Stormwater Regulations in DC, Maryland, Virginia & Delaware

Stormwater runoff – the water that flows over streets, parking lots, lawns, and construction sites after a rainstorm – can carry pollutants like oil, sediment, heavy metals, and bacteria into nearby waterways. If unmanaged, this runoff contributes to flooding, erosion, and water pollution. But when properly managed, stormwater can be redirected or treated to support water quality, recharge aquifers, and reduce damage to infrastructure.

Whether you’re a developer, property manager, business owner, or local government agency, understanding the stormwater regulations that apply to your property or project is critical. Every state has its own rules designed to mitigate the environmental impact of land use and development.

Here’s a breakdown of stormwater regulations in Virginia, Maryland, Washington, DC, and now Delaware.

📞 Need expert help navigating regional stormwater regulations? Contact iSTORMWATER at (410) 231-3455.

Virginia: Consolidated Oversight via the VESM Regulation

Virginia’s Department of Environmental Quality (DEQ) enforces stormwater rules under the Virginia Erosion and Stormwater Management (VESM) Regulation. As of July 1, 2024, this framework unifies stormwater and erosion control standards for greater clarity and compliance efficiency.

Who’s Affected?

• Construction firms disturbing 1 acre or more
• Industrial facilities discharging into MS4 systems or waters of the state
• Municipalities operating MS4s
• Property owners with redevelopment or land use changes

Key Requirements

• Construction General Permit (CGP) with mandatory turbidity monitoring
• Stormwater Pollution Prevention Plan (SWPPP)
• MS4 program compliance for local governments
• Exemptions for some agricultural operations

Maryland: Environmental Site Design is the Standard

Maryland’s stormwater program, administered by the Maryland Department of the Environment (MDE), is guided by the Stormwater Management Act of 2007. It emphasizes Environmental Site Design (ESD) to the Maximum Extent Practicable (MEP), requiring projects to mimic natural hydrology.

Who’s Affected?

• Developers
• Institutional and commercial property owners
• Local government agencies
• Redevelopment projects of any scale

Key Requirements

• ESD practices such as bioretention cells, vegetated swales, and permeable paving
• Stormwater management plans approved by local agencies
• Minimum runoff volume treatment for both new and redevelopment sites

Maryland places significant authority with local Soil Conservation Districts and Planning Departments, making early coordination essential.

Washington, DC: Urban-Focused Stormwater Controls

DC’s Department of Energy & Environment (DOEE) has one of the most stringent post-construction stormwater management programs due to its highly urbanized landscape.

Who’s Affected?

• Developers and property managers of commercial, institutional, or multi-family projects
• Owners/operators of sites disturbing 5,000 sq. ft. or more
• Sites undergoing substantial improvement or redevelopment

Key Requirements

• Retain stormwater volume from 1.2 inches of rainfall
• Implement green infrastructure such as rain gardens, green roofs, and underground cisterns
• Participate in the Stormwater Retention Credit (SRC) trading program when on-site retention isn’t feasible

Delaware: New Castle to Sussex, Statewide Compliance Is Required

Delaware’s Department of Natural Resources and Environmental Control (DNREC) enforces stormwater and sediment control programs through its Division of Watershed Stewardship. The state aligns with federal NPDES regulations but has local oversight through Conservation Districts.

Who’s Affected?

• Construction projects disturbing 5,000 sq. ft. or more
• Industrial and commercial facilities
• MS4 operators in urbanized areas (including New Castle County and Dover)

Key Requirements

• Sediment and Stormwater Program Plan approval prior to land disturbance
• Stormwater BMP design following Delaware’s Technical Document (2020 update)
• Post-construction BMP maintenance plans required for all regulated projects
• MS4 permit coverage for public agencies in urban areas

Delaware emphasizes both water quality and quantity control, especially near sensitive ecosystems like the Chesapeake Bay watershed and Inland Bays.

Local Jurisdictions May Impose Stricter Stormwater Rules

While state agencies like DEQ (VA), MDE (MD), DOEE (DC), and DNREC (DE) provide the regulatory framework, individual municipalities, cities, and counties often enforce their own stormwater regulations – sometimes with stricter requirements. Local governments may:

• Require additional permits or plan reviews
• Impose stricter performance standards or retention requirements
• Mandate specific types of best management practices (BMPs)
• Conduct their own inspections and compliance audits
• Enforce maintenance agreements for stormwater facilities

For example:

• Fairfax County, VA and Montgomery County, MD have extensive MS4 programs and their own design manuals.
• Prince George’s County, MD has pioneered green infrastructure incentives.
• Wilmington, DE enforces local stormwater utility fees tied to impervious surface area.

Because of this patchwork of overlapping rules, it’s essential to consult both state and local agencies when planning a construction project, facility expansion, or redevelopment.

Stormwater Compliance Solutions for Every Industry

iSTORMWATER supports a wide range of clients in navigating stormwater compliance – not just developers. We work with:

• Property managers and building owners
• Government and municipal agencies
• Healthcare, education, and retail facilities
• Industrial and manufacturing sites
• Contractors and engineering firms

Whether you’re maintaining an existing stormwater system or preparing for a new construction or redevelopment project, our team can help you stay compliant, avoid costly violations, and ensure long-term sustainability.

✅ Upfront site surveys
✅ Permitting support and coordination
✅ Maintenance and repairs
✅ Annual inspections and documentation

Schedule a consultation with iSTORMWATER today – call (410) 231-3455.