Summary of fish communities along Underwood Creek, Milwaukee, Wisconsin, 2004–2019

Beginning in 2010, sections of Underwood Creek in Milwaukee County, Wisconsin, have undergone reconstruction to allow for improved fish habitat and better management of storm flows. In addition, dam and drop structures were removed to help improve fish migration while reintroducing several native fish species. With the reconstruction of Underwood Creek underway, the Milwaukee Metropolitan Sewerage District sought to evaluate if these measures have resulted in improvements to the fish community in the upstream parts of the watershed. The U.S. Geological Survey began sampling fish communities in 2004 at the farthest downstream site on Underwood Creek (Reach A) which was reconstructed in 2017. Reach B, which is slightly upstream, had undergone reconstruction in 2010 and fish community sampling began in 2016. A third reach farther upstream near Elm Grove was schedule to begin reconstruction in 2019. To compare the fish before and after reconstruction at the Elm Grove Reach, a fish community survey was conducted in spring of 2019 at Elm Grove and Reach B. This document describes the fish community from this sampling in comparison to previous surveys. Before reconstruction, Elm Grove Reach contained fish species more indicative of a slower, stagnant, warmwater stream than the other two rehabilitated reaches. Although six of the eight species found in Elm Grove Reach have been found at the lower reaches, all but two of the species are considered tolerant. Reconstruction of Elm Grove Reach to a similar habitat as the lower reaches will likely support a more diverse fish community.