5 Colo. Code Regs. § 1002-31.46
The provisions of sections 25-8-202(1)(b), 25-8-204; and 25-8-402, C.R.S., provide the specific statutory authority for adoption. The Commission also adopted, in compliance with section 24-4-103(4) C.R.S., the following statement of basis and purpose.
BASIS AND PURPOSE:
In this rulemaking, the Commission adopted revised and new organic chemical standards in section 31.11 . In an effort to keep ground water and surface water organic chemical standards consistent, the changes to 31.11 were considered during the same hearing that addressed changes to the statewide Ground Water Organic Chemical Standards in Regulation No. 41 (Basic Standards for Ground Water).
In adopting these new and revised organic chemical standards, the Commission continued to rely on its past policy decisions and precedence documented in Commission Policy 96-2. Additionally, as per Departmental policy the Commission has relied on the United States Environmental Protection Agency's (EPA) Integrated Risk Information System (IRIS) as its first tier source of toxicological data. Review of the IRIS data that had been updated since the last revisions to section 31.11 indicated that the water quality standards for two organic chemicals, toluene and 1,2-dibromoethane, needed to be revised.
At the last hearing addressing section 31.11(3), in September 2004, during which the Commission adopted water quality standards for several carcinogenic compounds, EPA had requested that a future rulemaking consider water quality standards for non-carcinogenic compounds. For this hearing the Commission reviewed several non-carcinogenic compounds that lacked water quality standards. This review identified four pesticides for which the Commission elected to adopt water quality standards: acetochlor, dicamba, metribuzin, and prometon. Aquatic life-based standards for diazinon were also adopted, based on EPA guidance.
Nonylphenol: The Commission considered evidence presented in regards to the proposal to adopt aquatic life-based standards for nonylphenol. The Commission decided to adopt acute and chronic standards with a delayed effect date of 7/1/2010 as agreed to by the parties and the Division. This delay is intended to allow time for EPA, the Division and the parties to resolve uncertainty regarding the analytical methods for testing influent waste streams. Prior to the effective date, the Metro Wastewater Reclamation District, the City of Boulder, Littleton/Englewood and Colorado Springs Utilities have committed to working on source control of nonlyphenol with the commercial laundry sector through their Pretreatment Programs. For purposes of discharge permits, the Commission expects that, because of limitations in the available data, the Division will include effluent monitoring requirements in major permits issued prior to the delayed effective date. The monitoring requirement would become effective the same date that the standards became effective.
The Commission also corrected several typographical errors and added common synonyms for some of the organic chemicals.
PARTIES TO THE RULEMAKING
5 CCR 1002-31.46