5 Colo. Code Regs. § 1002-32.57
The provisions of C.R S. 25-8-202(1)(a), (b) and (2); 25-8-203; 25-8-204; and 25-8-402; provide the specific statutory authority for adoption of these regulatory amendments. The Commission also adopted in compliance with 24-4-103(4) C.R.S. the following statement of basis and purpose.
BASIS AND PURPOSE
In 2010, the Commission adopted the discharger specific variance (DSV) provisions at Regulation 31.7(4), which allow a temporary water quality standard to be adopted in cases where water quality based effluent limits (WQBELs) are not feasible to achieve. A DSV is a hybrid standard that maintains the long-term water quality goal of fully protecting all designated uses, while temporarily authorizing an alternative effluent limit (AEL) to be developed for a specific pollutant and specific point source discharge where compliance with the WQBEL is not feasible.
Pursuant to 40 CFR 131.14(b)(1)(v)-(vi), the Commission must re-evaluate every DSV with a duration longer than five years and provide EPA notice of the results within 30 days of the completion of the re-evaluation process. If the Commission does not complete this action, the federal regulation states that the DSV will no longer be the applicable water quality standard for purposes of the Clean Water Act. This re-evaluation is consistent with Commission Regulation 31.7(4), which requires that the Commission re-examine all DSVs not less than once every three years. For purposes of EPA's notice requirement, the Commission's re-evaluation can be completed at two different points:
The Commission adopted a DSV for Lower Arkansas River Segment 1b for selenium that represents the highest degree of protection of the classified use that is feasible for the City of La Junta. For selenium, effluent limits for the City of La Junta shall not be more restrictive than a load-based effluent limit of 0.37 pounds per day as a 12-month rolling average prior to 12/31/2026. The Commission determined that in La Junta's site-specific circumstances, a 12-month rolling average loading limit would be the most effective way to measure progress in feasible selenium reduction. The Commission determined not to adopt a daily maximum alternative effluent limit at this time, because the feasible improvements are expected to reduce average loading. Daily fluctuations in selenium levels may be outside of the discharger's control at this time, therefore, an acute limit would not be an appropriate regulatory mechanism to determine whether implementation of the selected alternatives were successful.
La Junta submitted evidence that meeting the selenium WQBEL would cause substantial and widespread adverse social and economic impacts in the area where the discharge is located. Alternatives that would allow La Junta to meet the selenium WQBEL, such as disposal of wastewater via an injection well, would result in user fees that exceed the community's ability to pay. The Commission determined that the threshold for substantial and widespread social and economic impacts would be user fees exceeding 1.0% of median household income for La Junta's residents due to the current economic hardship in La Junta, including relatively high unemployment, a large existing debt burden, 26% of La Junta's citizens living in poverty and a local median household income that is significantly lower than the State's average. Since wastewater user fees currently exceed 1.0% of median household income, no additional capital investment in selenium treatment is economically feasible at this time.
The Commission determined that some reduction in selenium loading may currently be feasible through a Pollutant Minimization Plan that incorporates low-cost or no-cost operational changes. However, since it is difficult to predict or quantify how much improvement is feasible, at this time, the Commission is adopting an alternative effluent limit at the current condition. Also, there is uncertainty in characterizing the current condition, because La Junta's selenium loading is largely related to the city's water demand, which varies annually due to climate variability. The last 10 years of effluent data may not represent the longer-term current condition regarding water demand or selenium loading. Furthermore, the concentration of selenium in La Junta's source water is outside of La Junta's control and could improve or worsen over time. These uncertainties may be addressed during future re-evaluations.
La Junta will collect additional data to reduce the uncertainty when re-evaluating the AEL at future hearings. Over the next several years, monitoring frequency will be increased and will include internal monitoring locations to characterize the variability of selenium concentrations in the source water and in the reverse osmosis wastewater stream, as well as the domestic WWTF influent and effluent. La Junta will implement a Selenium Pollution Minimization Plan including water conservation, increasing efficiency in the water treatment plant, and piloting treatment of the reserve osmosis concentrate utilizing the new wastewater treatment plant. Since the basis for this DSV is economic feasibility, at future re-evaluations of the DSV, the Commission will review whether economic conditions have changed in a way that would make additional reductions in selenium feasible.
The Commission will conduct a re-evaluation of the DSV during the triennial review process for this regulation. At the time of the issues scoping hearing and the issues formulation hearing for this regulation, the Division will review all existing and readily available information and provide comments to the Commission regarding whether the DSV continues to be the highest attainable condition. The Commission also expects that La Junta will submit a progress report for the Commission's review of the DSV and the AEL during the June 2018 Arkansas River Basin rulemaking hearing. The Commission will obtain public input on the re-evaluation through the triennial review process. For purposes of EPA's notice requirement, the Commission's re-examination of this DSV will be completed at the effective date of the 2018 and 2023 Arkansas River Basin rulemaking hearings, and the Commission will submit the results of the re-evaluation to EPA no later than 30 days after the effective date of the rulemaking. The requirements of the DSV will either remain at the AEL identified at the time of the adoption of the variance, or be modified to the highest attainable condition identified during any re-evaluation rulemaking hearing held by the Commission.
Due to the remaining uncertainty in the underlying standard on Lower Arkansas River Segment 1b, the Commission directs the Water Quality Control Division to work with interested parties to collect selenium fish tissue data and further investigate the selenium criteria necessary to protect aquatic life.
PARTIES TO THE RULEMAKING HEARING
5 CCR 1002-32.57