The 1996 amendments to the Safe Drinking Water Act require all community water systems to perform a source water assessment. A source water assessment is a three step process that includes determining the land area that contributes water to a water supply, identifying the significant potential sources of contamination to the water supply within that area, and determining the water supply's susceptibility to contamination from those identified sources. The South Dakota Department of Environment and Natural Resources (SDDENR) is responsible for completing the source water assessments for each of the 750 community water supplies in South Dakota. The Source Water Assessment for the City of Sioux Falls was completed in 2003.
The city currently utilizes the Big Sioux River, the Big Sioux Aquifer, the Middle Skunk Creek Aquifer, the Split Rock Creek Aquifer, and the Lower Skunk Creek Aquifer to provide water for the City. Based on the findings of this report, these sources are moderately susceptible to contamination. The City continually monitors its source waters for contamination and has a long history of providing safe drinking water to our customers. You may view a copy of the report at the offices of the SDDENR in Pierre or at the Sioux Falls Water Purification Plant.
Central Big Sioux River Watershed Assessment
The East Dakota Water Development District (Brookings, SD) has received a grant from the South Dakota Department of Environment and Natural Resources (SDDENR) and the United States Environmental Protection Agency (USEPA) to perform an assessment of the central portion of the Big Sioux River watershed. The purpose of this assessment is to determine the sources of impairment and develop restoration alternatives for the central portion of the Big Sioux River (BSR) (between the communities of Volga and Sioux Falls) and major tributaries in Brookings, Lake, Moody, and Minnehaha counties of South Dakota.
Direct runoffs to the river, as well as permanent and intermittent tributaries, contribute loadings of sediment, nutrients, and fecal coliform bacteria primarily related to seasonal snow melt or rainfall events. In the 1998 and 2000 South Dakota Report to Congress 305(b) Water Quality Assessment and the 1998 and 2002 South Dakota 303(d) Waterbody List, the central portion of the Big Sioux River, as targeted in this project, is listed as only partially supporting or not supporting the designated uses. Total suspended solids (TSS) are the primary problem in the northern portion of this segment between the communities of Brookings and Dell Rapids. From Dell Rapids to Brandon, and including the city of Sioux Falls, excessive fecal coliform bacteria and total suspended solids are the major problems. Through water quality monitoring (chemical and biological), stream gauging, and land use analysis, sources of impairment can be determined and feasible alternatives for restoration efforts can be developed.
The 1998 and 2002 South Dakota 303(d) Waterbody List identifies this portion of the river as a priority for the development of Total Maximum Daily Loads (TMDL's) of the pollutants of concern. This final TMDL assessment report will serve as the foundation for restoration projects that can be developed and implemented to meet the designated uses and water quality standards of the central BSR and its tributaries. This project is intended to be the initial phase of a series of watershed-wide restoration implementation projects.
Goals
The goals of this assessment project are to:
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Determine and document sources of impairments to the central portion of the BSR watershed in eastern South Dakota.
- Identify feasible restoration alternatives to support watershed implementation projects to improve water quality impairments within the watershed.
- Develop TMDL based on identified pollutants.
Impairments cited in the 1998 and the 2000 305(b) Water Quality Assessment Report and the 1998 and 2002 South Dakota 303(d) Waterbody List for this portion of the BSR watershed are excessive pathogens (fecal coliform bacteria) and suspended solids.
Goals were accomplished through the collection of tributary and river data and aided by the completion of the FLUX, Sediment Delivery Model (SDM), and the Agricultural Nonpoint Source (AGNPS) watershed modeling tools. Through data analysis and modeling, the identification of impairment sources was possible. The identification of these impairment sources will aid the state’s Nonpoint Source (NPS) program by allowing strategic targeting of funds to portions of the watershed that will provide the greatest benefit per expenditure.
This project is in its final stages with the draft of the final report being distributed for comments. It is anticipated that the report will be finalized this year (2005). Grant proposals will also be written to secure funds to begin implementing best management practices that target those areas identified as impairment sources within the report.
