Maryland SWPPP inspection requirements
- Rain trigger
- 0.25″ storm event
- Post-rain deadline
- Within 24 hours (weekends count)
- Routine inspections
- Weekly + storm-triggered, or every 4 business days with no storm trigger (Tier II watersheds: twice per week)
- Permit
- General Permit 20-CP for Construction Activity
- Agency
- Maryland Department of the Environment (MDE)
How Maryland handles construction stormwater
Construction sites in Maryland disturbing one acre or more need coverage under the General Permit 20-CP for Construction Activity, administered by Maryland Department of the Environment. 20-CP is effective April 1, 2023 – March 31, 2028. Option (a): weekly plus within 24 hours after a 0.25″ storm (same day or next day — calendar-based); multi-day storms get an inspection after the first 0.25″ day AND after the storm ends. Option (b): every 4 business days with no storm trigger. Rain gauge or representative weather station required.
Inspector qualifications
Inspectors must hold a valid MDE certificate of training for Responsible Personnel (the "green card") under §4-104(b) of the Environment Article, unless waived.
Official sources
Common questions
What triggers a SWPPP inspection in Maryland?
Under the General Permit 20-CP for Construction Activity, a storm event of 0.25 inches or more triggers a post-storm inspection, within 24 hours (weekends count). Routine inspections: weekly + storm-triggered, or every 4 business days with no storm trigger (Tier II watersheds: twice per week).
Who can perform SWPPP inspections in Maryland?
Inspectors must hold a valid MDE certificate of training for Responsible Personnel (the "green card") under §4-104(b) of the Environment Article, unless waived.
Who administers the construction stormwater program in Maryland?
Maryland Department of the Environment (MDE) administers the NPDES construction stormwater program in Maryland under the General Permit 20-CP for Construction Activity.
What are the penalties for SWPPP violations in Maryland?
Federal Clean Water Act civil penalties can reach $68,445 per day per violation, and MDE 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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