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• Each well depletion Plan structure associated with an augmentation plan should be assigned a <br />priority date (administration number) to identify periods when the lagged well depletions are <br />in or out of priority with respect to downstream water rights. Absent other information, the <br />priority date for the well depletion plan structure should be based on the most junior ground <br />water right associated with wells in the augmentation plan. <br />Augmentation Plan Replacement Supplies and Recharge Accretions <br />The plans decreed in the 1970s and those subsequently filed and decreed typically follow a <br />similar mode of operations, based on the review of 12 augmentation plan decrees, conversations <br />with DWR personnel and ditch and reservoir company representatives, and review of data in <br />HydroBase and DWR's straightline diagrams. <br />• Diversions to recharge should be operated based on direct flow recharge water rights (for cfs <br />amounts) or recharge storage rights (for ac-ft amounts) with the ability to fill and refill when <br />the rights are in priority. Water rights specific to recharge use are difficult to extract from <br />HydroBase due to the many ditches decreed for recharge and multiple other uses. Therefore, <br />the information related to recharge water rights included herein are typically from decrees, <br />the straightline diagrams, and conversations with users. <br />• Due to the lack of specifics available for most recharge sites, it is recommended that recharge <br />sites be represented using: <br />- Specific capacities outlined in augmentation plan decrees or discussions with water <br />users, or <br />- Capacity equal to recharge storage right amounts (in ac-ft) plus direct flow right <br />amounts (in cfs) times 1.9835 ac-ft per cfs * 31 days per month. This approach <br />provides a demand for recharge "reservoir" ID to be modeled with the augmentation <br />plan. For example, an augmentation plan with a 100 cfs direct flow and two 400 ac-ft <br />recharge storage rights would have a total recharge storage capacity and target of <br />6,949 ac-ft (equal to 100 * 1.9835 * 31 + 2 * 400). <br />• Seepage loss rates should be assigned to recharge sites based on the engineering properties of <br />the underlying soils (e.g., standard permeability rates per Water District based on STATSGO <br />coverage) and an estimated average depth of five feet per recharge site. Recharge site <br />volumes, simulated diversions to recharge, and associated seepage losses should be used to <br />estimate the amount of un-filled capacity that can be filled in subsequent time steps. <br />• Diversions to recharge pit(s) should be simulated in priority year-round under the <br />augmentation plan recharge right(s) whenever excess capacity is available in the ditch. Ditch <br />losses should be accounted as input to recharge only during the non-irrigation season (i.e., if <br />no irrigation water is in the ditch). <br />• Accretions from seepage along the ditch length and/or multiple recharge sites under a <br />specific ditch augmentation plan are typically administered in aggregate on a monthly basis <br />below the main ditch headgate (for ditch plans) and/or above major calling rights (for ditch <br />plans and non-ditch plans). Model representation of river accretions should be accounted in <br />recharge Plan structures similar to how well augmentation plans are administered. <br />• Pumping augmentation wells to provide replacements directly to the river is typically done <br />when river depletions cannot be fully replaced by other sources. Lagged depletions from <br />augmentation well pumping represent an additional demand on the well augmentation plan. <br />13 of 16 <br />