South Dakota Surface Water Quality

By Daniel Ostrem

Image from the 2014 Integrated Report from SD DENR.

South Dakota has about 9,726 miles of perennial rivers and streams and 86,660 miles of intermittent streams. The state also has about 572 lakes and reservoirs with designated aquatic life and recreational beneficial uses. Over the past five years (Oct 2008 - Sept 2013) the South Dakota Department of Environment and Natural Resources (DENR) has assessed these surface waters, as required under the Clean Water Act, and has found 94 different streams or stream segments and 72 lakes that are impaired, meaning that they don’t meet their intended beneficial uses.

The first step in addressing these impaired waters is to develop a Total Maximum Daily Load (TMDL) for the waterbody. A TMDL is a calculation to determine the sum allowable load of a pollutant from all contributing point (permitted municipal and industrial wastewater discharges) and non-point (agricultural and urban stormwater runoff) sources, that a waterbody can receive and still meet the applicable water quality standards (definition DENR). Waters differ in their intended beneficial uses depending on their source. Each beneficial use has a set of water quality criteria that go with it for that water to be considered as meeting its intended use. A stream that is a cold water fishery and has immersion recreation (swimming) will be held to a higher standard than a stream without those uses or criteria.

For example, to meet the water quality standards for immersion recreation, the water must meet these water quality criteria.

For example, to meet the water quality standards for immersion recreation, the water must meet these water quality criteria.

Other beneficial uses that the state considers are:

1. Domestic water supply waters;
2. Coldwater permanent fish life propagation waters;
3. Coldwater marginal fish life propagation waters;
4. Warmwater permanent fish life propagation waters;
5. Warmwater semipermanent fish life propagation waters;
6. Warmwater marginal fish life propagation waters;
7. Immersion recreation waters;
8. Limited contact recreation waters;
9. Fish and wildlife propagation, recreation, and stock watering waters;
10. Irrigation waters; and
11. Commerce and industry waters.

In order to attempt to reduce or maintain water quality to the standards, the DENR administers the National Pollutant Discharge Elimination System (NPDES) program. This program issues permits that limit point source discharges that are regulated under the Clean Water Act. Non-Point Source (NPS) pollution control is also addressed. However, since NPS pollution, which is usually caused by runoff, can be difficult to determine actual pollutant sources and amounts, a voluntary approach to encourage best management practices (BMPs) is being promoted. Section 319 of the Clean Water Act provides funding to the state for developing and implementing watershed restoration and BMPs to help lessen the pollutant loadings in runoff towards the water source of concern.

Some of these BMPs may include:

• Limiting livestock from stream access
• Animal waste management system
• Implementing conservation tillage practices on cropland
• Utilizing vegetative treatment systems such as constructed wetlands and buffer, or filter, strips
• Nutrient management planning
• Cover crops
• Installation of bioreactors and other conservation drainage practices for tiled areas

These programs are implemented by landowners and managers voluntarily, and in many cases, place extra management and cost burdens to these managers. Many conservation groups understand this and are working to help provide cost-share or other financial incentives to help increase the number of volunteers for BMP implementation.

Source:igrow.org