On April 24, the Washington Department of Ecology hosted a virtual informational presentation on the upcoming reissuance of the 2026 Construction Stormwater General Permit (CSGP). In this post, we will go over everything discussed at this presentation.

Click here to read the draft permit

Click here to submit a public comment to ecology

Key Presentation Takeaways:

1. Timeline:

• May 9, 2025– Formal comment period ends
• July 3,2025– Deadline to reapply for coverage-“Duty to Reapply”
• November 19, 2025- Ecology plans to release final permit and response to comment
• December 31, 2025– Current permit expires
• January 1, 2026– New permit goes into effect

2. The basics and framework of the permit will remain unchanged

As with previous permits, the proposed 2026 permit will retain the same framework for:

• Minimum Coverage Requirements– Sites over one acre in size that discharge to surface waters of the state or sites determined to be significant contributors of pollutants will need permit coverage.
• Use of BMPs– Permittees will continue to use Best Management Practices (BMPs) to proactively protect from stormwater pollution on their site.
• Stormwater Pollution Prevention Plan (SWPPP)– Permittees will continue to maintain a SWPPP on site detailing how stormwater will be protected on site and how their stormwater program will be implemented.
• Inspections/ Sampling- Frequency of inspections and sampling will remain largely unchanged for sites over one acre.
• Reporting and Paperwork- The reporting requirements such as DMRs and ERTS along with termination of coverage will remain largely unchanged.

3. New emphasis on construction support activity

• There is a new definition of construction support activity in the draft permit-
  • Construction Support Activity- means on or off-site acreage that will be disturbed as a direct
    result of the construction project and will discharge stormwater. Construction-support
    activities may include, but are not limited to: equipment staging, borrow pit, material
    storage areas, dump areas, haul roads, construction roads, side-cast areas, on-site portable
    rock crusher, staging yards, parking areas, off-site construction support activities and all
    other soil disturbing.
  • These areas of construction support activity needs to be included in the calculation of area of soil disturbance

    

4. New application requirements

• Contaminated Sites- The draft permit includes clarification as to what constitutes a contaminated site and what documentation applicants need to provide. Ecology hopes that this will reduce the extended review time that typically accompanies projects on contaminated sites.
• Partial Transfers/ Acreage Updates- The draft permit requires partial transfers or sites updating their coverage acreage to submit updated site maps clarifying the site boundaries with the intent to  help with site inspections.

5. San Francisco v EPA decision

• The San Francisco v EPA decision found that NPDES permits need to provide specific actionable limitations on dischargers not broad mandates tied to the overall quality of receiving waters. As a result of this decision, Section S3A from the previous permit has been removed.
  • The removed section read “Discharges must not cause or contribute to a violation of surface water quality standards (Chapter 173-201A WAC), groundwater quality standards (Chapter 173-200 WAC), sediment management standards (Chapter 173-204 WAC), and human health-based criteria in the Federal water quality criteria applicable to Washington. (40 CFR Part 131.45) Discharges that are not in compliance with these standards are prohibited.”

6. Changes for sites under 1 acre

• Coverage requirements remain unchanged- Sites over one acre that discharge to surface waters of the state typically require coverage.
• Some conditions may require coverage for smaller sites- Municipal requirements, company policy, ecology determination.
• Historically these sites had fewer requirements under the CSGP, however the draft permit would require these sites to have the same requirements as all sites under 5 acres.
• Changes include:
  • All inspections conducted by a CESCL.
  • Weekly turbidity and pH sampling.

7. Discharges to impaired waterbodies

• Under the draft permit, sites discharging to 303(d) listed waters for low dissolved oxygen will have a numeric effluent limit for turbidity.
• The draft permit also states that sites discharging dewatering water to 303(d) listed waterbodies will need to sample daily if discharging.

8. Updates to Stormwater Management Manuals leads to changes SWPPP BMPs

• Permittees should review the following BMPs so their SWPPP matches requirements in Stormwater Management Manuals:
  • Construction Entrances- no use of recycled concrete
  • Protect Slopes
  • Stabilize Channels/ Outlets
  • Protect LID/ Infiltration BMPs

9. New Definitions in Permit

• Construction Support Activity- means on or off-site acreage that will be disturbed as a direct
  result of the construction project and will discharge stormwater. Construction-support
  activities may include, but are not limited to: equipment staging, borrow pit, material
  storage areas, dump areas, haul roads, construction roads, side-cast areas, on-site portable
  rock crusher, staging yards, parking areas, off-site construction support activities and all
  other soil disturbing.
•  Operational Hours– means when work is happening on site related to the project and project support activities, whether the activities are scheduled or unscheduled

Summary of Questions Asked:

*Note: Questions and answers posted below are paraphrased based off of notes taken during the meeting and are posted here for clarity purposes only,  as always you should reach out directly to Ecology for compliance questions regarding the CSGP.

Q: Can you clarify when a site under 1 acre might need coverage

A: Typically not needed, but in cases such as a contaminated site it may be. In some cases it may be required by municipal code or a specific company policy.

Q: Operational Hours definition mentions “whether the activities are scheduled or unscheduled” can you give an example of activity that is not scheduled?

A: Examples may include a site emergency or workers on site during the weekend due to a delay or similar. Good rule of thumb is any activity directly related to the project is operational hours, but this wouldn’t include activity like a security guard patrolling.

Q:  Will folks need to keep a calibration log with their calibrated pH meter?

A: The permit doesn’t require a log specifically, but ecology was unsure if it is in EPA method, and if it is in that method,  then you should have a calibration log.

Q:  Can you better define what “Outside normal working hours” are*?

A: Refer to definition of operational hours, when work is happening on site related to the project and support activities

* Note a user indicated that the permit uses “working hours” but defines “operational hours”- Ecology indicated that this may be a good opportunity for public comment.

Q: Can you clarify why S3A was removed from the permit?

A: This was a direct result of the San Francisco v EPA decision.

Q: Can you clarify S1B1A (pg.4) regarding who needs permit coverage. Is the 1 acre soil disturbance determination from the sum of all construction and support activity, or each of these activities individually?

A: The total sum of these activities including construction support activity, refer to S1B1b for clarity on what may constitute support activity

Q: Is there any discussion about allowing electronic NOIs?

A: It is state law that they cannot utilize electronic signatures, and while this has been discussed, Ecology will continue to require wet ink signatures.

Q: Do construction support activity areas literally need to disturb the soil to be counted in the acreage?

A: There is nuance here, but a good rule of thumb is support activity like equipment storage that occurs on impervious surface such as a paved parking lot wouldn’t count towards that disturbed area calculation, but this activity taking place on a pervious surface such as the bare ground or gravel would.

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For questions regarding your  Construction Stormwater General Permit, reach out to Brandon Boyd at [email protected]