Ecological impact of riverbank stabilization project in Nebraska

Increased agricultural activity within the Cedar River watershed, of central Nebraska, has reduced hydraulic retention throughout the basin and created flashier flow events.  The resultant flows have increased bank erosion and decreased riverine habitat complexity.  Wooden jetties were installed in several 1000m reaches of the Cedar River to reduce erosion and create aquatic habitat.   A two year monitoring program was begun in the spring of 2007 to determine the effectiveness of the jetties at both reducing erosion rates and improving habitat quality.  The monitoring program included comparisons of the macroinvertebrate, fish, and riparian plant communities of reaches with jetties against similar unaltered reaches.   Seven reaches with jetties and three unaltered reaches were sampled from May through October of 2007 and 2008.  Macroinvertebrates were sampled in May, July, and September 2007 and July 2008.  Riparian vegetation collections were conducted in August, and fish were collected in October of both years.  Sites with jetties were found to have significantly higher macroinvertebrate richness, diversity, and densities and have greater proportions of EPT taxa.  Riparian vegetation coverage was significantly greater at the stabilized sites and the stabilized sites had significantly more wetland plant species.  Stabilized sites also had significantly more native fish species.