Upper Green River Basin streamflow reconstructions and drought variability

The upper Green River represents a vital water supply for southwestern Wyoming and Upper/Lower Colorado River Compact states. Rapid development in the southwestern U.S. combined with the recent drought has greatly stressed the water supply of the Colorado River system and has increased interest in historic streamflows. The current research developed proxy records (streamflow) derived from tree ring chronologies in the Upper Green River Basin (UGRB). These streamflow reconstructions provide an effective way to analyze patterns of drought over a period of time extending beyond any instrumental record.;Nine streamflow reconstructions were developed for both headwaters stations (utilizing unimpaired streamflow records) and stations lower in the basin (utilizing naturalized streamflow records). Traditionally, streamflow reconstructions have mostly been limited to large rivers, but reconstructing headwaters records provides information to water users in the upper basin as well as providing spatial variability in streamflow throughout the river basin. In this study, all upper basin reconstructions extended back to the year 1615. The most downstream station in the UGRB (Green River near Greendale, UT) was extended to 1439 A.D. The coefficient of variance explained (R2) for this reconstruction is 0.65.;Different modes of drought were identified within this reconstruction. Annual extremes (wet and dry) and persistent wet and dry (drought) periods were identified compared with long term trends in the reconstructed streamflow record.