A recent decision from the US District Court for the Eastern District of Virginia found that the Clean Water Act (CWA) does not authorize USEPA to regulate stormwater volume, or “flow,” as a surrogate measure for individual pollutants such as sediment contained in municipal stormwater runoff. The decision may cause difficulties for USEPA’s planned revisions to its municipal stormwater regulatory program, which have been

expected to focus on reducing stormwater pollution from areas of new development and redevelopment by setting restrictions for pollutants via a surrogate measure such as runoff volume or impervious surface area.

In April of 2011, USEPA established a Total Maximum Daily Load (TMDL) for a small tributary of the Potomac River located in Fairfax County, Virginia, which limited the allowable rate of stormwater runoff in the watershed to 681.8 cubic feet per acre-day.  The TMDL was designed to regulate the amount of sediment entering the creek, because USEPA believed that sediment was the primary cause of impairment to the biological community in the creek.  The Fairfax County Board of Supervisors and the Virginia Department of Transportation challenged USEPA’s action on the basis that USEPA did not have the statutory authority to regulate flow as a “surrogate” for the actual pollutant – sediment – that was causing the water quality impairment.

However, in its January 3, 2013 decision, the District Court held that “stormwater runoff is not a pollutant, so USEPA is not authorized to regulate it via a TMDL.”  The Court also noted that, although USEPA had previously issued thousands of TMDLs for sediment nationwide, it had tried the novel approach of regulating “flow” in only four instances—all of which were challenged in court.  This decision marks the first time a federal court has squarely addressed USEPA’s attempt to regulate stormwater volume directly under the CWA.

When USEPA developed its original “Phase I” municipal stormwater regulations in 1990, it included a requirement for large cities to develop controls to reduce the discharge of pollutants from storm sewers that receive discharges from areas of new development and redevelopment.  The “Phase II” regulations promulgated in 1999 required smaller cities to develop similar programs for new development or redevelopment projects covering one acre or more.  In “guidance,” USEPA suggested that such programs should “attempt to maintain pre-development runoff conditions” and “minimize impervious surfaces,” but the rule itself did not dictate any specific requirements, and the preamble recognized that “land use planning is within the authority of local governments.”

In 2006, however, USEPA asked the National Research Council (NRC) to conduct a comprehensive review of its stormwater program.  The final 2008 NRC Report found that the conversion of land to urban and suburban use and resulting alterations in stormwater flows had profoundly degraded water quality and habitat in urban streams.  The report suggested that, although the CWA ostensibly regulates only the discharge of “pollutants,” using increases in flow in urban watersheds as a “proxy” seems a “reasonable interpretation of the statute.”  Drawing upon the recommendations in the NRC Report, USEPA announced its intention to move forward with a nationwide rulemaking to address stormwater discharges from new development and redevelopment, stating that it planned to take “final action” on the new requirements no later than November 2012.

USEPA’s plans to change the focus of its municipal stormwater regulatory program drew extensive comments from the regulated community, many of which expressed concern about USEPA’s attempt to enact regulations that are not based on actual pollutant discharges, but on “surrogates”.  They pointed out that recent court decisions had made it clear that USEPA only has the authority to regulate “actual” discharges of pollutants from point sources, and not “potential” discharges. USEPA, itself, encountered difficulty in preparing a meaningful estimate of the

costs and benefits of its anticipated regulatory changes.  Given these difficulties, the agency was forced to extend its deadline for issuing the proposed and final regulations several times, with the proposed rule now expected by June 10, 2013 and final action by December 10, 2014.

Nevertheless, the potential impact of the new regulations is already clear in the municipal stormwater permit issued to the District of Columbia by EPA Region 3 on September 30, 2011.  Touted as being a model for other cities, the permit requires the District to ensure that all new development projects over 5,000 square feet will achieve on-site retention of 1.2” of rain from a 24-hour storm, and to establish a program to “retrofit” 18 million square feet (413 acres) of existing impervious surfaces over the 5-year permit term (including 1.5 million square feet located in transportation rights of way).  “Retrofit” is defined as improvement in a previously developed area that results in reduced stormwater discharge volumes and pollutant loads.

Similarly, USEPA’s new agenda was reflected in an informal guidance memorandum released in November 2010, which suggested that when state and federal permitting authorities are developing TMDLs and Wasteload Allocations (WLAs) for stormwater sources, “it may be suitable to establish a numeric target for a surrogate pollutant parameter, such as stormwater flow volume or impervious cover, that would be expected to attain water quality standards.” The memorandum also stated that, because it is “difficult” to identify a specific pollutant (or pollutants)

causing water quality impairments, using a surrogate parameter in developing WLAs for waters impaired by stormwater sources may be an “appropriate approach” for restoring such waterbodies.[7]

The District Court’s decision, however, throws the legal authority for this entire regulatory approach into doubt.  USEPA currently projects that its final rule will include some form of retention-based performance standard to reduce pollutant loads from the increased volume and velocity of stormwater discharges at newly developed and redeveloped sites, and that it may also include requirements for retrofiting of existing impervious surfaces.  This opinion, however, forcefully states that USEPA may not regulate something over which it has no statutorily granted power (nonpollutants) as a “proxy” for something over which it is granted power (pollutants).  Since the CWA prohibits only “the discharge of a pollutant,” and requires municipal stormwater permits “to reduce the discharge of pollutants,” USEPA’s plans to establish nationwide standards for reductions in stormwater flow or impervious surface area are certain to be challenged in the courts. It remains to be seen if USEPA will seek appellate review of this decision or attempt to find another legal rationale for its new regulatory program.