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42 <br />an on-site analytical program has been established, and the <br />regulatory agencies are convinced that effluent operations <br />are under proper control, on-site indicator tests can perhaps <br />be substituted for more expensive specific tests. In this <br />regard, the above tests should suffice in most instances. <br />Most of the basic tests are self-explanatory. Standard <br />procedures for analysis can be found in most water analysis <br />guides (13, 14). In the Appendix, procedural guidelines <br />for some of the water tests are suggested. The one test <br />that requires explanation is conductivity. <br />Conductivity of Mine Drainages <br />Conductivity,or specific conductance, is a numerical <br />expression of the ability of water to carry electrical cur- <br /> rent. It is usually measured in micro mho/cm (umho/cm) where <br /> a mho is the inverse of resistance in ohm. Pure water is <br />a poor conductor; it has a conductivity of O.S-4 umho/cm. When <br />ions are present in the water from soluble salts or strong <br />acids and bases the conductivity is much higher. Natural <br />waters range between 50 to 1500 umho/cm. Reviews on the <br />measurement of conductivity and how it varies in water can <br />be found in Hem (7) and in the Wastewater Manual (13). <br />Effluents issuing from mines typically contain ionic <br />species and suspended solids. They carry only minor amounts <br />of nonionic dissolved material such as dissolved organic <br />compounds. The total dissolved organic carbon in 11 mine <br />drainage waters in the Front Range of Colorado ranged from <1 <br />U