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We evaluated the effects of dam removal on fish assemblage structure and spatial distributions after four low-head dam removals in the Baraboo River, Wisconsin, using data collected at 35 study sites over 7 years. After dam removal, biotic integrity scores (possible range ¼ 0–100) increased by 35–50 points at three of the four former impoundments as a result of decreases in percent tolerant species, increases in the number of intolerant species, and in some cases, increases in species richness. Fish assemblage shifts were muted at a fourth, lower-gradient impoundment site, indicating that responses differ among dam sites within a river system. In tailwater areas, postremoval assemblage shifts were transient;...
Categories: Publication; Types: Citation; Tags: 183, 184, 185, 19, 29, All tags...
We investigate stream response to the La Valle Dam removal and channel reconstruction by estimat- ing channel hydraulic parameter values and changes in sedimentation within the reservoir. The designed channel reconstruction after the dam removal included placement of a riffle structure at the former dam site. Stream surveys undertaken in 1984 by Federal Emergency Management Agency and in 2001 by Doyle et al. were supple- mented with surveys in 2009 and 2011 to study the effects of the instream structure. We created a model in HEC- RAS IV and surface maps in Surfer© using the 1984, 2009, and 2011 surveys. The HEC-RAS IV model for 2009 channel conditions indicates that the riffle structure decreases upstream channel...
Categories: Publication; Types: Citation; Tags: 32
The ability to predict the effects of dam removal in highly sediment-filled systems is increasingly important as the number of such dam removal cases continues to grow. The cost and potential impacts of dam removal are site-specific and can vary substantially depending on local conditions. Of specific concern in sediment-impacted removals is the volume and rate of reservoir deposit erosion. The complexity and potential accuracy of modeling methods used to forecast the effects of such dam removals vary substantially. Current methods range from predictions based on simple analysis of pre-dam channel geometry to sophisticated data-intensive, three-dimensional numerical models. In the work presented here, we utilize...