Prioritizing stream restoration: a decision support tool for use in restoring waters impaired by excess sediment in the Blue Earth River Basin of Minnesota

Abstract

The hydrology of the Blue Earth River Basin has been dramatically altered following European settlement in the mid-to-late 1800's. Land use change has resulted in hydrologic instability leading to streambank and bluff erosion and increased sediment transport (Magner et al., 2003). Hydrologic change has led to an increase in Turbidity, or cloudiness of the river commonly measured as total suspended sediment (TSS). Excessive turbidity in water can be harmful to both humans (if used for drinking water) and aquatic life. In the Greater Blue Earth River Basin, there are 39 stream/river reaches that fail to meet the state's water quality standards for Turbidity, which is 90 parts per million TSS (MPCA, 2005). The purpose of this study is to create a tool that researchers can use to prioritize stream restoration in the Blue Earth River Basin in a relatively quick, productive and cost-effective way. The tool created will help prioritize stream sites for restoration based on a set of decision support metrics. A field test of the tool was conducted on two tributaries to the Blue Earth; Elm and Center Creek. The tool was tested on a total of 30 sites from these two tributaries. The future goal for this tool is for it to be used to help local officials prioritize restoration on unstable areas throughout the Blue Earth River Basin that are actively eroding and contributing sediment to the Blue Earth River.