The U.S. Geological Survey (USGS), in cooperation with the Dane County Land Conservation Department (LCD) and the Wisconsin Department of Natural Resources (DNR), investigated the instream effects from construction of a residential subdivision on Brewery Creek in Dane County, Wisconsin. The purpose of the investigation was to determine whether a variety of storm-runoff and erosion-control best-management practices (BMPs) would effectively control the overall sediment load, as well as minimize any hydrologic, ecologic, and geomorphic stresses to Brewery Creek.
Stormwater volumes decreased 60 percent from the preconstruction phase to the land-disturbance phase and slightly increased (9 percent) from the land-disturbance phase to the home-construction phase. The stormwater volumes were applied to total solids and total suspended solids concentrations to compute a solids load for each contaminant. Total and suspended solids load indicated a similar trend from preconstruction to land-disturbance phases with decreases of 52 and 72 percent, respectively. Both total and suspended solids load continued to decrease in the transition from land-disturbance to home-construction phases, by 22 and 37 percent, respectively. However, because of variability in the data, statistically there was no change in the magnitude of difference between the upstream and downstream solids load from one phase of construction to the next at the 90-percent confidence level.
Other physical, biological, and ecological surveys including macroinvertebrates, fish, habitat, and geomorphology were done on segments of Brewery Creek affected by the study area. Macroinvertebrate sampling results (Hilsenhoff Biotic Index value, or HBI), on Brewery Creek ranged from 'very good' to 'good' water-quality with no appreciable differences during any phase of construction activity. Results for fish-community composition, however, were within the 'poor' range (Index of Biotic Integrity value, or IBI) during each year of testing. A general absence of intolerant species, with the exception of brown trout, reflects the low IBI values. Habitat values did not change significantly from preconstruction to postconstruction phases. Although installation of a double-celled culvert in Brewery Creek most likely altered the width-to-depth ratio in that reach, the overall habitat rating remained 'fair'. Fluvial geomorphology classifications including channel cross sections, bed- and bank-erosion surveys, and pebble counts did not indicate that stream geomorphic characteristics were altered by home-construction activity in the study area. Increases in fine-grained sediment at various cross sections were attributed to instream erosion processes, such as bank slumping, rather than increases in sediment delivery from the nearby construction site.
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|series||unknown||Scientific Investigations Report|
|journal||Scientific Investigations Report|