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<br />000586 <br /> <br />The Performance Index is based on the premise that the course designer can create <br />good recreational conditions by manipulating the hydraulics, geometry, streambed and <br />overbank areas of the stream. For this, the site must have design flexibility, or be <br />readily modifiable to allow design flexibility. The acceptable conditions could be <br />measured in velocities, stream width, wave size, hydraulic jump formation, and depth but <br />in this method, would be unnecessary. The acceptable conditions are a result of the skill <br />and sensitivity of the designer in shaping the available flow over a given length and drop <br />within the river corridor. <br /> <br />Using the Performance Index methodology, a marginal site in terms of flow rates, <br />hydraulic gradient, and site flexibility can be identified and deemed appropriate or <br />inappropriate for an RICD water right. <br /> <br />The CWCB does not intend for the Performance Index to be used in evaluating the <br />upper end of potential flow rates requested at a proposed RICD site. The ewCB <br />intends for the Performance Index to be used to evaluate the appropriateness of a <br />specific stream reach for a proposed RICD water right. Provided below are three <br />sample computations to demonstrate the use of the Performance Index. <br /> <br />Hypothetical Scenario #1 <br />The town of Riverdale, Colorado desires to obtain an RICD water right for a stream <br />reach located within their community for the purpose of developing a whitewater <br />boating course. The proposed length of the boating course is 850 feet, and the total <br />drop of the natural stream within that reach is 6 feet. The requested RICD flow rate <br />is 200 cfs. <br /> <br />Evaluation <br />The average stream slope = 6'/850' = 0.0071 ft/ft <br />The requested flow rate = 200 cfs. <br />The Performance Index (PI) = (0.0071 x 2(0) x 100 = 141 <br /> <br />Based on a PI of 141, the ewCB would recommend that the proposed reach is <br />appropriate for the requested RICD since the PI exceeds the minimum <br />recommended PI of 75, and since the requested flow rate is less than the ewCB's <br />recommended maximum RICD flow rate of 350 cfs (as presented in the main body <br />of this document - see Section 5) <br /> <br />12 <br />