Harrison County, MS Environmental Rules: Erosion Control (2026)

01 sets the permit trigger for the county's Drainage Management Site Plan (DMSP): it applies to any new single-family residential development, any new commercial, multi-family residential, institutional, industrial or utility development, and any land-disturbing activity greater than one acre. Older platted lots and non-platted single-family sites are exempt from a full plan unless the County Engineer requests one, and the code allows a scaled-down 'lesser plan' for qualifying individual residential properties, with the level of detail set by the County Engineer. The Engineer can also require a DMSP for any grading or excavation that would fill, obstruct, or otherwise alter a creek, stormwater channel or drainage facility, even outside the categories above, if adverse impacts are anticipated.

The plan itself must be sealed by a professional engineer registered in Mississippi and must include a topographic survey, existing sewer locations, projected runoff volumes, and a layout of the proposed drainage structures. Separately, an Encroachment Permit is required for any private entrance or utility work performed in the county road right-of-way, with the Utility Permit fee refunded if the work is completed as permitted within one year. This permit scheme applies only to unincorporated Harrison County, not to Gulfport, Biloxi, Long Beach, Pass Christian or D'Iberville.