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The resulting "adjusted" hydrograph could then be used on Cochetopa Creek — Upper above the <br />LT by multiplying the "adjusted" gage discharge values by an area ratio; specifically, the area of <br />Cochetopa Creek — Upper above the LT (49.56 mil) to Cochetopa Creek near Parlin, CO (334 <br />mi2). The resulting proportioned hydrograph was itself "adjusted" (decreased) to reflect the <br />consumptive irrigation depletions and out -of -basin diversions upstream of the LT. The final <br />hydrograph thus represents a distribution of flow over time that has been reduced to reflect <br />existing human uses. <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 Cochetopa Creek — Upper is to <br />compute the Geometric Mean of the area- prorated "adjusted" data values from the Cochetopa <br />Creek near Parlin, CO hydrograph. This step is of value because of the inherent statistical <br />weaknesses found in any collection of data intended to measure natural stream discharge. <br />Without getting into the details of statistical theory, it is worth noting that a set of discharge <br />measurements is inherently inaccurate, no matter how well collected, due to the difficulties <br />attendant to data collection, especially hydrologic data. To give deference to this fact and to <br />increase the value of the hydrograph product of this analysis, the Geometric Means of the data <br />were computed and plotted along with the 95% Confidence Intervals about the data. The <br />resultant hydrograph, including recommended Instream Flow values, is displayed in Figure 1 <br />with the data displayed in Table 2. <br />-5- <br />