Washington
The stormwater permit for construction in Washington
Washington runs its own NPDES programme, so a state issued construction general permit governs. Below is what our engine can say about it, and where we have not read that permit, what it will not say.
Governing permit
Construction Stormwater General Permit (CSWGP), issued November 19, 2025, effective January 1, 2026
- Issued by
- Washington State Department of Ecology (Ecology)
- Version determined against
- as published by the state agency
- Effective
- 2026-01-01
- Expires
- 2030-12-31
Who may prepare the plan
No preparer credential foundNo preparer credential was found for Washington. On what we have verified, a generated plan can be adopted by the operator without a credentialed signature. Local ordinances can still be stricter than state law.
CSWGP Section 9 contains no professional-engineer or licensure requirement. CESCL is inspection-scoped under S4.B.
No permit section cited. Confirm this with your permitting authority.
Does a site in Washington need coverage
Worked for a one acre site as a reference point. Change the acreage in the tool below and the answer, and its reasoning, change with it.
Coverage
Permit coverage required
The project disturbs 1 acres, at or above the 1 acre threshold, so it needs permit coverage.
Determined against dataset version 2026-07-19.
Read these before you act on the answer
- Requirements below are what we have read and cited directly from Construction Stormwater General Permit (CSWGP), issued November 19, 2025, effective January 1, 2026, not the federal CGP. A category we have not yet transcribed from this permit is omitted here rather than assumed to match EPA's rule.
- No explicit permit/order number (e.g., a 'WAR-xxxxxx' style code) appears anywhere on the permit cover page, errata, or table of contents of either the current 2026 permit or the prior 2015/2020 permit checked for comparison — Washington identifies this general permit by name plus issuance/effective/expiration dates only, not a discrete number. No numeric buffer setback distance (feet) is specified in the permit itself; it requires 'natural buffers around surface waters' (S9.D.4.e) but defines 'Buffer' as an area designated by the local jurisdiction (Appendix A), so no state-level distanceFeet value could be verified. No fixed-hour deadline for producing/submitting the routine inspection report itself was found (only content requirements). NOT (Notice of Termination) has no fixed day-count filing deadline — it is filed once a site becomes eligible, so it was not forced into the federal 'deadline.not.submission' shape.
- No preparer credential was found for Washington. On what we have verified, a generated plan can be adopted by the operator without a credentialed signature. Local ordinances can still be stricter than state law.
- Basinwise does not perform the physical site inspections the permit requires. Those must be carried out on site by a qualified person.
How this answer was reached, step by step
- 1
Coverage threshold
The project disturbs 1 acres, at or above the 1 acre threshold, so it needs permit coverage.
- 2
Permitting authority
Washington. The state runs its own programme, issued as an unnumbered or rule-based general permit rather than under a discrete permit number.
- 3
Preparer credential
No preparer credential was found for Washington. On what we have verified, a generated plan can be adopted by the operator without a credentialed signature. Local ordinances can still be stricter than state law.
What to do next
- 1. Confirm the governing permit. Read Construction Stormwater General Permit (CSWGP), issued November 19, 2025, effective January 1, 2026 directly. It is linked above, and it is the document an inspector will hold you to. Washington State Department of Ecology (Ecology)
- 2. Settle the preparer question before you draft. Getting this wrong costs a redraft at best. The detail is on the credential page for this state. Preparer credential in Washington
- 3. Screen the site. Run the real acreage and receiving water facts through the tool below. You get the inspection frequency, the stabilisation deadlines and the filing path with the permit section behind each.
- 4. Read the requirements in full. SWPPP requirements in Washington
Screen a Washington site now
Runs in your browser. Nothing about the site is transmitted.
What people ask about the Washington construction stormwater permit
Do I need a stormwater permit for a construction site in Washington?
Permit coverage is triggered at one acre of land disturbance, and below one acre if the project is part of a larger common plan of development or sale that will ultimately disturb an acre or more. The project disturbs 1 acres, at or above the 1 acre threshold, so it needs permit coverage.
Who issues the construction stormwater permit in Washington?
Washington State Department of Ecology (Ecology) issues Construction Stormwater General Permit (CSWGP), issued November 19, 2025, effective January 1, 2026.
Does Washington require a qualified preparer for the plan?
No preparer credential was found for Washington. On what we have verified, a generated plan can be adopted by the operator without a credentialed signature. Local ordinances can still be stricter than state law.
Keep the record Washington will ask you for
The screening is free. Holding the written plan and the retained inspection log is what the permit actually demands.