Abstract

Elkhead Creek near Craig, Colorado, is a sinuous, meandering stream whose lower 9 river miles have been regulated by Elkhead Reservoir and Dam since 1974. The U.S. Geological Survey, in cooperation with the Colorado River Water Conservation District, conducted a study from 2009 to 2010 that evaluated channel-pattern and cross-section changes and identified possible causes of streambank erosion in Elkhead Creek that could have been affected by Elkhead Dam and Reservoir. Aerial photographs taken from 1937 through 2009, streamflow records from water years 1953 through 2009, and channel surveys and sediment measurements made in 1997 and 2009 were used to analyze streambed and streambank erosion both downstream and upstream from the reservoir. Erosional trends were evaluated by calculating meander migration rates determined from analyses of georectified aerial photographs and from replicate channel surveys at monumented cross sections established in a previous study. The aerial photography dates defined four periods of roughly equal lengths for which mean meander migration rates were determined. Two periods were prior to and two periods were after Elkhead Reservoir was constructed.

First posted April 3, 2012