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82 <br />• For mining operations these restrictions are between 20 and <br />30 mg of suspended solids in a liter of water (2, 38). This <br />value is so low that excellent analytical procedures will <br />have to be used to achieve any consistent results. In fact, <br />if water samples are sent out for suspended solids measure- <br />ments, send some replicates to check the precision of the <br />methods in the laboratory. At the level of 20 mg/1v of <br />suspended solids in water, an analytical laboratory needs <br />a balance capable of weighing.to 0.1 mg and a reliable <br />filtering apparatus which uses 0.45 pm membrane filters (13, <br />14). The analysis will have to be performed in a restricted <br />area which is clean and free of dust. Although the U.S.G.S. <br />manual -suggests_that__thecorrelation between__.turbidity and <br />suspended solids is subject to too many variations (13), it <br />• may be reasonable to attempt this on a restricted basis. <br />The precision of the diagnostic turbidity test could <br />be better than the specific analysis for suspended solids. <br />As of now, there is no easy method to do the analysis of sus- <br />pended solids and the standard methods should be used. <br />DISSOLVED SOLIDS ANALYSIS <br />Most waters will carry at least 300 mg/1 of dissolved <br />salts. Waters derived from glacier melting can fall below <br />100 mg/t. Consequently, if one liter of water is evaporated <br />to dryness, the residue is likely to be at least 300 mg. If <br />this is the case, the test can be made on a triple beam <br />balance if care is taken. Some precautions should be taken. <br />0 <br />