Stormwater Management: Gaithersburg vs Rockville
How do stormwater management rules compare between Gaithersburg, MD and Rockville, MD?
Gaithersburg and Rockville have similar restriction levels.
Gaithersburg, MD
Montgomery County
Gaithersburg enforces stringent stormwater management requirements under its NPDES Municipal Separate Storm Sewer System (MS4) permit administered through Montgomery County DEP and the WSSC service area. All development and redevelopment projects disturbing 5,000 square feet or more must implement environmental site design to the maximum extent practicable. Residential properties must manage stormwater runoff on site.
View full Gaithersburg rules →Rockville, MD
Montgomery County
Rockville holds a Municipal Separate Storm Sewer System (MS4) permit from the Maryland Department of the Environment and enforces stormwater management requirements for all development that disturbs 5,000 square feet or more. Stormwater management plans must conform to the latest MDE Design Manual. The city operates under National Pollutant Discharge Elimination System (NPDES) requirements to protect local waterways.
View full Rockville rules →Key Facts Comparison
| Fact | Gaithersburg | Rockville |
|---|---|---|
| Permit Program | NPDES MS4 | - |
| Disturbance Threshold | 5,000 sq ft triggers requirements | 5,000 sq ft or 100 cu yd |
| Design Standard | Environmental Site Design (ESD) | MDE Stormwater Design Manual |
| County DEP | (240) 777-7770 | - |
| Public Works | (301) 258-6370 | - |
| Permit Type | - | MS4 under NPDES |
| Preferred Approach | - | Environmental site design (ESD) |
| Contact | - | 240-314-8567 |
Highlighted rows indicate differences between cities.
Gaithersburg FAQ
When is stormwater management required in Gaithersburg?
Any development or redevelopment project disturbing 5,000 square feet or more must implement environmental site design stormwater management practices. This applies to new construction, additions, and significant grading.
Who reviews stormwater plans in Gaithersburg?
Montgomery County Department of Environmental Protection reviews stormwater management plans under Chapter 19 of the County Code, even for projects within Gaithersburg city limits.
Can I discharge pool or wash water into storm drains?
No. Discharging pool chemicals, wash water, or any non-stormwater substance into storm drains is prohibited under the MS4 permit and can result in fines up to $10,000 per day.
Rockville FAQ
When is a stormwater management plan required in Rockville?
A stormwater management plan is required for any development that disturbs 5,000 square feet or more of land area or moves 100 cubic yards or more of soil. Plans must conform to MDE's Stormwater Design Manual.
What is environmental site design?
ESD uses techniques like rain gardens, bioretention, permeable pavement, and green roofs to manage stormwater runoff at the source. Rockville requires ESD to the maximum extent practicable for new development.
Who maintains private stormwater facilities?
The property owner or designated maintenance entity is responsible. The city inspects private stormwater facilities and issues correction notices for non-compliant systems.
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