The Vermillion River Total Maximum Daily Load (TMDL) Watershed Assessment Project is a multifaceted, multi-agency effort consisting of the collection and analysis of chemical, physical, biological and land use data. The assessment will include two years of extensive field data collection and one year of data analysis, report writing, and TMDL development. This is a cooperative effort amongst the Vermillion Basin Water Development District (VBWDD), South Dakota Department of Environment and Natural Resources (DENR), EPA Region VIII, local conservation districts, and county governments.
The Vermillion River watershed is the one of the most impaired watershed in South Dakota having 12 stream segments and three lakes (Silver, Thompson, and East Vermillion) on the South Dakota 2002 303(d) list. These waterbodies are impaired because they do not meet the minimum water quality standards for beneficial uses such drinking water, swimming, fishing, and irrigation. The impairments found in the watershed include ammonia, phosphorus, total suspended solids, dissolved oxygen, fecal coliform bacteria, and pH.
"Water quality is important to all of our daily lives," said DENR Secretary Steve Pirner. "DENR will work with the Vermillion Basin Water Development District to identify problem areas in the Vermillion River watershed and determine what steps should be taken if water quality is to be maintained or restored."
A TMDL report specifies the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards. This includes allocating pollutant loadings among point and nonpoint pollutant sources.
The Vermillion River watershed is located within eleven counties of southeastern South Dakota (Figure 1). It drains 1.43 million acres from Lake Thompson to the confluence with the Missouri River near the town of Vermillion (Figure 2).
The goals of this project are to 1) determine and document sources of impairments to the Vermillion River watershed through data collection, 2) develop TMDLs, and 3) identify feasible restoration alternatives to support implementation project(s) to improve water quality within the watershed.
1. Water Quality Monitoring
Water quality samples collected from the gauging sites using EPA approved methods will be used to quantify sediment loading and determine the chemical condition of the river (Figure 3). The samples will be collected during storm events and baseflow conditions each spring, summer, fall, and winter to see how the quality of the water changes throughout the year.
Instruments have been placed in the Vermillion River and selected tributaries to maintain a continuous record of water levels in the channels (Figure 4).
Discrete flow measurements are collected during high and low flows periods to develop a record of discharges in the watershed (Figure
In-stream habitat and riparian data will be collected along with aquatic macroinvertebrates and fishes. This information will be used to determine which areas are least impacted within the watershed. Areas that are classified as least-impacted could be used to help set achievable water quality goals for impacted locations in the watershed.
The landuse data consisting of cropping rotations, fertilization rates, tillage practices, animal feeding operations, and urban area impacts (Figure 7) will be modeled with the annualized version of Agricultural Non-Point Source Pollution Model (AnnAGNPS). This model, used in conjunction with the hydrology and water quality monitoring, will be used to identify critical areas within the watershed.
Each state is required by EPA through Section 303(d) of the Clean Water Act to prepare a list of waterbodies not meeting water quality standards. This project was created because there are 15 impairments in the Vermillion River watershed. The TMDL report will quantify the maximum level of pollutants allowable in each segment of the Vermillion Watershed. This report will be a tool used in future restoration projects to improve water quality in the Vermillion River watershed.
