Lamoille County Planning Commission


3 Acre Stormwater Permitting Rule

3 Acre Stormwater Permitting Rule

Per Act 64 (Vermont Clean Water Act) and Lake Champlain TMDL Plan requirements, the Vermont Department of Environmental Conservation (DEC) is required to adopt a new rule and general permit for stormwater management from “three-acre sites.” Three acre sites are defined by DEC as "existing sites with three or more acres of impervious surface that lack a stormwater permit based on the 2002 Stormwater Management Manual." The 3 Acre Rule was adopted by DEC in February of 2019. It  includes standards applicable to the general permit, as well as all stormwater permitting. Please see below for resources on the 3 Acre Stormwater Permitting Rule.

For more information on the Stormwater General Permit please visit DEC's Stormwater Permitting Rule Update Page.


For information on ARPA funding opportunities for properties that fall under the 3 Acre Stormwater General Permit, please visit the VT DEC “Treating Stormwater Runoff” page here.


The Vermont DEC Stormwater Program has separate Sections for Operational and Construction permitting. Please click here for the Stormwater Districts Contact page. There is a district contact map for operational permitting and a separate district contact map for construction permitting.  

3 Acre Rule Permit Deadlines Timeline

The initial permit application will be due on a staggered schedule, starting 12 months from the effective date of the General Permit and will extend through early 2023, however previously permitted “three-acre sites” will apply for permit coverage prior to expiration of their existing permits starting with the effective date of the general permit. As part of the initial application (Initial NOI) landowners will need to provide basic project information. 

Landowners will then have 18 months to complete an engineering analysis to determine a "best-fit" stormwater system that uses modern stormwater treatment practices to filter, store, or soak up runoff.

Once the stormwater system plan is approved, landowners will have up to five years to install the new stormwater systems. 

The Agency will notify property owners affected by the requirements for "three-acre sites" directly and provide information on the application process.  This notification will affect roughly 700 projects, including 8,000 landowners.  Property owners in the Lake Champlain, Lake Memphremagog, and stormwater-impaired watersheds will be notified.  Properties outside those watersheds will be notified at a later date.  The Agency will also provide affected property owners a process for requesting reconsideration of a "three-acre site" designation.