The current 2008 New Hampshire Stormwater Manual (Manual) has been updated in response to evolving science and available technologies for stormwater management as well as new and increasing local, state, and federal permit requirements. The updated 2025 Manual has been developed through a partnership between the New Hampshire Department of Environmental Services (NHDES) and the University of New Hampshire Stormwater Center (UNHSC), with consulting assistance from Comprehensive Environmental, Inc. (CEI). The 2025 Manual can be found on the UNH Stormwater Center website.
On March 5, 2025, representatives from NHDES, UNHSC and CEI will host a public informational session to outline the collaboration process with stormwater professionals, provide an overview of the 2025 Manual, and highlight the significant changes from the 2008 Manual. You can find more detailed information on the “Updated” New Hampshire Stormwater Manual & Informational Session on the NHDES website. This public informational session will be recorded and located on the UNH Stormwater Center website.
If you have any questions or require additional information, please contact Deborah Loiselle at 603-271-1352 or deborah.s.loiselle@des.nh.gov.