In 2012, the U.S. Department of Agriculture through the National Resources Conservation Service (NRCS) implemented the National Water Quality Initiative (NWQI) aimed at reducing nutrients and sediment in the nation’s rivers and streams. The goal of the NWQI program is for the NRCS and its partners to work with landowners to implement voluntary conservation practices that improve water quality in high-priority watersheds while maintaining agricultural productivity. While high-priority watersheds have been selected around the country, typically watershed-scale evaluations identifying specific pollution sources and the conservation practices needed to improve water quality are not available to 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 NWQI 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 the Little Hunting Slough-Black River watershed located in Butler County in southeast Missouri. The project area is a 12-digit hydrologic unit code (HUC-12 #110100070805) watershed that is within the larger Upper Black River watershed. The watershed lies within the Mississippi River Alluvial Plain lowlands that were once a combination of swampy, bottomland forest and low sandy hills (Nigh and Schroeder 2002). After the timber was harvested in the early 1900s, the wetlands were drained and converted into highly productive cropland through the widespread construction of ditches and canals to move water off of the landscape (Marsden 1930, Graves 1983). With the exception of the protected publicly owned land and a few remnant wetlands, the majority of the land is cultivated for production of soybeans, rice, and corn (Nigh and Schroeder 2002, USDA 2016). While the lowland ditches in the Little Hunting Slough watershed are generally stable, they are considered poor aquatic habitat and typically lack an adequate riparian corridor (Cieslewicz 2004). The biggest water quality concern for the area is potential contamination of the shallow aquifer susceptible to agricultural chemicals, pesticides, and fertilizers that can pollute public and private water supplies (Miller and Vandike 1997). The purpose of this assessment is to provide NRCS field staff with the necessary information to identify locations within the Little Hunting Slough HUC-12 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 the 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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