South Dakota state law: stormwater management

SDCL 34A-2 is the South Dakota Water Pollution Control statute, authorizing DANR to administer the federal Clean Water Act NPDES program at the state level. The implementing rules sit in three Administrative Rules of South Dakota chapters: ARSD 74:51 (general water pollution control rules), ARSD 74:52 (Surface Water Discharge Permit Program, the NPDES-equivalent), and ARSD 74:54 (groundwater discharge). DANR's stormwater program documentation (danr.sd.gov/OfficeOfWater/SurfaceWaterQuality/stormwater) breaks coverage into four permit types:

1. CONSTRUCTION GENERAL PERMIT, required for any project that disturbs one (1) or more acres of land (including smaller projects that are part of a larger common plan of development). Operators must prepare a Stormwater Pollution Prevention Plan (SWPPP), implement best management practices (silt fence, sediment basins, stabilized construction entrances, inlet protection), conduct routine inspections, and file a Notice of Termination once final stabilization (70% perennial vegetative cover) is achieved.

2. INDUSTRIAL STORMWATER PERMIT, required for industrial facilities in SIC categories listed at 40 CFR 122.26(b)(14), covering manufacturing, salvage, transportation, mining, and similar.

3. MS4 PERMIT, required for any 'public entity such as a city or county with population/urbanized area of 10,000 or more people' (DANR program description). SD MS4 permittees include Sioux Falls, Rapid City, Aberdeen, Brookings, Watertown, and the urbanized portions of their host counties. Each MS4 must adopt and enforce six minimum control measures, including a local construction-site stormwater runoff control ordinance and a post-construction stormwater management ordinance.

4. TEMPORARY DISCHARGE PERMIT, for short-duration discharges to surface waters (dewatering, hydrostatic testing).

SD does NOT preempt stricter local stormwater rules. Cities and counties may adopt lower disturbance thresholds (e.g., 5,000 sq ft), broader BMP requirements, post-construction water-quality treatment minimums, and drainage/detention sizing standards under SDCL 9-29-1 (general welfare), SDCL Chapter 11-4 (municipal zoning), and SDCL Chapter 11-2 (county zoning). MS4 cities are effectively required to adopt local ordinances meeting EPA Phase II minimums.

Discharge without a required permit, or in violation of permit terms, is enforceable by DANR under SDCL 34A-2 with civil penalties up to $10,000 per day per violation plus injunctive relief, and may be prosecuted as a Class 1 misdemeanor (knowing violation). EPA retains overfiling authority under the federal Clean Water Act. Local MS4 ordinance violations carry city-set penalties (typically $100–$1,000 per day) and stop-work authority. Failure to file an SWPPP or maintain BMPs is the most common cited construction violation; DANR field inspectors can issue compliance orders requiring immediate corrective action.