In 2009, the U.S. Department of Agriculture through the National Resources Conservation Service (NRCS) began the Mississippi River Basin Healthy Watersheds Initiative (MRBI) to work with landowners to implement voluntary conservation practices designed to reduce nutrients entering the Gulf of Mexico. The goal of the MRBI program is to improve water quality, restore wetlands, and enhance wildlife habitat while ensuring economic viability of agricultural lands in high-priority watersheds within the Mississippi Basin (USDA, 2017). However, watershed-scale evaluations identifying specific pollution sources and the conservation practices needed to improve water quality are needed to aid field office staff responsible for working with landowners. Therefore, a comprehensive planning effort aimed at prioritizing specific landscapes, crop types, and the conservation practices available is needed to help NRCS field staff implement the MRBI program where it will be the most effective considering limited available resources.

The Missouri State Office of the NRCS contracted the Ozarks Environmental and Water Resources Institute (OEWRI) at Missouri State University (MSU) to perform a watershed assessment study for three HUC-12 watersheds within the Lower Grand River watershed, Turkey Creek (102801031301), Spring Branch-Elk Creek (102801031302), and Long Branch (102801031204) located in Linn, Chariton and Sullivan Counties, Missouri. Soil and streambank erosion has been identified as major concern for water quality for streams within the Lower Grand River watershed and water quality monitoring shows high levels of nutrients, bacteria, and suspended sediment (MDNR 2014). Sections of the Lower Grand River downstream of the these three watersheds are listed under the Missouri Department of Natural Resources (MDNR) Section 303(d) list of impaired waters for E. Coli pollution (MDNR, 2018A). Furthermore, the Turkey Creek watershed and the Spring Branch-Elk Creek watershed flow directly into Silver Lake on the Swan Lake National Wildlife Refuge that has experienced recent sedimentation problems (USFWS 2011). Additionally, Long Branch flows into West Yellow Creek just upstream of one of the water supply intakes for the City of Brookfield, Missouri. The purpose of this assessment is to provide NRCS field staff with the necessary information to identify locations within the watershed where soil, slope, and land use practices have the highest pollution potential and to describe conservation practices that can be the most beneficial to improve water quality. The specific objectives of this assessment are to: (1) Complete a comprehensive inventory of existing data in the watershed including information related to geology, soils, hydrology, climate, land use, and any existing biological or chemical monitoring data available;
(2) Perform a resource assessment of the watershed that includes analysis of the data gathered in the watershed inventory that includes identification of nonpoint source pollutants, water quality impairments, rainfall-runoff characteristics, and a field-based stream bank conditions assessment;
(3) Provide NRCS staff with information on the resource concerns within the watershed, specific field conditions that contribute that most to the water quality impairment, and what conservation practices should be implemented for the existing conditions to get the most water quality benefit.

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Completed for Natural Resources Conservation Service, United States Department of Agriculture

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