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• other stream sites established in tributaries of and along both Calamity and Tuttle Draws. With regard to the agricultural standards, only manganese was exceeded at all surface water monitoring sites, with the exception of the West Lateral irrigation ditch sites (SW-N104, SW-N105, SW-N106). Five sites have had exceedences of the pH standard and two sites have had exceedences of boron. Manganese was exceeded commonly in both Tuttle and Calamity Draws, as well as at sites located along tributaries to each drainage (SW-N6, SW-N7, NPDES 001 and 006, and SW-N102). Based on a classification of salinity hazard for arid and semi-arid areas (National Academy of Sciences,1972), surface water in Calamity and Tuttle Draws all fall within the category of waterthat can be used for tolerant plants on permeable soils with careful management practices (TDS from 2000 to 5000 mg/I). According to this classification system, water supplied by the West Lateral irrigation ditch (TDS 500 mg/I) will have no detrimental effects on plants. • Using mean values for sodium adsorption ratio (SAR) and specific conductance (SC, umhos/cm at 25°C) from each site determined for both the irrigation and non-irrigation season, water classifications were made based on guidelines proposed by the U.S. Salinity Laboratory (1954). During periods of irrigation (mid-April through mid-October), all surface water sites exhibit a low sodium hazard and a medium to high salinity hazard. Between irrigation seasons (with the exception of West Lateral Irrigation Ditch sites), all sites can be classified as having a low sodium hazard and a high to very high salinity hazard. As a result of the request made by OMLR to Peabody in a letter on May 4, 1986, Peabody revised the list of parameters that were analyzed for at all surface and ground water monitoring sites. The revised list included analyses for silver (total recoverable) and hexavalent chromium (total recoverable). The list was temporarily revised in order to determine whether silver and chromium were present in monitored water in sufficientand frequentenough concentrations towarrantfurther sampling for each, based on stream standards for the San Miguel River. During 1987, Peabody had its contract laboratory (ACZ Laboratories, Steamboat Springs, Colorado). perform total recoverable analyses for silver and hexavalent chromium on two sample sets collected at each • surface water site. In addition, Peabody collected water quality samples in April and October of REVISED JULY 2006 2.04.7-41