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Rainwater Harvesting Legal Framework <br />Page 3 <br />describe measurement, and provide proposed accounting (see additional discussion of <br />unique SWSP Application Requirements Section Q. <br />3. Collect two years of data to determine historic natural depletion as described in <br />37-60-115(6)(a)(11).2 The Criteria and Guidelines (201 9)3 also specifically require "a <br />minimum of two years of implementation of rainwater harvesting applied to <br />non -potable uses with advanced outdoor water demand management," and <br />replacement of 100 percent of the out -of -priority depletions (no credit for historic <br />natural depletion) during those two years. The Criteria and Guidelines specifically <br />require a two-year data collection period including operation of the rainwater <br />harvesting system applied to non -potable uses, which is an out -of -priority diversion. <br />Placing the water to beneficial use can only occur pursuant to an SWSP4. Data <br />collection, such as that related to weather data, could occur prior to the two years of <br />operation pursuant to an SWSP. <br />4. Based on at least two years of data collection, determine historic natural depletion <br />(the portion of historical precipitation that did not return to the natural stream system <br />due to vegetative cover evapotranspiration (ET)) and historical precipitation return <br />f lows: <br />Historical Precipitation <br />Historical Precipitation Return Flows <br />Historic Natural Depletion <br />"quantify the site-specific amount of <br />"amount of historic natural depletion... <br />precipitation that, under preexisting, natural <br />caused by the preexisting natural <br />vegetation conditions, accrues to the natural <br />vegetative cover evapotranspiration" <br />stream system via surface and groundwater <br />37-60-115(c)(1) <br />return flows" 37-60-115(6)(a) <br />Determine the historic natural depletion of precipitation intercepted by surfaces made <br />or to be made impermeable by the pilot project. Pursuant to 37-60-115(c)(1), this is <br />the amount of depletion that does not need to be replaced when operating pursuant to <br />an SWSP after the first two years of operation and data collection. This is also the <br />amount of precipitation that "would not have accrued to a natural stream under <br />preexisting, natural vegetation conditions" and can be consumed without replacement <br />under a permanent augmentation plan pursuant to 37-60-115(c)(11)(A). <br />2 Create a baseline set of data and sound, transferable methodologies for measuring local weather and <br />precipitation patterns that account for variations in hydrology and precipitation event intensity, <br />frequency, and duration, quantifying preexisting, natural vegetation consumption, measuring <br />precipitation return flow amounts, identifying surface versus groundwater return flow splits, and <br />identifying delayed groundwater return flow timing to receiving streams; <br />3 Page 4, paragraph 2 <br />4 The SWSPs described in this memo are authorized in accordance with Section 37-92-308(4) and 308(5). <br />They are referred to in shorthand as 308(4) SWSP, where there is a corresponding water court <br />application for an augmentation plan, and 308(5) SWSP, where there is not a corresponding water court <br />application. <br />