Natural Resources

Groundwater

Groundwater provides the primary supply of potable water for most of the region. Despite its high resource value, it remains a poorly understood resource. Groundwater moves beneath the ground through aquifers, which are underground water-bearing formations of sand, gravel and fractured rock. Due to Vermont's geology, groundwater is often unpredictable as it travels through a maze of cracks in bedrock formations. It can infiltrate rock fractures and travel quickly in unknown directions for long distances, or break out to the surface in a short distance.

Groundwater occurs in the unconsolidated sediment of streams and buried valleys and in bedrock fractures.  While groundwater potential in areas of unconsolidated sediment is generally favorable, wells producing water from rock fractures usually have low yields (ranging from two to fifteen gallons per minute).  The region's mountains and uplands have either exposed bedrock or bedrock covered by a thin layer of glacial till with low permeability; in these areas bedrock fractures are the primary source of groundwater.

groundwater

The Vermont Department of Environmental Conservation (DEC) maintains a comprehensive groundwater management program and puts groundwater in trust for the public now and for future generations. The three main components are:

• Information or the science and mapping of groundwater resources, including the location and movement of groundwater, its use, contamination, remediation, and protection.
• Regulation: classifying types of groundwater and developing and implementing rules that govern or permit activities that may impact groundwater.
• Communication or outreach to provide help and guidance to towns, municipalities, and the public through partnerships with EPA, USGS, VGS, VRWA, and other groups to encourage and support protecting groundwater resources.

Technical assistance for municipalities is available through DEC to help towns analyze the groundwater potential within town boundaries.  The towns of Londonderry and Rockingham have undertaken such studies.  These types of studies are especially important in the siting of landfills and in planning for village centers that need a public water supply to accommodate village expansions.

By statute, all groundwater of the state is classified as Class III water unless reclassified by the Secretary of ANR under provisions of 10 V.S.A., Chapter 48 Groundwater Protection, Subchapter 2, § 1394. The groundwater beneath the Windham Solid Waste Management District landfill in Brattleboro has been reclassified to Class IV, as has the Southern Windsor/Windham Counties Solid Waste Management District landfill in Rockingham.  All other groundwater in the region remains Class III. 

groundwater quality

Groundwater generally moves through soils very slowly.  As a result, the cleansing processes that occur through dilution and movement in surface water do not take place underground.  When an aquifer becomes polluted, simply removing the source of contamination does not clean up the groundwater. A contaminated aquifer may remain polluted for many years, and practically forever in some cases. Groundwater occurring in rock fractures is highly susceptible to contamination. While unconsolidated sediment can usually filter out organic pollution contained in water, the same water can travel for miles through rock fractures without appreciable purification.  Once contamination occurs, control and abatement are extremely difficult.  Consequently, one of the most important challenges of environmental planning is to prevent pollutants from entering rock fractures. 

Potential groundwater pollutants include septage from improperly designed or malfunctioning septic tanks and leaching fields, leakage from underground gas and oil tanks, from commercial fuel, cooling and supply pipes, and from improper disposal of chemicals, both stable and radioactive. Public Community and Non-Transient, Non-Community Water Systems must have an approved Source Protection Plan (SPP). This Plan addresses the actions the public water system will perform to minimize the contaminant risks to their drinking water supply source(s). The water system is required to submit an updated plan to the Division every three years for approval.