The Draft Industrial Storm Water General Permit includes new "exceedance response action" (ERA) requirements for facilities whose storm water sampling results exceed triggers based on Numeric Action Levels (NALs), largely based on the USEPA's Multisector General Permit "benchmark monitoring" references list. The stated purpose of the ERA process is to help ensure that Dischargers are using adequate best management practices (BMPs), by requiring that those subject to ERAs evaluate their BMPs to ensure they meet the technology-based narrative limits. Further, additional best management practices must be adopted if necessary to avoid causing or contributing to instream (receiving water) conditions exceeding water quality standards.

Previous formal public drafts issued in 2005, 2011 and 2012 generated significant controversy. They focused first, on a proposal to make the action levels true numeric effluent limits, creating permit violations if exceeded.  Numeric effluent limits are difficult or impossible to set properly for variable wet weather runoff and site conditions. Controversy in the most recent drafts has focused on whether the NALs create "virtual" numeric effluent limits, by requiring ever increasing corrective action efforts until the NALs are not exceeded.  The 2013 draft specifies that the NALs are not to be considered effluent limits, and exceedances are therefore not violations of the permit. However, under the current draft, exceedances can trigger a rigorous evaluation and site improvement process documented in a series of technical reports, unless a site can demonstrate, and certify annually, that the exceedance was caused by separate non-industrial sources, run on, or background conditions.

Non-government organizations (NGOs), who have filed hundreds of citizen suits against industrial facility operators state-wide revised , have asked that the General Permit make explicit that the procedures in the permit provide no "safe harbor." Operators and local government stormwater system operators continue to press for clear and feasible standards that will assure permit compliance. A mandate to electronically file applications, maps and full copies of the site’s stormwater pollution prevention plan (SWPPP) continue to raise some concerns, as does the January effective date that splits a wet season.  In addition, there are a number of areas needing clarification, including standards for minimum BMPs.

Other changes in the permit include more extensive discharge monitoring (two samples before January 1 and two after January 1 each year), new approaches to pH monitoring, and monthly inspections (in this draft these are made less onerous than the last proposal’s pre-storm inspection requirements).  While earlier drafts proposed to eliminate the option of monitoring groups with streamlined requirements, the current draft restores the option, while increasing the stringency of requirements for group members.