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• water that regulate its suitability for an ultimate use. The four categories of water quality standards are: 1) domestic drinking; 2) aquatic life; 3) irrigation; and 4) livestock. Yampa River receiving stream water quality standards (Section 13) for the Seneca II-W complex are covered in the four water quality standard categories named above. Historical geochemical data for samples collected at each surface site were evaluated by a computer program. The program checks to see if the value for a sample analyte concentration is greater than the value established as a water quality standard. If the sample value exceeds the standard value, then the program notes which surface site has an analyte concentration that exceeds the standard. The results of the program executed for each category of water quality standards are summarized in Tables 7-24 through 7-27. Due to the lack of consistent types of analyses for trace elements and the variability of lower limits of analytical detection among particular types of analytes, some comparisons were indeterminable or suspect. In numerous instances, the sample analyte concentration is lower than the analytical limit of detection. Also, the lowest limit of detection may be higher than the water quality standard in some instances. If either one of the above • instances occurs when the program is making the comparison, the spring site with the questionable data is marked with an asterisk 1*). Spring sites marked by the asterisk are not considered as sites that have analyte concentrations which exceed a water quality standard, but are deemed suspect instead. Domestic Drinking Water Suitability. Information presented in Table 7-14 indicates that spring water at most of the spring sites in the Seneca II-W complex is unsuitable for domestic and drinking water purposes. Selenium and Zn standards were exceeded at two sites. Cadmium and F standards were exceeded at two sites. Ammonia (NH3) and N03 standards were exceeded at three sites. The Fe standard was exceeded at four sites. Exceedences for sulfide are considered suspect because of the asterik designation. The Mn standard was exceeded at seven sites. The SO standard ryas exceeded at ten sites. The 4 250 and 500 mg/1 standards for TDS were exceeded at 11 sites. Sites 51, 59, 523, 525, 535, 541, and 545 have an exceedence for a maximum contaminant level (MCL) standa rd as defined for Cd, F, N0 , and Se i n 40 CFR 141.11 (1986). Based on the number of sites that 3 have ex ceedences for ten water quality standards, most Seneca II-W spring water would require some type of treatment before it would be suitable for domestic drinking water • purposes. 73