Clearing the Water: 2016 Post Construction Stormwater Legislation
By:  Bill Penny

The commissioner of the Department of Environment and Conservation (TDEC) cannot impose post construction stormwater requirements more stringent than federal law in NPDES permits issued to local government municipal separate storm sewer systems (MS4s). This new requirement is the result of legislation advocated by the Home Builders Association of Tennessee (HBAT) and other building trade groups. The legislation passed the 2016 Tennessee General Assembly overwhelmingly as Senate Bill 1830/House Bill 1892 and is now Public Chapter 1007, Acts of 2016. MS4s are also required to have construction site stormwater and illicit discharge programs, and Public Chapter 1007 did not address those areas in any manner.

Federal law requires MS4s to seek authorization to discharge pollutants from their MS4 through an NPDES permit that provides, among other things, permanent post construction stormwater requirements for new development and redevelopment projects.  Section 402(p) of the Clean Water Act (CWA) contains Federal stormwater requirements for MS4s. The CWA allows local governments flexibility in implementation of the permits.

Federal rules require the MS4 to develop, implement and enforce stormwater management program designed to reduce the discharge of pollutants to the maximum extent practicable (MEP) to protect water quality and comply with water quality requirements of the CWA.  Larger MS4s, currently the four major metropolitan areas in Tennessee, are covered by individual NPDES permits from TDEC.  Small MS4s obtain coverage under TDEC's general MS4 stormwater permit.  As noted Chapter 1007 prohibits the state from imposing post construction stormwater requirements more stringent than federal law.  If a local MS4 wants to impose requirements as part of its MS4 NPDES permit over and above federal requirements, they may do so, but if they do, they must obtain authorization from the local governing authority.  The Act requires transparency for MS4s that choose to adopt more stringent federal requirements by requiring 30 days' notice of the proposed more stringent requirements.

After several years of severe recession in the home building industry, home building finally experienced revitalization, and the industry realized that Tennessee's 2010 small MS4 permit (the "2010 Permit") mandated permanent stormwater controls uniformly for all small MS4s throughout Tennessee regardless of topography, geology, or hydrogeology. This "one size fits all" approach was not only difficult to meet for projects in some areas, but also was not required by federal law.  Instead federal law gave the MS4 the authority and discretion to select the controls necessary to reduce the discharge of pollutants for post construction stormwater to the maximum extent practicable (MEP).  Chapter 1007 reiterates that post construction stormwater permits must allow the MS4 discretion in selecting measures to meet discharge requirements. Physical land features, for example, in Fayette County are substantially different than in Knox County.  The 2010 Permit mandated all MS4s to retain or infiltrate the first inch of a rainfall event. Soils in some areas of the state made such a requirement impracticable but federal requirements allowed the MS4 to employ other means to reduce the pollutants to the MEP. The added cost with no appreciable benefit made some development impracticable in some areas and a barrier to home ownership. As a result, some homebuilders began to invest in development in bordering states that did not have those requirements.
At the time the legislation passed most small MS4s had not yet imposed the post construction stormwater requirements of the 2010 Permit.  The 2010 Permit provided a phased in implementation approach to adopt ordinances or requirements with which to comply. TDEC initially extended the time to comply by one year and subsequently extended that to coincide with the time frame in the renewed MS4 permit expected to be issued this year.  As a result for most small MS4s the permanent stormwater measures are not yet in effect.  The legislation did not change compliance dates; such extensions were solely at TDEC's initiative.
 
