Environmental Rules in New Castle County, DE (2026)
5 county-level rules, plus city-specific rules for 1 city in New Castle County, Delaware.
Verified from official government sources
Stormwater Management
New Castle County requires an approved sediment and stormwater management plan, built to state DNREC standards, before any grading, clearing or other land disturbing activity can begin in the unincorporated County.
New Castle County Stormwater Permit Rule
Some RestrictionsNew Castle County Code § 12.05.003
Except as provided in the Delaware Sediment and Stormwater Regulations, no person or entity may engage in any land disturbing activity until such person or entity has obtained an approved sediment and stormwater management plan. Lines and grades plans will not be approved for a parcel of land before approval of a sediment and stormwater management plan, except as exempted by the Delaware Sedime...
Erosion Control
New Castle County requires an approved sediment and stormwater management plan before any land disturbing activity begins, enforcing Delaware's DNREC erosion regulations through mandatory permits and site inspections across unincorporated parts of the county.
New Castle County Erosion & Sediment Control
Some RestrictionsNew Castle County Code § 12.05.003
Except as provided in the Delaware Sediment and Stormwater Regulations, no person or entity may engage in any land disturbing activity until such person or entity has obtained an approved sediment and stormwater management plan. Lines and grades plans will not be approved for a parcel of land before approval of a sediment and stormwater management plan, except as exempted by the Delaware Sedime...
Coastal Development
New Castle County's Unified Development Code blocks any new Heavy Industry (HI) zoning district from being created inside Delaware's Coastal Zone. Existing HI districts survive only where the parcel was already zoned M-3 under the county's former zoning map, and any use the state's Coastal Zone Act prohibits stays prohibited regardless of the underlying zoning designation.
New Castle County Bars New Heavy Industry in Coastal Zone
Significant RestrictionsNew Castle County Code § 40.02.242(D)
This district shall be permitted in coastal zones provided that any use prohibited by the Delaware Coastal Zone Act shall remain prohibited, and provided that such districts were zoned M-3 under the former New Castle County zoning maps. No new HI districts shall be created in a coastal zone.
Flood Zones
New Castle County requires a floodplain development permit from the Department of Land Use before any construction, fill, or land disturbance in a special flood hazard area.
New Castle County Floodplain Permits
Significant RestrictionsNew Castle County Code § 40.10.311
It shall be unlawful for any person or entity to begin construction or other development which is wholly within, partially within, or in contact with any identified special flood hazard area, including but not limited to: subdivision of land, filling, grading, or other site improvements and utility installations... until a permit is obtained from the Department of Land Use.
Flood Elevation Requirements
New Castle County's Building Code amendment to IBC Section B1612.2 requires the lowest floor or crawlspace of new construction to sit at or above base flood elevation plus 18 inches of freeboard.
New Castle County: Base Flood Elevation Plus 18 Inches
Some RestrictionsNew Castle County Code § 6.04.002 (amending IBC § B1612.2)
Section B1612.2, Design and construction, is amended at the end of the paragraph by adding the phrase "and shall have the lowest floor or crawlspace elevated to or above the base flood elevation plus 18 inches".
Environmental Rules by City in New Castle County
1 cities in New Castle County have their own environmental rules rules. Each link goes to that city's dedicated page with code citations.
All New Castle County ordinances
See every category we cover for New Castle County: parking, noise, fences, fires, animals, pools, and more.
New Castle County Ordinance Hub →