Ariz. Admin. Code § R18-11-210 - Site Specific Standards

A. The Director shall adopt a site-specific standard by rule.

B. The Director may adopt a site-specific standard based upon a request or upon the Director's initiative for any of the following reasons:

1. Local physical, chemical, or hydrological conditions of a non-WOTUS protected surface water such as pH, hardness, fate and transport, or temperature alters the biological availability or toxicity of a pollutant;

2. The sensitivity of resident aquatic organisms that occur in a non-WOTUS protected surface water to a pollutant differs from the sensitivity of the species used to derive the numeric water quality standards to protect aquatic life in R18-11-215;

3. Resident aquatic organisms that occur in a non-WOTUS protected surface water represent a narrower mix of species than those in the dataset used by ADEQ to derive numeric water quality standards to protect aquatic life in R18-11-215;

4. The natural background concentration of a pollutant is greater than the numeric water quality standard to protect aquatic life prescribed in R18-11-215 . "Natural background" means the concentration of a pollutant in a non-WOTUS protected surface water due only to non-anthropogenic sources; or

5. Other factors or combination of factors that upon review by the Director warrant changing a numeric water quality standard for a non-WOTUS protected surface water.

C. Site-specific standard by request. To request that the Director adopt a site-specific standard, a person must conduct a study to support the development of a site-specific standard using a scientifically defensible procedure. Before conducting the study, a person shall submit a study outline to the Director for approval that contains the following elements:

1. Identifies the pollutant;

2. Describes the reach's boundaries;

3. Describes the hydrologic regime of the waterbody;

4. Describes the scientifically defensible procedure, which can include relevant aquatic life studies, ecological studies, laboratory tests, biological translators, fate and transport models, and risk analyses;

5. Describes and compares the taxonomic composition, distribution and density of the aquatic biota within the reach to a reference reach and describes the basis of any major taxonomic differences;

6. Describes the pollutant's effect on the affected species or appropriate surrogate species and on the other designated uses listed for the reach;

7. Demonstrates that all designated uses are protected; and

8. A person seeking to develop a site-specific standard based on natural background may use statistical or modeling approaches to determine natural background concentration.

Notes

Ariz. Admin. Code § R18-11-210

Former Section R9-21-210 renumbered and amended as Section R9-21-211, former Section R9-21-209 renumbered and amended as Section R9-21-210 effective January 29, 1980 (Supp. 80-1). Amended subsection (A) effective April 17, 1984 (Supp. 84-2). Former Section R9-21-210 renumbered as Section R9-21-209, former Section R9-21-211 renumbered as Section R9-21-210 and amended effective January 7, 1985 (Supp. 85-1). Former Section R9-21-210 renumbered and amended as Section R9-21-211, former Section R9-21-209 renumbered and amended as Section R9-21-210 effective August 12, 1986 (Supp. 86-4). Former Section R9-21-210 renumbered without change as Section R18-11-210 (Supp. 87-3). Section repealed effective February 18, 1992 (Supp. 92-1). New Section made by final rulemaking at 29 A.A.R. 302, effective 2/20/2023.