A new decision curtails agency discretion to approve total maximum daily loads for impaired waterbodies and sets a precedent that may lead to more stringent National Pollution Discharge Elimination System (NPDES) permit limits.
Total maximum daily loads (TMDLs) have been described as “pollution budgets” for impaired waterbodies. A permitting authority developing a TMDL typically considers all known sources of the pollutant at issue (including contributions from point and non-point sources) as well as the relevant characteristics of the waterbody (such as flow rates) and determines how much pollutant the waterbody can receive without exceeding applicable water quality standards. Once a TMDL is adopted for a specific pollutant that is adversely affecting a waterbody, the permitting authority (either a delegated state or EPA) will use the TMDL to derive NPDES permit limits for facilities that are sources of the pollutant.
In a strongly worded decision, the District Court for the District of Columbia, in part following earlier precedent, found that Congress intended EPA to set TMDLs that are actual maximum daily values, rather than constructs of averaged data. Anacostia Riverkeeper v. Wheeler, Slip Op. No. 16-cv-1651 (D.D.C. Aug. 12, 2019). Based on the language of the Clean Water Act and the precedent, the decision is not surprising. But it is a good example of a court sharply foreclosing agency discretion.
In 2014, EPA approved an E. coli TMDL proposed by the District of Columbia for portions of the Potomac and Anacostia Rivers. The Potomac River segment receives, among other inputs, the discharge from the Blue Plains sewage treatment plant. In 2015, the DC Water and Sewer Authority, which owns and operates Blue Plains, challenged the TMDL, claiming the allocations provided in the TMDL for the Blue Plains outfalls were too low. DC Water contended that EPA had used an average flow rate for the outfalls when it calculated the allocation and therefore the maximum load was less than what could be discharged without exceeding water quality standards.
After the lawsuit was filed, EPA withdrew its decision rationale for the TMDL and, in 2017, issued a revised rationale. Under the revised rationale, EPA acknowledged that the maximum daily value set for one of the Blue Plains outfalls was based on average flow rates for dry weather days, rather than the outfall’s permitted actual maximum flow rate. The revised rationale stated that the maximum daily load “is not intended—despite its label—to function as a ceiling or limits applicable to discharges… [b]ut represents an average of the daily maximum loadings expected to occur.” As the court interpreted this statement, “the figure did not represent the amount of pollutant that would enter the water on the highest-flow (and most pollutant-heavy) day, but the average amount that would enter the water on a given day.” Slip Op. at 7.
Environmental petitioners challenged the TMDL, in part arguing that EPA violated the Clean Water Act by approving a TMDL that failed to establish true maximum daily loads. The court, following Friends of the Earth v. EPA, 446 F. 3d 140 (D.C. Cir. 2006), found that the words “maximum” and “load” were individually unambiguous and also not ambiguous when combined in the phrase “total maximum daily load.” Slip Op. at 9-10. The court also rejected DC Water’s argument that the term was inherently ambiguous because the water quality standard that was the focus of the TMDL was a 30-day geometric mean standard, not a daily standard: “Nothing about a 30-day average precludes the setting of a daily maximum. As a purely mathematical matter, there must be a daily discharge that, if exceeded, would cause the concentration of E. coli to spike so high that the 30-day mean could not be achieved, even if the other daily discharges were minimal. That is the maximum load. The court sees no ambiguity here.” Id. at 10.
The court also rejected EPA’s argument that, even if “total maximum daily load” is unambiguous, the maximum load need not be expressed in a fixed term, but can vary, so long as the 30-day geometric mean standard is being met. As the court explained: “The bottom line is that EPA’s interpretation does not comply with the statutory mandate. The statute’s unambiguous text requires EPA to approve figures that represent upper limits of pollutants that can enter water bodies on any given day. Those figures must be sufficiently low to ensure that, when complied with, the water quality standards are met. This is a two-step process. First, the TMDLs must be established; second, they must achieve the water quality standards. It is not a permissible interpretation of the statute to fold the first step into the second and approve TMDLs that do not articulate known maximums.” Slip Op. at 13-14.
Additionally, environmental petitioners claimed EPA’s approval violated the Clean Water Act because the TMDL failed to meet two applicable narrative water quality criteria, which required that surface waters be “free from substances” injurious or toxic to humans and free from untreated sewage discharges constituting “a hazard to the users” of the waterbody. EPA argued that implementation of the numeric water quality standards through the TMDL would necessarily mean that the narrative criteria would be attained. But the court emphasized that narrative criteria are a “distinct set of standards that must also be achieved to maintain designated uses” of the waterbody. Slip Op. at 26. While the court found some evidence in the record which suggested the narrative criteria might be satisfied, it sided with environmental petitioners, finding the record not well developed on this issue. Id. at 28.
The influential District and Circuit Courts of the District of Columbia are strictly interpreting “total maximum daily load.” As a result, we can expect to see more stringent TMDLs and, eventually, more stringent permits derived in light of those TMDLs. As always, it is important to monitor state and federal action to devise TMDLs, since TMDLs will drive permit limits. It is best to be involved very early in the TMDL development process if you have a facility on an affected waterbody.