Amendments to the California Industrial General Storm Water Permit on the Horizon

Water Law  

January 9, 2018

The California State Water Resources Control Board will be considering amendments to Industrial General Storm Water Permit at a workshop today, January 9, 2018 and can be watched on a webcast available here –

On December 15th, the State Water Board staff proposed amendments to the Industrial General Storm Water Permit to incorporate proposed Total Maximum Daily Load (“TMDL”) implementation language, and to provide new potential compliance options.

The new amendments add new TMDL Numeric Action Levels (“TNALs”) and Numeric Effluent Limitations (“NELs”) not included in the previous permit that add more possibilities for permit violations and liability.

TNALs are pollutant concentration levels used to evaluate if Best Management Practices (“BMPs”) are effective and if additional measures are necessary to control pollutants to comply with applicable TMDLs.

All TNALs translated from a Waste Load Allocation are instantaneous maximums, and are set forth in the TMDL Compliance Table in new Attachment E.

Unlike NELs, TNALs are not effluent limits, and the exceedance of a TNAL is not a permit violation. However, as we know from the current permit, allegations of non-compliance will be made if discharges exceed the TNALs.

All TNALs are instantaneous maxima, not annual averages, and a TNAL exceedance occurs when two or more analytical results from samples taken for any parameter within a reporting year exceed the instantaneous maximum TNAL value in the TMDL Compliance Table in Attachment E.

NELs, set as both concentration and dry weight (μg/kg) limits, will constitute a violation of the permit if exceeded. It is unclear why NELs are being imposed when previous findings were that such limits were infeasible.

The amendments proposed also provide new on-site and off-site compliance options in additional to traditional compliance. However, the emphasis is on storage and infiltration (which does not allow ground water impacts), or diversion to sanitary sewer (which may be prohibited in some areas of the state).  

Although these are set forth as options, it may be that businesses have little choice since the number of lawsuits alleging non-compliance with the current permit have been more prevalent than expected. 

Other changes blur the lines of where compliance must be demonstrated for receiving water limitation compliance.

Written comments are due at noon on February 14, 2018.