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Abstract
Chemical dilution methods of streamgauging with sodium dichromate were tested in a tilted laboratory flume for flows up to 5cfs and at various locations on a range of natural streams for flows up to 210 cfs. Accurate check calculations of flow were available with the flume tests and these indicted probable errors of plus or minus 4.5 percent for the constant injection method. In turbulent sections of natural streams this method was found to have about the same accuracy as current meter gauging under ordinary flow conditions although successful applications required careful attention to details that are readily overlooked. Similar orders of accuracy were obtained with the sudden injection method but this method required extra laboratory work and an inconveniently large number of samples. It was concluded that the constant injection chemical gauging technique with sodium dichromate is a useful ancillary method with special advantages over current meters in certain circumstances. However, it does not appear to be superior to the current meter method when reasonable conditions for the latter are available.