Proposed revisions to TCEQ’s water quality standards ("WQS") are currently out for public comment as part of the triennial review process required by the Clean Water Act (“CWA”) and the delegated TPDES program in Texas.  Changes in WQS that TCEQ finalizes after the public comment period could affect specific TPDES permits on a case-by-case basis if the adopted WQS alter requirements for the receiving waters for a particular industrial discharge.  Changes driven by the new WQS could include best management practices and/or modified treatment requirements, depending on whether a standard has been lowered or increased.   These types of changes are typically implemented as part of the TPDES permit renewal process for point source dischargers.

WQS changes of a more general nature that will likely impact industry include TCEQ’s proposals: (1) specifying that industrial cooling water areas are exempt from certain numeric temperature criteria; (2) modifying certain mixing zone criteria and clarification that mixing zones may vary for different types of numeric criteria; and (3) significantly lowering mercury criteria in both freshwater and saltwater in response to EPA’s 2011 disapproval of TCEQ’s current mercury water column criteria.

Public comment on the proposed WQS is open until October 24, 2013, with a possible public hearing (if requested) scheduled for October 17, 2013. TCEQ’s anticipated adoption date for the finalized WQS modifications is early February 2014.