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Stormwater Impaired Waters

New and Existing Discharges 
Lowland "Urban" Watersheds
Mountain Watersheds

As watersheds become more developed, the effects of stormwater runoff are being increasingly seen in our waters. Instead of infiltrating naturally into the soil, water quickly runs off of roofs and paved surfaces, picking up pollution and carrying it to waterways. Increased flows during storm events destabilize stream channels and put biological communities in jeopardy. ANR recognizes the importance of managing the quantity and quality of stormwater runoff, especially within Vermont’s stormwater impaired waters.

Fifteen of Vermont’s waters are listed as “impaired,” primarily due to urban stormwater runoff. These waters fail to meet the Vermont Water Quality Standards based primarily on biological monitoring data.

New and Existing Discharges

Expired permits in the impaired waters could not be renewed under the previously issued General Permits 3-9015 and 3-9010 but are now able to be renewed under the current General Permit 3-9050, which requires that an application to renew permit coverage be submitted no later than December 1, 2021.  In January 2022 letters were sent to landowners and permittees informing them of the requirement to renew the expired permit for their property.  The absence of a current stormwater permit may present a title encumbrance to involved properties.  For questions regarding the permitting of a site in an impaired watershed, permittees should contact the permit reviewer for their district.

Lowland “Urban” Watersheds

Once a water is listed as impaired, it is scheduled for the development of a Total Maximum Daily Load (TMDL). A TMDL is an EPA approved document that attempts to limit and allocate discharge loads among the various dischargers to impaired waters in order to assure attainment with water quality standards. The Department has issued EPA-approved hydrologic TMDLs for the twelve urban watersheds as listed below. For more information on the development of the TMDLs, see the Stormwater TMDL page.

Urban Stormwater Impaired Watersheds: The following urban watersheds are listed on the 2022 List of Priority Surface Waters (Part D) 

  • Allen Brook, Williston (map
  • Bartlett Brook, South Burlington (map)
  • Centennial Brook, Burlington and South Burlington (map
  • Englesby Brook, Burlington (map
  • Indian Brook, Essex (map)
  • Moon Brook, Rutland (map)
  • Morehouse Brook, Winooski (map)
  • Munroe Brook, Shelburne (map)
  • Potash Brook, South Burlington (map)
  • Rugg Brook, St Albans (map)
  • Stevens Brook, St Albans (map)
  • Sunderland Brook, Colchester and Essex (map

During 2008, VT DEC held meetings with a group of stakeholders known as the Stormwater Advisory Group or SWAG to discuss issues and strategies associated with implementing the stormwater TMDLs.  The culmination of this effort was the creation of an overall framework for remediation of the stormwater-impaired waters. Information from the meetings and final report are available on the SWAG page.

Remediation of the twelve urban stormwater-impaired waters has commenced through a combination of permits issued pursuant to Vermont’s federally delegated National Pollutant Discharge Elimination System (NPDES) permitting program. These permits include a reissued and enhanced NPDES permit for small municipal separate storm sewer systems (MS4s), which was issued on December 5, 2012.  Under the reissued permit, MS4 permittees must develop a Flow Restoration Plan for any stormwater impaired water to which they discharge. A computer-based best management practice decision support system (BMPDSS) was developed by TetraTech and is being used by VTDEC to help affected MS4 communities to identify different BMP options and associated costs.

In addition a NPDES RDA permit (General Permit 3-9030) has been issued to certain designated discharges not covered by the MS4 Permit in five of the urban stormwater-impaired streams.

Mountain Watersheds

Three mountain watersheds are listed as impaired primarily due to stormwater runoff on the 2022 EPA-approved 303d List of Impaired Waters (Part A). One of the previously listed watersheds, the North Branch of the Deerfield River in Dover, is no longer impaired for stormwater runoff following EPA’s approval of a revised 303(d) list in October 2020.  The watersheds in Warren and Killington listed below remain stormwater-impaired.  The mountain watersheds differ substantially from the remaining urbanized “lowland” watersheds in terms of density of development, geographic position, hydrology, impairment source, and land ownership. Based on these factors, the Department has concluded that use of the so-called “4b alternative,” a non-TMDL based alternative pollution control strategy, is the best implementation strategy. The Department is working with responsible parties developing watershed-specific WQRPs for the impaired mountain watersheds.

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