WSR 03-15-081


[ Filed July 16, 2003, 4:05 p.m. ]

Ecology to Rewrite and Reissue Water Treatment Plant General Permit

The Washington State Department of Ecology (ecology) is beginning a process to update and reissue the water treatment plant general permit (WTP GP). The WTP GP is issued in compliance with the national pollutant discharge elimination system (NPDES), the Clean Water Act, and state law governing wastewater discharges. This permit authorizes the discharge of filter backwash from water treatment plants subject to the terms and conditions of the permit. This permit applies only to discharges to surface waters. A final draft permit is targeted for December 2003.

The current permit was issued on December 3, 1997, and expired on February 1, 2003. The permit has been administratively extended for those facilities with permit coverage. The rewrite of the permit will consider what was learned from data collection and site inspections during the first five years of the permit. The rewrite will consider the potential of discharges from these facilities to violate water quality standards and whether there are any changes in the industry standard for wastewater treatment prior to discharge.

The WTP GP is a statewide permit providing permit coverage for thirty water treatment plants. Water treatment plants under this permit treat water through filtration processes producing a finish water for drinking or for industrial activities. The filtration process removes dirt, organics, microorganisms, and other impurities, trapping this material in the filter. The filters must periodically be backflushed to remove the trapped material restoring filtration capacity. The wastewater from this industry is composed of the backflush water and periodic cleaning of any pretreatment chambers or devices. Potential pollutants include the dirt, organics, microorganisms and other impurities removed during filtration as well as additives. Additives may include chlorine, chemicals to adjust pH, and chemicals that enhance the removal of impurities in the water.

Parties interested in receiving information on the reissue process and participating in the rewrite should contact ecology through Keith Johnson, e-mail, phone (360) 407-6442, Department of Ecology, P.O. Box 47600, Olympia, WA 98504; or Carey Cholski, e-mail, phone (360) 407-6279, Department of Ecology, P.O. Box 47775, Olympia, WA 98504.

Additional information on the current WTP GP, the fact sheet for the 1997 permit and ongoing releases of information on the reissue process and issues can be found on ecology's web page at

Ecology is an equal opportunity agency. If you have special accommodation needs or require information in an alternative format, please contact Keith Johnson at (360) 407-6442 or TDD (only) - (360) 407-6006.

Legislature Code Reviser 


Washington State Code Reviser's Office