The emergence of green infrastructure concepts
Green infrastructure ideas preceded the widespread use of the term. Wetlands and coastal zone regulations, species conservation plans, water supply protections, and land trust agreements have long invoked the importance of intact natural systems in filtering pollutants, providing habitat for fish and wildlife, pollinating crops, and shielding human communities from storm surges and flooding. The “ecosystem services” literature in recent decades has elaborated on the many important societal benefits of healthy ecosystems that often go unrecognized in economic terms. Proponents of protections for ecosystem services argue that society should find better ways to invest in ecosystem functions, just as ratepayers fund the operations of public utilities that provide public services, such as sewage treatment and water supply.
The emergence of green infrastructure as a key component of urban stormwater and wastewater management reflects advances in efforts to coordinate the human uses of built environments with ecosystem dynamics. While the ecosystem services literature emphasizes the self-organizing capacities of nonhuman organisms in a habitat, often at a regional or watershed scale, green infrastructure projects in an urban setting typically seek to mimic natural hydrological functions through careful local planning and design of management measures and technologies. These projects make use of soil and vegetation but often rely significantly on human intervention, not only for initial engineering but also for ongoing operations and maintenance. For example, they may incorporate permeable pavements and rain barrels within a landscape design that also includes vegetated swales and bioretention facilities.
By facilitating stormwater management through innovative landscape design, green infrastructure concepts incorporate or extend “Low Impact Development” (LID) principles. Prince George’s County, Maryland, pioneered the use of LID principles to cope with stormwater and water quality impairment, substituting landscape design elements for conventional pipe-based structural methods to retain and filter runoff from development projects.
As EPA noted when introducing its 2008 Green Infrastructure Action Strategy, with a “Statement of Intent” and a “Statement of Support” attached: Green infrastructure “has been used differently in different contexts. [F]or the purposes of our efforts … we intend the term ‘green infrastructure’ to generally refer to systems and practices that use or mimic natural processes to infiltrate, evapotranspirate . . . or reuse stormwater or runoff on the site where it is generated.”
The impetus for green infrastructure projects under the CWA
Today’s explicit attention to green infrastructure at the municipal scale coincides with enforcement efforts to bring municipalities and their water and sewer authorities into compliance with the pollution control provisions of the federal CWA. The momentum, funding, and timing of green infrastructure projects are related to the tardy but ongoing implementation of the CWA’s National Pollutant Discharge Elimination System (NPDES) pollution control requirements for combined sewer overflows (CSOs) and municipal separate storm sewer system (MS4) discharges.
The CWA prohibits the “discharge of any pollutant” except in compliance with the provisions of the statute, including compliance with an NPDES permit authorizing the discharge. 33 U.S.C. §§ 1311(a),1342. While many cities and towns have separate piped systems for sanitary sewage and stormwater conveyance, some of the nation’s largest and oldest cities have aging combined sewer systems (CSSs) with insufficient capacity to hold the mixture of sewage and stormwater during times of high precipitation. The resulting CSO discharges to waterways cause exceedences of water quality standards and violate the terms of NPDES permits issued under the federal or delegated state permit programs.
Recent consent agreements in CWA enforcement proceedings illustrate the incorporation of green infrastructure requirements. In Philadelphia, the commissioner of the Water Department has taken a national leadership role in articulating the promise and practicalities of green infrastructure programs. Through a 2011 administrative consent order with the Pennsylvania Department of Environmental Protection, a 2012 administrative consent order with EPA, and a 2012 partnership agreement with EPA, Philadelphia is addressing CSOs in its “Green City, Clean Waters” plans for green infrastructure projects. In New York, a 2012 administrative consent order issued by the state Department of Environmental Protection requires a complex combination of green infrastructure projects and gray infrastructure upgrades to deal with CSO pollution and implement federal and state water pollution requirements.
In Kansas City, a 2010 consent decree recognized the city’s national leadership in promoting “green solutions” to sewer overflows and stormwater problems. In Chicago, the Metropolitan Water Reclamation District (MWRD) likewise recently entered into a consent agreement to settle CWA litigation brought by the federal and state governments. The 2014 Chicago consent decree requires construction of a massive system of tunnels and reservoirs to control CSO discharges (the Tunnel and Reservoir Project or TARP), and implementation of a green infrastructure program to prevent millions of gallons of water from flowing directly into storm sewers during storms.
