The Deer Island Restoration Project, Iowa

Story by Robert Jacobson

I finally had a chance to visit the Deer Island restoration site the week of April 1 (fig. 1).  Deer Island is a 2.5-mile long reach of the Missouri River near Little Sioux, Iowa where the US Army Corps of Engineers has nearly doubled the channel width while increasing habitat diversity.  Unlike all other shallow-water habitat (SWH) projects on the Lower Missouri River, the Deer Island project was designed to build habitat completely to the final condition.  Other projects have relied on a pilot channel or an initial widening effort that is expected to grow over time as the river takes advantage of the opportunity to erode and deposit sediment, adding habitat diversity by creating shallow, slow water.  The pilot approach minimizes construction costs – because the river does the work – but adds uncertainty about what the final state of the channel will look like and, critically, when it will be achieved.  The uncertainty about whether SWH restoration sites are still evolving means that evaluations of the SWH program have been aiming at a moving target. 

Figure 1. One of multiple rock and log structures at Deer Island restoration site. Photo is looking from east to west, across restoration area toward navigation channel.

The Deer Island site is fundamental to quantifying restoration on the Missouri River because it does not use a pilot approach and because it is located perfectly for a before/after comparison (fig. 2). An earlier USGS study on effects of the “spring rise” on pallid sturgeon habitat selected the exact same reach in 2006 because it was representative of the channelized Lower Missouri River between Sioux City, Iowa and Rulo, Nebraska. This study (Jacobson and others, 2009) developed detailed information about channel conditions, habitat availability, and background rates of channel change – a perfect pre-project comparison to quantify added habitat value. Ongoing biological and physical monitoring of the Deer Island site by the Missouri River Recovery Program – Habitat Assessment and Monitoring Project (HAMP) promises to help quantify the linkages between new habitat and biotic responses. 

Figure 2. Map of the Deer Island restoration site showing approximate limits of channel widening project and the area previously mapped and modeled by USGS.

 

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