Thank you for the opportunity to comment on the draft VPDES Permit for Discharges of Storm Water Associated with Industrial Activity.

Arlington County's comments come from our perspective as a regulated MS4 with a Chesapeake Bay TMDL wasteload allocation (WLA).  Arlington's Phase I permit, as well as the new Small MS4 permits, contain a loading table to determine the specific Bay TMDL load reductions required during this permit cycle.  The input into this loading table is the permittee's MS4 service area.   A key element of the MS4 service area computation is excluding lands covered under separate VPDES stormwater permits. 

This is a fundamental aspect of how the Clean Water Act (CWA) regulates point sources governed by a TMDL:  each point source is responsible for its own discharges and is assigned a WLA for which it is responsible.    VPDES-permitted industrial stormwater facilities are not an exception, yet the draft permit does not include a Bay TMDL WLA.  This is inconsistent with the CWA, especially when considering that the Act applies a less stringent regulatory standard to MS4s than to industrial stormwater dischargers.   In short, if MS4s have a Bay TMDL WLA, than industrial stormwater discharges must also be assigned a Bay TMDL WLA.

EPA's Bay TMDL reinforces this basic legal and regulatory principle by highlighting in numerous places the category of industrial stormwater discharges as distinct from MS4 discharges. The document also specifically states that the TMDL includes a separate category of loads for industrial stormwater facilities:

The contribution from industrial stormwater discharges subject to NPDES permits has been estimated on the basis of data submitted by jurisdictions in their Phase I WIPs, including the number of industrial stormwater permits per county and the number of urban acres regulated by industrial stormwater permits. For the Bay TMDL, the permitted industrial stormwater load is subtracted from the MS4 load when applicable. 

"When applicable" clearly applies in Virginia, with MS4s being assigned separate WLAs and having no regulatory authority over permitted industrial stormwater discharges.  Part 1.A.1.b of Arlington's MS4 permit states that VPDES permitted industrial stormwater discharges are automatically authorized to our MS4.  This highlights two critical points: 1) that MS4s have no regulatory authority over these discharges, and 2) that DEQ must exercise its clear authority over permitted industrial stormwater dischargers to ensure compliance with the Bay TMDL and other TMDLs.

The draft permit's definitions section is also very clear that all point source dischargers are assigned a WLA:

"Total maximum daily load" or "TMDL" means a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards, and an allocation of that amount to the pollutant's sources. A TMDL includes wasteload allocations (WLAs) for point source discharges, load allocations (LAs) for nonpoint sources and/or natural background, and must include a margin of safety (MOS) and account for seasonal variations.

If industrial stormwater facilities are not assigned a WLA, this load will go unaccounted for and will slow down the progress towards Bay restoration that we are all working hard to achieve.

Finally, the draft permit regulation (9VAC25-151-60.C.5) requires that the permittee identify whether the facilities discharges or will discharge to an MS4.  The MS4 must be involved in reviewing the permit if their location is within the corporate boundary.  For example, several currently permitted industrial stormwater dischargers in Arlington County discharge into VDOT’s MS4 and then into Arlington County's MS4.  Without the MS4s being included in the permit review process, it is unlikely that both would be identified on the permit.