The Natural Resources Defense Council, a proponent of green infrastructure and signatory to EPA’s 2008 green infrastructure “Statement of Support,” opposed the entry of the Chicago consent decree, in part on grounds that the green infrastructure component was inadequate. The district court rejected the challenge: “The green infrastructure projects are not mandated as part of the TARP plan and are not required by any law. The green infrastructure plan is icing on the TARP cake, a bonus.” U.S. v. Metro. Water Reclamation Dist. of Greater Chicago, No. 11 C 8859, 2014 WL 64655, at *5 (N.D. Ill. Jan. 6, 2014). This commentary highlights the role of green infrastructure projects in the regulatory regime. Green infrastructure projects reduce the wet weather pollution that reaches federally regulated discharge points. They are adopted in the shadow of CWA enforcement, leveraged by EPA’s authority to demand onerous controls at the end of the pipe. The resulting consensual arrangements, when successfully implemented, combine local innovation and initiative with the clout of the federal permit system.
The role of municipal authorities in implementing green infrastructure programs has also expanded in light of CWA requirements for MS4 permits. These permits “require controls to reduce the discharge of pollutants to the maximum extent practicable, including management practices, control techniques and system, design and engineering methods, and such other provisions as the Administrator or the State determines appropriate for the control of such pollutants.” 33 U.S.C. § 1342(p)(3)(B). MS4 regulation thus involves an iterative process for determining best management practices.
Recent citizens’ group litigation in Pittsburgh illustrates both the room for municipal discretion and innovation in the planning process and the potential importance of local regulatory systems in meeting federal and state permit conditions. A citizens’ suit against the Pittsburgh Water and Sewer Authority and the City of Pittsburgh alleged a failure to enforce city ordinances that included green infrastructure mandates and special planning requirements for publicly funded development projects. The U.S. District Court ultimately concluded that the NPDES permit conditions did not explicitly require compliance with these local provisions and did not give rise to CWA claims cognizable in federal court. Nonetheless, the rulings in the case implicitly recognized that such municipal requirements might be federally enforceable if explicitly incorporated in NPDES permit conditions. Citizens for Pennsylvania’s Future v. Pittsburgh Water and Sewer Authority, Civ. Action No. 12-943, 2013 WL 6838690 (W.D. Pa. Dec. 27, 2013) and 2014 WL 1356134 (W.D. Pa. Apr. 7, 2014).
Delays in further expanding CWA green infrastructure mandates
EPA has expanded its technical guidance, instructional videos, and grants and awards for green infrastructure projects. It has also encouraged integrated plans for stormwater and wastewater management, coordinating green infrastructure solutions to address multiple water quality issues simultaneously. In turn, municipalities have passed ordinances, established stormwater districts, and adopted fee mechanisms to finance stormwater management systems. Nevertheless, EPA has been under pressure from advocacy groups to establish more far-reaching federal requirements for both municipal and nonmunicipal stormwater discharges. In a 2010 settlement of litigation brought by the Chesapeake Bay Foundation, EPA agreed to propose rules by a 2011 deadline (later extended to 2013), and to finalize regulations the following year, for developed and redeveloped sites in communities with MS4s. The suit was dismissed in light of the agreement. Fowler v. EPA, No. 1:09-cv-00005, 2010 WL 8757719 (D.D.C. May 19, 2010). But the rulemaking remains stalled.
Citizens groups in three EPA regions also filed petitions asking EPA to flex its “residual designation” authority under section 402(p) of the CWA to regulate stormwater discharges from currently unregulated commercial, industrial, and institutional (CII) sites such as mall parking lots and big-box stores. EPA Regions 3 and 9 denied the petitions, citing lack of data and reliance on other programs. EPA Region 1, on the other hand, again deferred decision making, stating it would now evaluate water quality impairment on a localized basis in watersheds where EPA has already determined that stormwater is a significant contributor of pollutants causing water quality standards to be exceeded.
Green infrastructure requirements have become an integral aspect of water and sewer planning in urban areas where stormwater pollution caused by runoff from impervious surfaces and intermingling with sanitary sewage are serious problems. Settlements of CWA enforcement actions, coupled with federal and state funding for pilot projects, have done much to spur municipal green infrastructure initiatives. But further steps at the federal level to expand green infrastructure policies by regulation will undoubtedly face continuing challenges.