WAState-AdministeredSWPPP Requirements in Washington
Washington State administers its own NPDES program through the Department of Ecology. The Construction Stormwater General Permit imposes numeric turbidity standards (25 NTU benchmark, 250 NTU limit) that are among the strictest in the US. A CESCL must be on-site during earth disturbance, and monthly eDMRs are required. The wet season (October–April) demands heightened BMP implementation.
Washington SWPPP Key Facts
- ✓Numeric turbidity benchmark: 25 NTU; limit: 250 NTU — among the strictest numeric standards in the US
- ✓CESCL (Certified Erosion and Sediment Control Lead) required on-site during active construction
- ✓Monthly electronic Discharge Monitoring Reports (eDMRs) required through WA Ecology portal
- ✓Wet season (October–April) triggers enhanced BMP requirements — western WA averages 150+ rainy days per year
- ✓$500 NOI application fee plus $500+ annual fee based on acreage
- ✓Puget Sound watershed receives elevated regulatory attention — enhanced turbidity protections near marine waters
- ✓Eastern WA (east of the Cascades) is semi-arid with fundamentally different BMP design needs than western WA
- ✓WA Ecology has authority to require individual permits for sites with repeated turbidity exceedances
Administering Agency
- Agency
- Washington State Department of Ecology (WA Ecology)
- Phone
- 360-407-6000
- stormwater@ecy.wa.gov
Permit Details
- Permit Name
- Construction Stormwater General Permit
- Effective Date
- 2026-01-01
- Expiration Date
- 2030-12-31
- Permit Document
- View Current Permit
SWPPP Thresholds & Triggers
- Acreage Threshold
- 1 acre or more; less than 1 acre if part of a larger common plan of development
Numeric turbidity benchmark of 25 NTU and limit of 250 NTU applies. Projects near 303(d)-listed water bodies face enhanced requirements.
Inspection Requirements
- Inspection Frequency
- Every 7 days and within 24 hours of a 0.5-inch or greater storm event
- Rain Event Threshold
- 0.5 inches within 24 hours
- Certified Inspector
- Required by state
- Accepted Certifications
- CESCL (Certified Erosion and Sediment Control Lead) — required on-site during construction, CPESC, PE licensed in WA
A CESCL must be present on-site or on-call at all times during active construction. Electronic Discharge Monitoring Reports (eDMRs) required monthly.
Penalties & Enforcement
- Max Civil Penalty (Per Day)
- $10,000 per day per violation
- Criminal Penalties
- Up to $10,000/day for criminal violations
WA Ecology uses a tiered enforcement approach including NOVs, penalty orders, and permit suspension for turbidity exceedances.
Permit Fees
- NOI Filing Fee
- $500 application fee
- Annual Fee
- $500+ depending on acreage
- Other Fees
- Electronic reporting via WA Ecology's Water Quality Portal
How Washington Differs from Federal Requirements
- ⚠WA has its own NPDES program; EPA CGP does not apply
- ⚠Numeric turbidity limits (25/250 NTU) are stricter than federal CGP
- ⚠CESCL on-site requirement is WA-specific
- ⚠Monthly eDMR reporting exceeds federal CGP requirements
- ⚠$500 permit fee not required under federal CGP
SWPPP Tips for Washington
- ➤Install and inspect turbidity curtains before the October wet season begins — western WA construction must be prepared for continuous rain from October through April
- ➤CESCL certification is site-specific — ensure the on-site CESCL is named on your NOI and their certification is current (recertification required every 3 years)
- ➤Turbidity sampling is required before any discharge — document results in your monthly eDMR and keep backup records on-site
- ➤Size sediment ponds for western WA's sustained rainfall, not just single-event storms — prolonged low-intensity rain generates more total runoff than short intense events
- ➤For Puget Sound watershed sites, use enhanced turbidity controls (chitosan, PAM, or active treatment) to meet the 25 NTU benchmark during wet-season grading
- ➤Eastern WA projects should focus on wind erosion and concentrated flow controls — the semi-arid climate east of the Cascades produces episodic high-intensity runoff
- ➤Keep a turbidity meter calibrated and on-site at all times — WA Ecology inspectors will ask to see your monitoring equipment and sampling records
Washington SWPPP FAQs
What does CESCL certification require?+
CESCL candidates must complete an approved 1-day training course covering erosion control, inspection, and stormwater regulations, then pass an exam. Recertification is required every 3 years. The CESCL must be on-site or on-call during all phases of earth disturbance. Approved training providers are listed on WA Ecology's website.
When must eDMRs be submitted?+
Monthly eDMRs are due by the 15th of the following month and must report turbidity sampling results, inspection findings, and any discharges. Submission is through WA Ecology's Water Quality Portal. Failure to submit eDMRs on time is a permit violation even if no discharge occurred.
What happens if turbidity exceeds 250 NTU?+
Discharge must cease immediately, corrective action must be implemented, and an exceedance report must be filed with WA Ecology within 24 hours. Repeated exceedances can trigger WA Ecology to require an individual permit with more stringent conditions. Document all corrective actions taken with timestamped photos.
How does the 25 NTU benchmark differ from the 250 NTU limit?+
The 25 NTU benchmark is a trigger for corrective action — if your discharge exceeds 25 NTU, you must review and adjust BMPs but may continue discharging. The 250 NTU limit is a hard cap — exceeding it requires immediate discharge cessation and reporting. Both are measured at the point of discharge from the site.
Do I need a permit for construction in eastern Washington?+
Yes — the same Construction Stormwater General Permit applies statewide. However, eastern WA's semi-arid climate (8-15 inches annual rainfall east of the Cascades) means qualifying rain events are less frequent but often more intense. BMP design should reflect concentrated flow management and wind erosion control rather than the sustained-rainfall approach used in western WA.
What are active treatment systems and when are they required?+
Active treatment systems (such as chitosan-enhanced sand filtration or electrocoagulation) are engineered treatment methods used when passive BMPs cannot meet the 25 NTU benchmark. While not explicitly required by the permit, WA Ecology strongly recommends active treatment for sites with persistent turbidity issues, particularly those discharging to salmon-bearing streams in the Puget Sound watershed.
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