Environmental Rules in Montgomery County, MD (2026)

Montgomery County DEP - Stormwater Management Program

Polluted runoff (commonly called stormwater runoff) carries pollution and trash as it flows into our streams, lakes, ponds and rivers, making them unhealthy. Stormwater Management is the process where we slow, store, or allow stormwater to soak into the ground to help reduce the amount of pollution entering our waterways. Montgomery County uses above and below ground structures (we call them st...

Montgomery County Code § 19-2

(a) Except as provided in this Chapter, a person must not engage in any land-disturbing activity without first obtaining a permit. (b) A permit is not required under this Chapter for: (1) any minor land-disturbing activity that: ... (B) involves less than 100 cubic yards of earth movement; (C) disturbs less than 5,000 square feet of surface area ... and (E) is promptly stabilized to prevent ero...

Montgomery County Code § 19-37

A person must not engage in any land-disturbing activity within the floodplain district or within 25 feet of any boundary of the district unless the Department issues a floodplain district permit, except as provided in this section.    (b)   A floodplain district permit is not required for:       (1)   Any minor land-disturbing activity that:          (A)   Disturbs less than 5000 square feet o...

COMCOR 19.45.01.04.A.6 (Floodplain Regulations, adopted under Montgomery County Code § 19-45)

Developments when approved, must have the elevation of the lowest floor, as defined in the Code, of all new or substantially improved structures at or above one (1) foot above the elevation of the One Hundred (100) Year Flood. Basements, as defined in the Code, are prohibited in the One Hundred (100) Year Floodplain.          7.   Design, Anchoring, and Materials - All construction when approve...