Protection of instream flow is a critical aspect of managing our waters in a sustainable manner. While the benefits of flow regulation – hydroelectric power, flood control, water for numerous purposes – are obvious, the impacts often are not. In Vermont, we have focused much attention on maintaining adequate minimum flows to protect aquatic habitat and stream ecology, but other aspects of flow protection are equally important. In addition to minimum flows, the timing, frequency, duration and magnitude of both high and low flow events influence the physical and biological attributes of a stream or river. Changes in these characteristics can degrade habitat for fish and other aquatic organisms or affect their life cycles, result in increased erosion or sedimentation, and affect human use of rivers for recreation or other purposes.
Many of the larger water withdrawals in Vermont are used by ski areas for snowmaking. In recent years, many resorts have expanded their snowmaking systems. These projects usually include upgrades to the existing water withdrawal infrastructure to maintain conservation flows and construction of storage reservoirs so that water can be withdrawn during periods of high streamflow and used at other times when needed to make snow. The Agency of Natural Resources works closely with ski resorts to design systems that address the resorts' need for water while protecting the aquatic environment.
The U.S. Army Corps of Engineers operates five flood control projects in Vermont on tributaries of the Connecticut River. The Agency of Natural Resources is working closely with the Corps to ensure that water quality and aquatic habitat are protected at and below these projects while they still serve their primary purpose of providing flood protection.
There are approximately 85 hydroelectric generation facilities operating in Vermont and on waters bordering other states. Under state law, the Agency of Natural Resources is charged with ensuring that these projects are operated so that the state's rivers and lakes - which are public trust resources - continue to meet Vermont's water quality standards.
Water withdrawals in both streams and lakes usually require one or more permits. Act 250, Stream Alteration (in rivers), or Lake Encroachment (lakes and reservoirs that are public waters of Vermont) permits may be needed, as well as a permit from the U.S. Army Corps of Engineers. As with other projects requiring a federal permit, a Section 401 Water Quality Certification from the Agency will be required before the permit is issued.
For most types of water withdrawals (except those for snowmaking), the Agency has adopted a procedure that defines the standards and process used by the Agency during its review of project proposals. The procedure defines how the Agency will determine the minimum streamflow that is necessary to meet Vermont Water Quality Standards.
For snowmaking water withdrawals, the Agency has developed rules as directed by 10 V.S.A. §§ 1031-1032. The rules serve the same purpose as the Agency procedure but apply specifically to snowmaking projects.
Surface Water Gaging
The Streamflow Protection Program administers a cooperative agreement with the U.S. Geological Survey (USGS) to maintain and operate a number of stream gages in Vermont. These gages provide important streamflow data that are vital to the Agency of Natural Resources, other agencies, and the general public. Funding support provided by the Agency is critical to continued operation of these gages. USGS data in the National Water Information System are available on-line.
Additional Gaging Resources
Streamflow Protection Resources
- Agency Procedure for Determining Acceptable Minimum Streamflows - Procedure used to determine minimum streamflows for all activities (water withdrawals and hydroelectric projects) except snowmaking, adopted July 14, 1993.
- ANR Environmental Protection Rules: Chapter 16 - Water Withdrawals for Snowmaking - Agency rules used during regulatory review of snowmaking projects, effective date February 15, 1996.
- Guidance Document: Alternatives Analysis - Guidance on preparation of snowmaking alternatives analyses (1996)
- Fish Study Report (Mar 2009)
- Small Hydropower Report (Jan 2008)
- User's Guide to Vermont Dam Removals - Guidance on removing dams (2009)