5 Colo. Code Regs. § 1002-65.14
The provisions of sections 25-8-205 and 25-8-401, C.R.S., provide the specific statutory authority for adoption of the attached regulatory amendments. 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
The Commission affirms that the intent of Regulation 65 is to allow the Division to make a finding of violation where a discharge enters a storm sewer inlet or pipe based on the premise that such discharge will reach state waters, either directly or as a result of a subsequent storm or other unrelated flow event. The Commission finds that this authority is necessary above and beyond that provided to the Division under the Colorado Discharge Permit System Regulations, which would otherwise require the Division to demonstrate that the discharge reached state waters. The Commission does not intend that this action will alter the interpretation of the term "state waters." The Commission finds that it is appropriate to apply a more proactive regulatory approach due to the risk that such discharges could pose to the beneficial uses of state waters. In addition, the Commission finds that it is not appropriate to require the Division to expend what could be significant resources to monitor the outlet for potentially long periods before a subsequent storm or other flow event flushed the pollutants in the discharge into state waters. The Commission also states that this regulation does not authorize any storm water discharge that is otherwise required to obtain a permit pursuant to Regulation No. 61.
The Commission modified section 65.2 to delete the requirement for a discharger to have obtained a permit prior to discharge to a storm sewer and modified section 65.2 to provide that prohibition for discharge to a storm sewer does not apply where a permit has been obtained pursuant to section 25-8-501 C.R.S. This change was made to clarify that Regulation 65 does not require a permit for discharges to storm sewers but that the prohibition of such discharges does not apply where a permit has been obtained. The Commission adopted this change to avoid any potential conflict with the findings of a federal concentrated animal feeding operation permitting case (Waterkeeper Alliance v. EPA, 2nd Cir. 2005) which addressed a proposed provision in EPA's then-CAFO rule to require a permit of those who had the "potential" to discharge.
Section 65.2 was also modified to clarify that the regulation applies to discharges to infrastructure (storm sewer inlets and pipes).
The Commission established a new section 65.2 of the regulation to further address the provision regarding "pollutants in naturally occurring stormwater" that was previously in section 65.2 . The Commission clarified that the exception in section 65.2 applies only to pollutants that are incidentally deposited to the ground due to the use of that ground (e.g. fertilizer applied to landscape in accordance with package instructions, oil deposited by vehicles on a parking lot, magnesium chloride or other deicing agents properly applied to roads and other surfaces, etc.).
At the same time, the Commission also established a new section 65.2 to provide an opportunity for a person responsible for a discharge to demonstrate that the discharge did not reach state waters and that the pollutants were removed from the storm sewer such that there would be no risk of a subsequent flow event flushing them into state waters. This could be accomplished by cleaning of the storm sewer system to prevent later transmission of the spilled materials to waters of the state. The Commission finds this is appropriate, particularly for spills which may be of relatively short duration and of small volume. Colorado has a semi-arid climate, in which stormwater channels may be dry for significant portions of the year and stormwater systems are composed of impervious pipes and basins and present numerous opportunities to capture and detain spills, including curbside catch basins, detention basins, and flow diversion structures.
PARTIES TO THE RULEMAKING
5 CCR 1002-65.14