the PSCM is not used <br />directly for irrigation. Indirectly, although, water discharged from the <br />mine is significantly diluted by water from either Fish Creek or the <br />Yampa River before it is diverted and used for irrigation. No irrigation <br />exists on Grassy Creek below the PSCM. Due to the relative amount of <br />dilution by additional water from both sources, the ambient water <br />qualities of Fish Creek and the Yampa River are the dominant factors in <br />determining their suitability for irrigation. Water discharged from the <br />PSCM is, however, used for livestock watering. <br />TDS values at NPDES3 are decreasing. TDS values at NPDES2 and NPDES4 <br />appear to be stabilizing. At lower Grassy Creek Site YSG5, the TDS trend <br />has stabilized. Of the eight spoil springs monitored, six are exhibiting <br />decreasing TDS trends, while two display a stable TDS trend. NPDES <br />discharges are normally suitable for livestock and irrigation, and <br />rarely exceed water quality standards for aquatic life. <br />TDS values at NPDES2 and lower Grassy Creek Site YSG5 were below the PHC <br />predicted values. The winter snowpack (as estimated from data at the <br />NCDC's Hayden Station) for this year was below average. All three NPDES <br />sites exhibited annual average flows below the historic averages. <br />20