Ind. Admin. Code tit. 327, r. 2-1.3-3 – Antidegradation standards

Authority: IC 13-13-5-1; IC 13-13-5-2; IC 13-18

Sec. 3. (a) The Tier 1 antidegradation standard is as follows:

(1) For all surface waters of the state, existing uses and the level of water quality necessary to protect existing uses shall be maintained and protected. To ensure this standard is met, the commissioner shall do the following:
1. (A) Ensure that the level of water quality necessary to protect existing uses is maintained. In order to achieve this requirement, water quality standards use designations must include all existing uses.
2. (B) Establish controls as necessary on nonpoint sources, where authority exists, and point sources of regulated pollutants to ensure the following:
  1. (i) The criteria applicable to the designated use are achieved in the water.
  2. (ii) Any designated use of a downstream water is maintained and protected.
(2) Where designated uses of waters are impaired:
1. (A) there shall be no additional lowering of the water quality with respect to the regulated pollutants that are causing the impairment; and
2. (B) to ensure the standard under clause (A) is met, the commissioner shall not allow a lowering of water quality for the regulated pollutants that prevents the attainment of the:
  1. (i) designated use; or
  2. (ii) water quality criterion.

(b) The Tier 2 antidegradation standard for HQWs that are not ONRWs or OSRWs is as follows:

(1) The surface waters of the state where existing quality for a parameter is better than the water quality criterion for that parameter established in 327 IAC 2-1-6 or 327 IAC 2-1.5-8 shall be considered high quality for that parameter.
(2) This high quality of water for a parameter shall be maintained and protected unless the commissioner finds, after full satisfaction of intergovernmental coordination and public participation and the provisions in section 5 of this rule, that allowing a significant lowering of water quality is necessary and accommodates important social or economic development in the area in which the waters are located. In allowing a significant lowering of water quality, the commissioner shall assure the following:
1. (A) Water quality adequate to fully protect existing uses is maintained.
2. (B) The highest statutory and regulatory requirements for all new and existing point sources are applied.
3. (C) Where authority exists, all cost-effective and reasonable BMPs for nonpoint source control are employed.

(1) For OSRWs inside the Great Lakes basin, no new or increased loading of a BCC, except mercury, shall be allowed that causes a significant lowering of water quality of the OSRW.
(2) For mercury in OSRWs inside the Great Lakes basin, BCCs in OSRWs outside the Great Lakes basin, and non-BCCs in all OSRWs, the following apply:
1. (A) These waters shall be maintained and protected in their present high quality unless the commissioner finds, after full satisfaction of:
  1. (i) intergovernmental coordination and public participation; and
  2. (ii) the provisions in sections 5 and 7 of this rule;
2. that allowing a significant lowering of water quality is necessary and accommodates important social or economic development in the area in which the waters are located.
3. (B) In allowing a significant lowering of water quality, the commissioner shall assure the following:
  1. (i) Water quality adequate to fully protect existing uses is maintained.
  2. (ii) The highest statutory and regulatory requirements for all new and existing point sources are applied.
  3. (iii) Where authority exists, all cost-effective and reasonable BMPs for nonpoint source control are employed.
(3) For OSRWs, any new or increased loading of a regulated pollutant that results in a significant lowering of water quality for that regulated pollutant shall be prohibited, unless the:
1. (A) activity causing the increased loading:
  1. (i) results in an overall improvement in water quality in the OSRW; and
  2. (ii) meets the applicable requirements of this section; or
2. (B) person proposing the increased loading implements or funds a water quality improvement project in accordance with IC 13-18-3-2 in the watershed of the OSRW that:
  1. (i) results in an overall improvement in water quality in the OSRW; and
  2. (ii) meets the applicable requirements of this section.

(d) In addition to the OSRWs designated under IC 13-18-3-2(u) or listed at 327 IAC 2-1.5-19(b), the following waters are designated by the board to be OSRWs:

(1) The Blue River in Washington, Crawford, and Harrison counties, from river mile 57.0 to river mile 11.5.
(2) The North Fork of Wildcat Creek in Carroll and Tippecanoe counties, from river mile 43.11 to river mile 4.82.
(3) The South Fork of Wildcat Creek in Tippecanoe County, from river mile 10.21 to river mile 0.00.

(e) The Tier 3 antidegradation standard for HQWs that are ONRWs is the following:

(1) These waters shall be maintained and protected in their present high quality without degradation except for short-term, temporary loadings as described in section 4(a) of this rule.
(2) To ensure the antidegradation standard under subdivision (1) is met, the following requirements apply:
1. (A) A deliberate activity that:
  1. (i) is not exempt under section 4 of this rule; and
  2. (ii) results in a new or increased loading;
2. is prohibited.
3. (B) A loading to a tributary of an ONRW that is not exempt under section 4 of this rule shall not be allowed if it would cause an increase in the ambient concentration of that pollutant in the ONRW.

(f) Except for ONRWs, any determination made by the commissioner in accordance with Section 316 of the CWA concerning alternative thermal effluent limitations shall be considered to be consistent with the antidegradation standards contained in this section.

(Water Pollution Control Division; 327 IAC 2-1.3-3; filed May 29, 2012, 3:19 p.m.: 20120627-IR-327080764FRA; readopted filed Oct 18, 2024, 1:57 p.m.: 20241113-IR-327230810RFA)