Most hydrologic analyses, whether for appraisal of the water resource, feasibility of a particular development, design of a system of operation, assessment of gains or losses from acts of man or natural changes, or almost any other use, require the extension in time of some streamflow records. In the Upper Colorado River Basin, streamflow records have been extended by various agencies from time to time to fulfill their individual needs, resulting in different estimates of flow for the same point and time. The purpose of this report is to provide correlative estimates of monthly mean discharge at discontinued streamflow gaging stations so that all users will have access to a single set of data.
Estimates of monthly mean discharge for periods other than the period of actual record are given for certain discontinued streamflow gaging stations. The stations selected were discontinued in recent years, but they have a sufficient length of record to permit development of a meaningful correlation with the records for a nearby long-term gaging station. Where possible, estimates of monthly mean discharge are made to provide a complete record, estimated or measured, from 1930 to 1965. However, where the long-term gaging station record encompasses a shorter period, the estimates cover only that shorter period. Estimates for periods prior to 1930 were not made, although these may be computed for a few stations. Lack of a related long-term gaging-station record prevented the extension of records at many discontinued stations.
The area covered in this report (fig. 1) is that defined in the Colorado River Compact of 1922, as the Upper Basin "those parts of the States of Arizona, Colorado, New Mexico, Utah, and Wyoming within and from which waters naturally drain into the Colorado River System above Lee Ferry,"1 but excluding "all parts of said States located without the drainage area of the Colorado River System which are now and shall hereafter be beneficially served by waters diverted from the System above Lee Ferry" (Wilbur and Ely, 1948, p. A18).