The CWA's NPDES permitting authority is specifically limited to regulating the discharge of pollutants from point sources into jurisdictional waters, based upon the capabilities of the practices or technologies available to control such discharges.  33 U.S.C. §§ 1311(b)(2), 1314(b), 1316(b)(1)(B).  Stormwater flow, velocity, or quantity are not “pollutants” and cannot be separately regulated under the CWA and cannot be regulated as “proxies” or “surrogates” to effect levels of pollutants already present within a waterbody.  Virginia Department of Transportation v. U.S. Environmental Protection Agency, 2013 U.S. Dist. LEXIS 981 (E.D.Va. Jan. 3, 2013).  The EPA had proposed numeric stormwater requirements in just prior to the issuance of the 2010 Permit, but abandoned that regulatory approach in 2013 because of the high cost of implementation. The 2010 Permit contained some of those features and was more stringent than federal law.
Federal rules provide guidance to all MS4s in adopting controls to reduce pollutants to the maximum extent practicable.  40 CFR 122.34 states that narrative effluent limitations requiring implementation of best management practices (BMPs) are generally the most appropriate form of effluent limitations to reduce pollutants to the maximum extent practicable and to protect water quality.  EPA also recommends that BMPs chosen be appropriate for the local community.  Such BMPs include both nonstructural and structural BMPs.  However, permanent measures not directly related to the reduction of pollutants to the maximum extent practical are not required by federal law.  For example, many communities have combined flood control and stormwater requirements that may serve important local interests, but are not necessary to remove pollutants to the maximum extent practical as part of a post construction stormwater requirement.  MS4s are free to implement more stringent requirements such flood control as part of their permitting process as long as they identify those measures and have the local governing authority adopt an ordinance specifying the additional requirements.  Public Chapter 1007 does not restrict land use practices adopted independently of and not as a requirement for compliance with the NPDES MS4 permit.

Public Chapter 1007 does not prohibit an MS4 from using retention or infiltration requirements where it can do so to the maximum extent practicable for purposes of pollution reduction.  However, the extent to which an MS4 can do so will be determined by the MS4 and not a statewide determination of what constitutes MEP.  All required measures must be based on the limitation of maximum extent practicable which indicates intent that the measures be technological feasible and also economically feasible. For example, it may be conceivably possible to construct a flood wall around a development or to retain six inches of stormwater, but it would not be practicable to do so, as it would substantially alter the development to the extent that the development itself would not be practicable. 

Public Chapter 1007 has a phase in period that should allow the MS4 time to obtain approval of more stringent practices. Public Chapter 1007 allows the MS4 to continue under its existing stormwater ordinance, more stringent or not, until it obtains permit coverage under a new NPDES permit-- either the general MS4 permit or an individual permit.  So, MS4s can continue under existing ordinances until that time.  For the small MS4s the draft 2016 permit allows the 90 days to adopt the 2016 permit after it is effective.  The TDEC 2016 MS4 permit cannot be any more stringent than federal law so MS4s that follow that permit can easily determine whether their permits comply with the legislation.  In addition, the federal guidance identifies numerous BMPs that are effective in reducing pollutants to the maximum extent practicable.  Many MS4s have existing ordinances that provide broad authority to the administrative agency to establish rules governing stormwater rather than spell out requirements in the ordnances.  MS4s will need to evaluate their regulations to assure that their regulations are not more stringent than federal law when obtaining new permit coverage, and if they are request an ordinance change.

After passage, Governor Haslam threatened to veto the legislation, but he let the bill become law without his signature with a letter to Lt. Governor Ramsey that cited his concerns over limitations the bill placed on the State's ability to protect water resources.   However, Governor Haslam also told proponents of the legislation that he did not want the permits to be more stringent than federal law either; so as a practical matter the legislation does not change the administration's actual implementation of post construction stormwater requirements.  In his letter Governor Haslam also expressed concerns about what he believed was ambiguous and confusing language in the bill that would lead to costly litigation, though he did not identify the language of concern in his letter.   Nearly all MS4s will be following the TDEC MS4 permit so there should be little room for ambiguity.  MS4s that choose to adopt more robust measures will be able to avoid potential litigation by simply adopting an ordinance for any measure it believes is more stringent.
Public Chapter 1007 mandates that the Department have post construction stormwater requirements that are not more stringent than federal law.  The same is required of local MS4s, but clarifies that MS4s may have more stringent requirements as long as the local governing authority expressly authorizes it.  The legislation protects water quality by allowing a benchmark for regulation and authorizing local governments to develop permanent stormwater measures for new construction or redevelopment in a manner that best suits that community's ability to protect state water quality.