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- The end-of--month contents for the reservoirs with the most complete records (more <br />than about 75 percent of data record complete over 1950 to 2004 study period) were <br />summed. <br />- The monthly ratios of the summed monthly end-of--month contents to the total <br />capacity of the aggregate reservoirs were calculated. <br />- Missing monthly data for reservoirs in reservoir systems were estimated based on <br />decreed capacity times the monthly ratios calculated above for reservoirs with mostly <br />complete records. <br />- The complete end-of--month contents data sets were plotted and reviewed to identify <br />questionable data values. <br />Area-capacity curves <br />- Area-capacity curves were requested of the owners/operators since this information is <br />generally not available in HydroBase. <br />- Similar to the methodology used in previous CDSS modeling efforts for un-adjudicated <br />reservoirs and stock ponds, two-point area-capacity curves were used for storage facilities <br />if no related information was available. Area-capacity curves available for other key <br />reservoirs were reviewed in Task 69 to develop the following general rules to fill the two- <br />point curves for those reservoirs without area-capacity curves: <br />- Storage facilities were assumed to be 17-feet deep -area capacity points of (0,0) and <br />(capacity/17, capacity) <br />Monthly net evaporation rates and volumes <br />- Monthly net evaporation rates for structures throughout the SPDSS study area were <br />developed based on monthly gross evaporation less monthly effective precipitation data <br />at climate stations throughout the SPDSS study area. Key climate stations were assigned <br />to geographic areas throughout the SPDSS study area in Task 53.3. Several <br />methodologies were examined to distribute the point climate data over the spatial extent <br />of the SPDSS study area, as discussed in Task 53.3 Assign Key Climate Information to <br />Irrigated Acreage and Reservoirs memorandum. <br />Reservoir account ownership and storage capacities <br />- Information related to reservoir accounts and total, active, and dead storage capacities <br />specific to the facilities were requested during the interviews with the owners/operators. <br />Information gathered related to reservoir accounts and their operations are included in the <br />28 memoranda developed for SPDSS Task 5. <br />- Dead storage of zero (0) ac-ft was used if no related information was available. <br />- Active storage capacity equal to decreed storage capacity or maximum historical end-of- <br />month contents in HydroBase was used for smaller storage units within reservoir systems <br />if no related information was available. <br />• Maximum outlet release capacity <br />- Outlet release capacities are available for some reservoirs in HydroBase; this information <br />was also requested of the owners/operators. <br />Page 3 of 11 <br />