Permits for Domestic Discharges to Surface Water


Permits to discharge treated domestic waste (sewage) to surface water are handled by Permits Unit 2, which is managed by Michelle DeLaria:

General Permits for Facilities Under 1 mgd

WQCD encourages applicants under 1 mgd to consider coverage under the two surface water domestic general permits because general permits pose a number of advantages for planning and timing:
  • General permit certifications can be issued far more quickly than individual permits, which may allow you to skip the PEL stage and use your permit as your Water Quality Planning Target.
  • Certifications under existing general permits may offer dischargers engaged in long-term planning more certainty than individual permits.
  • In many cases, general permit certifications can be modified after the general permit has been administratively extended (as long as the general permit itself does not need to be modified). Individual permits cannot be modified after the permit has been administratively extended.
  • General permit PELs can be completed more quickly than individual permit PELs.
  • General permit PEL and permit fees are lower.

Note that the two surface water general permits also provide for dilution in accordance with established tables in the permits. In addition, antidegradation limits will not be applied to permittees qualifying for coverage under the COG590000.

Qualifications for coverage under the COG590000 (100:1 Dilution General Permit)

In order for the facility to qualify for a General Permit COG590000, the facility must meet all the requirements above for the COG589000 permit, AND the receiving stream must provide 100:1 dilution.  The dilution ratio is the 30E3 (chronic low flow) of the receiving stream (just above the outfall) to the facility design flow. In addition, the facility cannot discharge to waters designated as threatened and endangered species habitat. If your facility does not meet these qualifications but you are under 1 mgd, you are probably qualified for coverage under the COG589000/COG591000 - see below.

The COG590000 general permit has replaced the COG588000 general permit as of April 1, 2021. New facilities and conversions from an individual permit that qualify should apply under the COG590000 general permit. The division plans to renew existing facilities that are currently permitted under the COG588000 general permit under the new COG590000 general permit in 2021.

2022 Renewal of COG589000 - Becoming COG591000

The Water Quality Control Division is beginning the process of renewing General Permit COG589000 in 2022. 

Upon renewal, the permit will be numbered COG591000. Current COG589000 permittees will be renewed under the new COG591000; small facilities under other general permits or that hold individual permits will also be able to move to the COG591000. 

Applications for a permit, WQPT or a PEL for a facility under 1 mgd with less than 100:1 dilution that are submitted after 1/30/2022 will be held for drafting until the COG591000 is effective, because the division plans to have the COG591000 renewal permit effective within 180 days.

Materials about the renewal process, including slides and a recording of the 1/26 stakeholder meeting, can be found in this folder.

If you have questions about the upcoming renewal process or would like to be added to the notification list, please contact Kelly Drengler at

Links to Permit Documents and Applications

  • PREVIOUS Domestic wastewater treatment plant with chronic low-flow design ratio 100:1 (COG588000). Applications are no longer accepted for coverage under this permit.
  • New or Renew individual permit for domestic system.
    • Application.
    • Note you must file your renewal application at least 180 days before the permit’s expiration date if you would like your permit to be administratively extended.
    • Note that individual domestic permits are renewed following the division’s basin schedule, which can be found at
  • Permitting forms webpage where you can find forms for modification requests, notices of transfer, withdrawal requests, application supplement forms, and requests for chemical evaluation

Facility Planning and Site Approval

Sewage system compliance assistance and guidance