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Stormwater Directory

Delaware

Delaware Department of Natural Resources and Environmental Control

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Quick Summary

For most Delaware projects disturbing 1 acre or more, you need an NPDES Construction General Permit and a SWPPP. A locally approved Sediment and Stormwater Management Plan must be in place before you can file your NOI.

State-DelegatedVerified 2026-03

Construction Permit

Permit Document ↗
Permit Name
NPDES General Permit for Stormwater Discharges from Construction Activities (Permit No. DE0050164 / DER10000)
Threshold
≥ 1 acre of land disturbance (or < 1 acre if part of a larger common plan of development or sale)
NOI Lead Time
NOI must be submitted and acknowledged by DNREC before earth disturbance begins; no fixed calendar lead time is specified, but DNREC recommends allowing several weeks for processing
Application Method
Paper NOI form submitted to DNREC Division of Watershed Stewardship; ePermitting portal (myDNREC) for some applications — verify current method with agency
Fee
$200 application fee; annual compliance fee of $200 for sites < 5 acres, $400 for sites 5–10 acres, $600 for sites > 10 acres (verify current schedule with DNREC)
Permit Expires
February 16, 2028
Apply for Permit ↗

SWPPP Requirements

Permit Document ↗
SWPPP Required
Yes
PE Cert Required
No
Template Available
Yes
A Stormwater Pollution Prevention Plan (SWPPP) is required before earth disturbance begins. Delaware also requires a Sediment and Stormwater Management Plan (SSMP) approved by a local reviewing authority prior to permit coverage. DNREC provides SWPPP guidance documents. No PE stamp is required for the SWPPP itself, but the SSMP engineering design typically requires a licensed PE.

Inspection Requirements

Permit Document ↗
Frequency
At least every 7 days during active construction and within 24 hours after a storm event producing ≥ 0.5 inches of rainfall
Rain Trigger
Within 24 hours of a storm event producing ≥ 0.5 inches of rainfall
Inspector Qualification
Inspector must be knowledgeable about the SWPPP and BMPs; Delaware does not have a state-specific inspector certification, but CPESC (Certified Professional in Erosion and Sediment Control) or equivalent is recommended
Accepted Certifications
No state-specific mandatory cert; CPESC, CESSWI accepted; inspector must be knowledgeable in E&SC and SWPPP

Discharge Standards

Permit Document ↗
Turbidity Limit
No numeric NTU limit specified in the construction general permit; narrative standard applies — discharges must not cause or contribute to violations of Delaware's water quality standards
Delaware water quality standards (7 Del. Admin. Code 7201) prohibit discharges that cause aesthetic degradation, including discoloration and turbidity beyond natural background. Sites discharging to Outstanding Resource Waters (ORW) or other sensitive waterbodies may face more stringent conditions.

Post-Construction

DNREC ↗
Required
Yes
Delaware requires post-construction stormwater management through its Sediment and Stormwater Regulations (7 Del. Admin. Code 5101). Projects must demonstrate compliance with the Delaware Sediment and Stormwater Program, including permanent stormwater management facilities that meet volume and quality standards. Many New Castle County projects are subject to additional county-level requirements.

Impaired Waterbody / TMDL Requirements

Elevated Risk

Delaware is entirely within the Chesapeake Bay watershed; DNREC's construction stormwater permit references TMDL compliance requirements for sediment and nutrients. Projects near impaired Bay tributaries face enhanced erosion control expectations under Delaware's Sediment and Stormwater Program. The Chesapeake Bay TMDL (Phase 6 model) drives heightened scrutiny for nitrogen, phosphorus, and sediment loads statewide.

Program Contact

Contact Page ↗
Phone
(302) 608-5458
Email
DNREC.Stormwater@delaware.gov

State-Specific Notes

Delaware is unique in requiring a locally approved Sediment and Stormwater Management Plan (SSMP) as a prerequisite for NPDES coverage — applicants must work through a local plan reviewer (county or state) before filing the NOI. The state's Sediment and Stormwater Program regulations (7 Del. Admin. Code 5101) govern both the SSMP and construction activity standards. Delaware has adopted the Delaware Sediment and Stormwater Design Manual. Projects in the Inland Bays watershed may face additional nutrient management requirements.

Disclaimer: This information is provided for general reference only and may not reflect the most current regulatory requirements. Always consult the DNREC website and applicable regulations before beginning any construction activity.