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<br />followed by an extended dry period in the late 1980's through 1992 that was found to <br />generally equal or exceed the deficits that occurred in the 1950's drought. <br />. The study period also includes 1977 which is the lowest year of discharge for six of <br />the seven basins. <br />. The use of a consistent study period for each of the seven basins is preferable over <br />the FWS study periods which differ by basin. <br />. The period generally follows completion of the major reservoir and diversion <br />projects which exist today and better represents operations on the river today. <br /> <br />Collection and Evaluation of Streamflow Records <br /> <br />Data from stream gaging stations in and near the stream reaches were collected and reviewed for <br />completeness during the study period. Monthly flows were generated using log transformations of <br />existing data to fill data gaps. The generated monthly flows were then distributed on a daily basis, <br />proportional to the daily flows at stations with complete gage records. The attached Figure I, taken <br />from the 1994 LRCWE report, shows the stream gaging stations. <br /> <br />Adjustments to Streamflow Records <br /> <br />Gaged and generated gage streamflow records were adjusted to reflect current (1992) depletion <br />levels. Major changes in use were identified through reviewing previous hydrologic studies, <br />contacting local representatives knowledgeable in the basin's water resources and evaluating <br />streamflow records for significant changes in runoff through the use of double mass curves. <br /> <br />To estimate current depletion levels by identified projects, the following criteria were used to guide <br />the evaluations: <br />. The maximum depletion for a given water resource project during the last three years <br />(1990-1992) was adopted as the current level of depletion. <br />. Depletions associated with a particular project were adjusted up to the current level <br />for other years. <br />. If previous years were greater than the 1990-1992 maximum, no adjustments were <br />made. <br />. Depletions associated with uses not identified as changing significantly, such as <br />irrigation, during the study period were assumed to remain unchanged and assumed <br />to be reflected in the gage flow. <br />. Gage adjustments were determined on an annual basis and distributed monthly <br />proportionate to the historic use pattern. <br />. For years of no data the monthly pattern of the selected year was used. <br />. Adjustments were made for increased transbasin exports and imports, new reservoirs, <br />and changes in reservoir operations. <br /> <br />4 <br />