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New study of Colorado River basin identifies second-century drought unmatched in severity


A new study by university and government researchers identifies a second-century drought unmatched in severity by the current drought or previously identified droughts in the upper Colorado River Basin.

The research was led by the Bureau of Reclamation and published in Geophysical Research Letters. It finds that compared to the current 22-year drought in the Colorado River, with only 84% of the average water flow, the water flow during a 22-year period in the second century was much lower at just 68% of the average water flow.

A press release issued by the Bureau of Reclamation says researchers reconstructed the streamflow at Lees Ferry to develop the new findings which are based on paleoclimatic data from tree-ring based Palmer Drought Severity Index values.

Water managers will use these extended records to understand whether droughts in the distant past were similar to or more severe than those observed in more recent centuries.

The baseline for the study’s analysis uses natural flow estimates data from 1906 to 2021 from the Lees Ferry gage.

It is anticipated that water managers will use this new extended data to better understand past droughts and plan for future ones.