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 include:

• Regulatory Guidance Memo 1 (RGM-1) has been revised to RGM-1v.2 to require NOAA rainfall distribution curves to be used in stormwater computations.
• RGM-4 provides procedures for notification of stormwater discharges to DelDOT.
• RGM-5 provides a computational tool to assist applicants in confirming that Standard Plan criteria are met.
• DURMMv2.6 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 determine compliance for extended detention BMPs.
• Summary Table for Site RPv Compliance has revised notes to reference DURMMv2.6.

The DNREC Sediment and Stormwater Program hereby provides notice of these regulatory guidance documents, pursuant to 7 Del.C. §4006(i), which incorporates the provisions of 7 Del.C. §6004. A public hearing will NOT be held unless the Secretary receives a meritorious request for a hearing within 15 days of date of this notice, ending November 16, 2025. A request for a public hearing shall be in writing and show familiarity with the regulatory guidance document and provide a reasoned statement of the regulatory guidance document’s probable impact.

These documents are noticed in the November 2025 Register of Regulations and are available for review at dnrec.delaware.gov/watershed-stewardship/sediment-stormwater.

Questions regarding the revised regulatory guidance documents may be directed to Bonnie Arvay, bonnie.arvay@delaware.gov.

Related Topics:  permitting and regulation, public notice, regulatory guidance, sediment and stormwater, watershed stewardship