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<br />DATA AVAILABILITY
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<br />Streamflow Records
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<br />Daily streamflow records were available (either publ ished or in computer
<br />files) for 79 streamflow-gaging stations in the basin for varying time periods
<br />during water years 1901-76 (Steele and others, 1979, table 6 and fig. 14). Rec-
<br />ords for 36 of the 79 streamflow-gaging stations within the Yampa River basin were
<br />used to compute monthly and annual summaries of flow conditions for use in the
<br />reservoir analysis. The location of these stations' is shown in figure 3 with the
<br />same map-numbering scheme as used by Steele and others (1979), and the periods of
<br />available record for the stations are shown in figure 4. More than 777 years of
<br />daily records were available for these 36 stations.
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<br />A matrix of monthly and mean annualstreamflows was developed for water years
<br />1910-76 by using the existing station records. Approximately two-thirds of the
<br />data were computed by a "least-error," linear-regression technique based upon
<br />interstation correlation of streamflow discharge (A. W. Burns, U.S. Geological
<br />Survey, written commun., 1976). Either measured streamflow data or a combination
<br />of measured and synthesized streamflow data were used to determine what is termed
<br />in this report as "historic conditions" for the model-analysis period (water years
<br />1927-76). No attempt was made to adjust the records of monthly streamflow data
<br />for changes in water use that occurred during water years 1910-76. Monthly and
<br />mean annual streamflow values were used in the study for the following purposes:
<br />(1) To determine inflows to individual proposed reservoirs, (2) to develop a mass-
<br />balance analysis for existing streamflow conditions at selected points in the
<br />basin, and (3) to serve as a reference base for describing hydrologic changes due
<br />to reservoir development.
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<br />Precipitation
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<br />Monthly precipitation data were available for 13 sites within the basin--
<br />2 sites near Dinosaur National Monument and 1 site near Rabbit Ears Pass (Colorado
<br />Water Conservation Board and U.S. Department of Agriculture, 1969). Because' of
<br />longer record lengths and the proximity of the sites to the area of interest with-
<br />in the basin, data were used from only six of these sites (fig. 5). The sites in-
<br />cluded Steamboat Springs, Hayden, Columbine, Pyramid, and Craig, in Colorado; and
<br />Dixon in Wyoming (fig. 5). For each of these sites, varying amounts of monthly
<br />precipitation data were available. A complete data matrix of total monthly pre-
<br />cipitation was needed for water years 1910-76. The same technique as noted for the
<br />streamflow data (A. W. Burns, U.S. Geological Survey, written commun., 1976) was
<br />used to provide missing precipitation data within the data matrix. The monthly
<br />precipitation values were used in the study to determine amounts of monthly rain-
<br />fal I on the surfaces of each of the proposed reservoirs used in the analysis. The
<br />compieted monthly precipitation record for the nearest one of the six sites was
<br />directly appl ied to each proposed reservoir, as noted in table 1.
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