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.

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.

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.

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New and Revised Regulatory Guidance Documents

The Sediment and Stormwater Program has released new and revised regulatory guidance documents for public review. These documents support the Sediment and Stormwater Regulations (7 DE Admin. Code 5101).

The Delaware Erosion and Sediment Control (ESC) Handbook Section 3.6.1 has been revised to modify waste management practices and to align with the 2022 Federal National Pollutant Discharge Elimination System Construction General Permit.

Sediment and Stormwater management plan applications have been revised to reflect the increase in the plan review fee for state and federal projects, approved with the signing of HB 175 in June 2025, and update the included Delaware ESC Handbook details, where applicable.

• Detailed Plan Application
• Agriculture Structure Construction
• BMP Construction and Retrofit
• Demolition
• Minor Bridge and Culvert Construction
• Minor Linear Disturbances
• Non-residential Construction (less than 1 ac)
• Poultry House Construction
• Residential Construction (less than 1 ac)
• Residential Construction (greater than 1 ac)
• Sidewalk, Trail, or Other Linear Impervious Surface
• Stormwater Facility Maintenance
• Tax Ditch Maintenance

The proposed new and revised regulatory guidance documents are published in the December 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 December 16, 2025. For more information, please contact Bonnie Arvay, at 302-608-5458 or bonnie.arvay@delaware.gov.

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NPDES Construction 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

Fact Sheet for the Delaware Construction General Permit

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

Regulatory Guidance Documents

Delaware Erosion and Sediment Control Handbook

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.

Post Construction Stormwater BMP Standards and Specifications

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.

Standard Guidelines for Operation and Maintenance of Stormwater BMPs

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.

Regulatory Guidance Memoranda

RGM-1: NOAA Rainfall Distributions (Version 2)

RGM-2: Procedure for Conducting a Downstream Analysis

RGM-3: Rescission of Appoquinimink River Watershed Stormwater Management Plan Standards and Criteria for Stormwater Control

RGM-4: Discharge Notification

RGM-5: Standard Plan Curve Number Comparison

Related Topics:  drainage, drainage and stormwater, erosion, sediment, sediment and stormwater, stormwater, watershed stewardship