Sediment and Stormwater

The DNREC Sediment and Stormwater Management Program operates within the Division of Watershed Stewardship’s Conservation Programs Section. The program employs a comprehensive approach to sediment control (both during and after construction) and stormwater management that includes monitoring of stormwater quantity and water quality control.

Notice: The Sediment and Stormwater Program has released new and revised regulatory guidance documents for public review.

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The Sediment and Stormwater Program was created by the Delaware General Assembly in 1978 (7 Del. Code, Chapter 40, Erosion and Sedimentation Control). It oversees activities governed by Delaware’s Sediment and Stormwater Regulations (7 DE Admin. Code 5101).

Program responsibilities include:

Sediment control and inspection during construction
Post-construction inspection of permanent stormwater facilities
Stormwater quantity and water quality control
Education/training relating to stormwater

For more information, please contact the Sediment and Stormwater Program at 302-608-5458.

New and Revised Regulatory Guidance Documents

The Department of Natural Resources and Environmental Control (DNREC) Division of Watershed Stewardship Sediment and Stormwater Program has released new and revised regulatory guidance documents for public review. These documents support Regulation No. 5101 Sediment and Stormwater Regulations (DSSR), as set forth at 7 Del.C. §4006(h) and (i).

The new and revised regulatory guidance documents, and brief descriptions follow:

Regulatory Guidance Memo 6 (RGM-6): Extended Detention RPv Credit and Design Procedures, provides background on the regulatory requirements for managing RPv credits, defines how RPv credit is quantified, and establishes procedures for demonstrating compliance and RPv credit when utilizing extended detention BMPs.

DURMMv2.6 (EXCEL) combines the two current versions of DURMMv2.51 into a single workbook, modifies the computation for submerged gravel wetland, reduces the number of BMPs computed in series, and provides additional tools to demonstrate compliance for extended detention BMPs in accordance with RGM-6.

Note: A webinar was held on May 18 to demonstrate DURMM updates. View a recording of the webinar. Responses to comments received following the webinar are available for review.

Summary Table for Site RPv Compliance (EXCEL) has revised notes to reference DURMMv2.6.

The proposed regulatory guidance document revisions are published in the July issue of the Delaware Register of Regulations. A public hearing will not be held unless the DNREC Secretary receives a meritorious request for a hearing by July 16, 2026.

If a meritorious request for public hearing is not received, RGM-6 and DURMMv2.6 will become effective on August 1, 2026. Sediment and Stormwater Management plans submitted for review in accordance with Step 2 or Step 2/3 prior to August 1, 2026, will not be required to submit revised DURMM computations; however, revised computations using DURMMv2.6 will be accepted.

For more information, please contact Bonnie Arvay at Bonnie.Arvay@delaware.gov or 302-608-5458.

Delegated Agencies

There are delegated agencies in all three Delaware counties, and in several municipalities who perform sediment and stormwater services including plan review, construction inspection, and maintenance inspection.

NPDES Construction General Permits

Delaware’s Regulations Governing the Control of Water Pollution provide for a general permit under the National Pollutant Discharge Elimination System (NPDES) for controlling stormwater discharges from construction sites.

For permit coverage, construction activities with land disturbing activities of 1 acre or more must submit a Notice of Intent (NOI) prior to plan approval and agree to comply with requirements outlined in the NPDES General Permit for Stormwater Discharges from Construction Activity, also known as the Delaware Construction General Permit or CGP. Permit coverage is required until conditions of terminating permit coverage are met.

General Permit and Regulations

Delaware Construction General Permit (Effective March 11, 2026)

Fact Sheet for the Delaware Construction General Permit

Special Conditions for Stormwater Discharges from Construction Activities (7 DE Admin. Code 7201 Part 2)

Electronic Notice of Intent (eNOI)

The eNOI System is an online tool to review, submit or manage NOIs or NPDES construction permits.

eNOI User Guide

List of Notices of Intent

Regulatory Guidance Documents

The Erosion and Sediment Control Handbook provides background information on erosion and sedimentation, information on Delaware’s regulatory program and standards and specifications for erosion and sediment control. The standard details to be used on Sediment and Stormwater Plans are also available for download.

The Post Construction Stormwater BMP Standards and Specifications contains design guidelines, construction guidelines and maintenance recommendations for the various permanent Best Management Practices (BMPs) intended for both quality and quantity management of stormwater runoff.

The Standard Guidelines for Operation and Maintenance of Stormwater BMPs summarizes the maintenance items and frequency from the Post Construction Stormwater BMP Standards and Specifications into a single document. Maintenance review checklists for a selection of those practices are also included.