Terms used in this chapter mean:

1. (1) "Adverse impact on visibility," visibility impairment that interferes with the management, protection, preservation, or enjoyment of the visitor's visual experience of the mandatory Class I federal area;
2. (2) "BART," best available retrofit technology;
3. (3) "Best available retrofit technology," an emission limitation based on the degree of reduction achievable through the application of the best system of continuous emission reduction for each pollutant that is emitted by an existing stationary facility;
4. (4) "BART-eligible source," an existing stationary facility;
5. (5) "Coal-fired power plant," any person, corporation, limited liability company, association, company, partnership, political subdivision, municipality, rural electric cooperative, consumers power district, or any group or combination acting as a unit, owning or holding under lease or otherwise, real property used, or intended for use, for the conversion of coal into electric power;
6. (6) "Contribute to adverse impact on visibility," a change in visibility impairment in a mandatory Class I federal area of five-tenths deciviews or more, based on a twenty-four-hour average, above the average natural visibility baseline;
7. (7) "Major source," as defined in subdivisions 74:36:01:08(2) and (3);
8. (8) "Mandatory Class I federal area," any area identified in 40 C.F.R. Part 81, Subpart D (July 1, 2024);
9. (9) "Visibility impairment," any human-perceptible change in visibility such as light extinction, visual range, contrast, coloration, from that which would have existed under natural conditions;
10. (10) "Thirty-day rolling average," an amount expressed as pounds per million Btus and pounds per hour averaged over thirty operating days; and
11. (11) "Operating day," a twenty-four-hour period between midnight and the following midnight during which any fuel is combusted at any time in the period, even if fuel is not combusted during the entire twenty-four-hour period.

Source: 37 SDR 111, effective December 7, 2010; 38 SDR 39, effective September 19, 2011; 39 SDR 219, effective June 25, 2013; 42 SDR 52, effective October 13, 2015; 44 SDR 43, effective September 13, 2017; 46 SDR 64, effective November 25, 2019 ; 52 SDR 27, effective September 17, 2025 .

General Authority: SDCL 34A-1-6 .

Law Implemented: SDCL 34A-1- 1 .

Prior versions effective: 2019-11-25, 2017-09-13, 2015-10-13, 2013-06-25.