Water Resources Collections and Archives

An increasing number of stream restoration projects include structures such as vortex rock weirs to provide grade control. These structures are becoming a preferred option because they pair physical creek stability with the secondary benefit of habitat enhancement. Due to the monetary investment in these restoration strategies, it is essential to evaluate the contributions these structures make both in terms of stability and habitat. This study adopts existing methods for evaluating vortex rock weir stability and develops a new method for examining potential habitat based on the assumption that physical complexity may lead to suitable habitat. These methods for assessing weir stability, physical complexity, and potential habitat were successfully implemented at the Penitencia Creek and Wildcat Creek restoration sites in an attempt to correlate weir stability with physical complexity. Wildcat Creek's structures scored consistently lower than Penitencia Creeks' in the stability assessment. These results mimic results in the literature that find vortex rock weirs fail structurally after ten years in operation. In addition, variance for each of the physical parameters was calculated and compared to a trapezoidal control channel; the results of this analysis indicate that as weirs begin to fail, physical complexity decreases, and the presence of complexity within the system becomes increasingly unpredictable. In evaluating the methods used, we find the criteria for assessing vortex rock weir structural integrity is straightforward and simple, while the complexity measurements are demanding and time intensive. Despite this, coupling the weir stability criteria with the physical complexity analysis provides a powerful tool to assess the physical stream response to vortex rock weirs and other in-stream structures.