Wyoming SWPPP inspection requirements

The short version
Rain trigger
0.5″ storm event
Post-rain deadline
Within 24 hours
Routine inspections
Every 7 or 14 days
Permit
Large Construction General Permit (WYR10, administratively continued)
Agency
Wyoming Department of Environmental Quality (WY DEQ)

Verify against your permit. These values reflect the most common reading of Wyoming's program; permits change and projects vary. The official permit text from WY DEQ controls.

How Wyoming handles construction stormwater

Construction sites in Wyoming disturbing one acre or more need coverage under the Large Construction General Permit (WYR10, administratively continued), administered by Wyoming Department of Environmental Quality. Inspect every 14 days plus within 24 hours after a 0.5″ storm, or every 7 days with no storm trigger (every 30 days during inactive periods). The 2020 Large CGP ran through August 1, 2025 and is administratively continued; a combined WYR100000 renewal covering large and small construction closed public comment June 15, 2026 and is pending issuance — re-verify when it lands.

Inspector qualifications

A qualified person designated by the operator. Check the current state permit for certification requirements.

Official sources

Common questions

What triggers a SWPPP inspection in Wyoming?

Under the Large Construction General Permit (WYR10, administratively continued), a storm event of 0.5 inches or more triggers a post-storm inspection, within 24 hours (non-work days typically extend to the next work day; check your permit). Routine inspections: every 7 or 14 days.

Who can perform SWPPP inspections in Wyoming?

A qualified person designated by the operator. Check the current state permit for certification requirements.

Who administers the construction stormwater program in Wyoming?

Wyoming Department of Environmental Quality (WY DEQ) administers the NPDES construction stormwater program in Wyoming under the Large Construction General Permit (WYR10, administratively continued).

What are the penalties for SWPPP violations in Wyoming?

Federal Clean Water Act civil penalties can reach $68,445 per day per violation, and WY DEQ can issue administrative orders and state penalties on top. Missing rain-triggered inspections is among the most commonly cited violations in stormwater audits.

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