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human uses. In the case of Alpine Gulch there are no existing diversions and thus no need to <br />make adjustment for depletions. <br />{The Following discussion is based upon the US Geological Survey's Techniques of Water - <br />Resources Investigations Series, Book 4: Hydrologic Analysis and Interpretation, Chapter A3: <br />Statistical Methods in Water Resources (Chapter 3: Describing Uncertainty) by D.R. Helsel and <br />R. M. Hirsch. This technical reference provides the scientific background and guidance <br />important to the systematic interpretation of hydrologic data. The document is available online <br />and is a valuable aid to understanding and interpreting the analyses described here.} <br />The next step in producing a representation of the discharge at Alpine Gulch is to compute the <br />Geometric Mean of the area- prorated "adjusted" data values from the Mineral Creek above <br />Silverton, CO hydrograph. This step is of value because of the inherent statistical weaknesses <br />found in any collection of data intended to measure natural stream discharge. Without getting <br />into the details of statistical theory, it is worth noting that a set of discharge measurements is <br />inherently inaccurate, no matter how well collected, due to the difficulties attendant to data <br />collection, especially hydrologic data. In this particular case, the short period of record lends <br />even greater merit to the use of this statistical tool. To give deference to this fact and to increase <br />the value of the hydrograph product of this analysis, the Geometric Means of the data were <br />computed and plotted along with the 95% Confidence Intervals about the data. The resultant <br />hydrograph, including recommended Instream Flow values, is displayed in Figure 1 with the data <br />displayed in Table 2. <br />-5- <br />