Wet Weather NPDES Permitting (Including SSOs): Case Studies from Around the Country

Wet weather discharges are often cited as being a cause of (or contributing to) water bodies not attaining water quality standards. Wet weather discharges include stormwater systems, combined sewer overflows (CSOs), sanitary sewer overflows (SSOs), and nonpoint sources. All of these sources except for nonpoint sources require a National Pollutant Discharge Elimination System (NPDES) permit in order to discharge pollutants. A strategy for managing these diverse sources is needed.The difficulty associated with effectively addressing wet weather discharges under the NPDES permit program is not a new issue; however there are a number of examples from different parts of the country that provide some innovative and thought provoking ideas for possible solutions. SSOs are point source discharges; however the ability to include SSOs in NPDES permits is one impediment to a fully operational and integrated approach to wet weather permits that is shared across the country. In many states, the discharges from SSOs are considered to be “prohibited” without any regulatory basis provided for this blanket prohibition. This problem of lack of regulatory basis is often magnified by federal enforcement actions and consent decrees that require the “elimination” of SSOs without any mechanism for achieving the requirement.In 1999, EPA published a draft proposed regulation to provide a strategy for addressing SSOs, but the regulation never went forward. In the draft document, EPA acknowledged that eliminating SSOs was not possible. Despite this recognition, very few states have developed a strategy for addressing SSOs. The CWA does not prohibit issuing NPDES permits for the discharge from a SSO. This raises several important questions. Why aren't SSOs currently being included in municipal NPDES permits? What are the impediments to issuing NPDES permits for SSO discharges? How do we overcome these impediments and move forward?In 2004, NACWA (at the time AMSA) published a White Paper: Sanitary Sewer Overflows Legal Issues. This White Paper looked at the issue of how to control overflows from a theoretical legal perspective. The paper provided a number of recommendations for EPA to consider regarding the permitting of SSOs.On April 30, 2010, Water Environment Federation (WEF) adopted a position statement: “Management of Wet Weather Flows by Municipal Utilities”. This position statement highlighted many of the issues municipal systems face and recommended that EPA should “develop a strategy and guidance for integration of municipal wet weather programs that will assist permitting authorities with design and implementation of permits to address the unique nature of wet weather discharges and the controls necessary to achieve water quality goals. The strategy and guidance will enable permitting authorities to utilize flexibility available in the NPDES permit program to focus on water quality goals. The strategy and guidance will also encourage urban areas to develop their wet weather programs in a comprehensive manner following the WEF Guide that organizes NPDES information and planning to help decision makers prioritize wet weather control programs”.All of these efforts represent attempts to establish a system to manage wet weather flows in the existing regulatory framework. The following sections will review some of these efforts, the existing regulations and policies in place, as well efforts by states to provide a permit framework for addressing wet weather flows. The states of North Carolina, California, Wisconsin and South Carolina have each developed a general permit to address discharges from collection systems. These will be discussed as examples of current approaches to control wet weather discharges.