Over the past few decades, the United States Environmental Protection Agency (USEPA) has often exercised its authority under the Clean Water Act (CWA) to regulate and manage wastewater and industrial discharges. However, how to properly manage stormwater runoff has remained an open and contentious issue amongst the agency, industry, and environmental groups. Stormwater runoff, and more specifically the pollutants carried in the runoff, is a major contributor to water quality issues across the country.

Just last month, USEPA addressed several proposed rules, regulations, and petitions related to stormwater. First, the agency removed numeric turbidity limits from the CWA construction stormwater rule; second, the agency declined several environmental groups’ petitions to use its Residual Designation Authority to develop stormwater permitting programs; and finally, it deferred establishing a national post-construction stormwater rule. This Advisory discusses these agency decisions in more detail below.


As a result of a December 2012 settlement with industry groups, USEPA recently revised the CWA construction stormwater rule to eliminate numeric effluent limits on turbidity and the related monitoring requirements. Turbidity, a key test of water quality, is a measure of how much material, such as soil particles (clay, silt, and sand), algae, plankton, microbes, and other substances, is suspended in water and how much the material reduces the passage of light through the water.

This revision is the culmination of a lengthy rule-making process. USEPA first proposed effluent guidelines for stormwater discharges associated with the construction and development category in 2002, but never finalized the rule. The agency was later sued by several environmental groups in the Ninth Circuit Court of Appeals. The court compelled the agency to issue a proposed rule by December 1, 2008 and a final rule by December 1, 2009. After consideration of significant comments, the agency finalized the rule on December 1, 2009 establishing a numeric turbidity limit of 280 nephelmetric units (NTUs). The rule also imposed requirements to implement a range of erosion and sediment controls and pollution prevention measures at construction sites.

Industry groups, including the National Association of Homebuilders and the Utility Water Act Group, immediately challenged the 2009 rule in court. In addition, the U.S. Small Business Administration petitioned USEPA to reconsider, alleging that the numeric turbidity limit was too costly to small businesses and that the agency misinterpreted the data it used to establish the numeric limits.

In December 2012, USEPA settled with the industry groups, agreeing to withdraw the numeric turbidity limit and to accept public comment on certain changes to the non-numeric requirements of the 2009 rule regarding best practicable control technology currently available (BPT) to reduce pollution from stormwater; effluent limitations reflecting the best conventional pollutant control technology (BCT); and new source performance standards (NSPS). The new rule was finalized on March 6, 2014. 79 Fed. Reg. 12661.

Also, in 2012, USEPA replaced its 2008 Construction General Permit (CGP) with a new version based on the 2009 rule, but which excluded a numeric limit on turbidity. Unlike individual permits, a general permit has standardized terms, authorizing anyone who meets its requirements to engage in a regulated activity. The CGP applies in states where USEPA is the CWA permitting authority, including Massachusetts, New Hampshire, Idaho, and New Mexico, as well as in the District of Columbia, most U.S. Territories, and Indian lands. The remaining states, which have been delegated authority by USEPA to implement the CWA, may issue their own general permits since they are not bound to follow USEPA’s CGP. Thus, due to the uncertainty surrounding numeric turbidity limits, these “delegated states” may have included such numeric limits in their general permits. Permit holders should ensure that they understand the obligations under their existing permits. Our prior Advisory explaining the differences in the 2008 and 2012 CGP can be found here.


In July 2013, the Natural Resources Defense Council, American Rivers, and the Conservation Law Foundation all filed petitions with USEPA Regions 1, 3, and 9 seeking a determination that stormwater discharges from commercial, industrial, and institutional (CII) sites contribute to violations of water quality standards. The NGOs urged USEPA to use its Residual Designation Authority (RDA) under 40 C.F.R. §122.26(a)(9)(i)(D) to develop a stormwater permitting program that would require National Pollutant Discharge Elimination System (NPDES) permits for current unregulated non-de minimis stormwater discharges from CII sites.

The RDA allows USEPA to designate a category of discharges, within a geographic area, if the agency determines that the discharges contribute to a violation of a water quality standard or significantly contribute pollutants to the waters of the United States. Any discharge or category of discharges designated under RDA is subject to NPDES permitting requirements.

The petitions cited a number of pollutants of concern, including lead, copper, zinc, total suspended solids (TSS), Biochemcial Oxygen Demand (BOD)/Chemical Oxygen Demand (COD), and nutrients (phosphorus and nitrogen), that contribute to impairment of water bodies in the particular Region. The petitions further claimed that impervious surfaces at CII sites are contributing to violations of the water quality standards.

Regions 3 and 9 denied the petitions, citing an insufficiency of data on which to base a categorical designation. Although Region 1 also found the present data to be insufficient, it neither granted nor denied the petition. Instead, the Region stated that “it intends to evaluate watersheds, focusing on the nature of the impairment and the extent to which stormwater discharges from CII sites are contributing to such impairment, to determine whether and the extent to which exercise of RDA is appropriate.” Region 1 also stated that it will consider Region-specific data that were not provided or cited by the petitioners that directly connects a CII site or category to a specific impairment.

This is not new territory for Region 1. It has used its RDA before. For example, in 2009 the Region designated Long Creek in Maine and has proposed certain stormwater discharges in three communities on the Charles River in Massachusetts for designation. Since this latter designation has not been finalized, the Region plans to reevaluate a separate petition previously filed by the Conservation Law Foundation, and consider expanding the designation to cover additional Massachusetts towns or the entire Charles River watershed.


USEPA has grappled with the question of whether to implement a national stormwater rule regulating discharges from newly developed and redeveloped sites. Advocates for such a program have sought a rule with flexibility to account for local and state variation. It is this variation in region, geography, and climate, however, that opponents of such a rule say would make national uniform performance standards difficult to establish and implement.

The time for USEPA to consider this question recently expired under a 2010 settlement agreement that had resolved litigation by the Chesapeake Bay Foundation. Despite the deadline in the settlement agreement, on March 19, the agency stated that it would defer any action on a national rule to address post-construction stormwater from newly built and redeveloped sites. Instead, USEPA will focus on localized solutions, providing incentives, technical assistance, and other tools to help communities address stormwater runoff themselves. This solution may prove difficult to implement too, considering that most municipalities have limited budgets for stormwater infrastructure management and maintenance.