New Castle County enforces stormwater management under Delaware's Sediment and Stormwater Program (7 Del.C. Chapter 40 and DNREC Delegation) administered by the New Castle Conservation District (NCCD). Projects disturbing 5,000+ sq ft or adding 5,000+ sq ft of impervious surface require an approved sediment and stormwater plan. Post-construction BMPs (bioswales, rain gardens, infiltration) are mandatory. NCC holds MS4 permit under Clean Water Act.
Stormwater management in New Castle County is administered through the Delaware Sediment and Stormwater Program, established under 7 Del.C. Chapter 40 and DNREC regulations (7 DE Admin. Code 5101), with delegation of plan review to the New Castle Conservation District (NCCD). Projects triggering review include any land-disturbing activity exceeding 5,000 square feet, any activity adding 5,000+ sq ft of new impervious surface, and any subdivision or major commercial site plan. Plans must include erosion and sediment control during construction plus post-construction stormwater management facilities. Delaware emphasizes Green Technology and Low Impact Development (LID), requiring bioswales, rain gardens, bioretention, infiltration trenches, permeable pavers, and similar BMPs over traditional detention ponds where feasible. Post-construction stormwater facilities must be maintained by the property owner or responsible HOA under a declaration of easement recorded with the deed. New Castle County holds an MS4 (Municipal Separate Storm Sewer System) permit under the federal Clean Water Act, administered by DNREC, and must address illicit discharges, public education, and water quality in the Delaware River, Brandywine Creek, Christina River, White Clay Creek, and Red Clay Creek watersheds. Chesapeake Bay Total Maximum Daily Load (TMDL) requirements apply to the western portions of the county draining to the Elk River via Maryland. Illicit discharge to storm drains (washing paint, oil, concrete, yard waste) is prohibited and strictly enforced.
Land disturbance without approved plan: stop-work order, $500 to $10,000+ per day under 7 Del.C. §4015. Sediment discharge to waters of the state: $1,000 to $25,000/day. Failure to maintain post-construction BMPs: corrective action order plus penalties. Illicit discharge: $500 to $10,000+ per incident.
New Castle County, DE
New Castle County permits gas and electric leaf blower use with no statewide or county ban. Operation hours align with the county noise ordinance (NCC Code C...
New Castle County, DE
Amplified sound in unincorporated New Castle County is regulated under NCC Code Chapter 22 (noise) and the county's special event permit process. Sound must ...
New Castle County, DE
Wilmington restricts overnight on-street parking 2 AM to 6 AM in posted zones and requires residential permits in many neighborhoods. Unincorporated New Cast...
New Castle County, DE
New Castle County requires electrical permits for Level 2 EV chargers. Delaware law (26 Del. C. §1018) preempts HOA bans on EV chargers. Public stations must...
New Castle County, DE
New Castle County requires a building permit for retaining walls over 4 feet measured from bottom of footing to top of wall. Walls supporting surcharge loads...
New Castle County, DE
New Castle County regulates fence materials through the Unified Development Code (UDC), primarily Article 40 (zoning). Wood, vinyl, composite, wrought iron, ...
See how New Castle County's stormwater management rules stack up against other locations.
Help us keep this page accurate. If you notice an error or outdated information, let us know.