Oxbow NWR Final CCP - U.S. Fish and Wildlife Service

Groundwater Resources
Chapter 3: Refuge and Resource Descriptions
The groundwater hydrology of the refuge and the surrounding area is
largely defined by topography and the distribution and saturated thickness
of high conductivity glacial outwash deposits within the Nashua River
valley and low conductivity glacial till deposits in the upland areas. This
distribution of unconsolidated sediments results in steep hydraulic
gradients in the upland areas with a general flattening of the water table
within the regions of glacial outwash. Maintaining the base flow of the
rivers and streams, groundwater flows from hills toward valleys, and
discharges into streams, rivers, wetlands, and ponds. An extensive sand
and gravel glacial outwash aquifer underlies most of refuge on the former
North Post, the eastern portion of Main Post, and the northeastern corner
of South Post, in addition to contiguous areas in adjacent towns (U.S. Army
1995).
The most productive parts of the aquifer (the high yield aquifer) are
associated with the Nashua River and its tributaries. The glacial outwash
deposits present in these high transmissivity areas are major sources of
potable water for Devens and the towns of Shirley and Ayer. In most areas
where the glacial outwash aquifer is not present, fractured bedrock
resources supply water to single-family domestic wells (U.S. Army 1995).
The Devens water supply is provided by the McPherson Well on North
Post, the Grove Pond Wellfield in the northeastern corner of Main Post,
and the Patton and Sheboken Wells located, respectively, northeast and
southwest of the mirror lakes in the southern portion of Main Post.
Groundwater in the vicinity of Devens is designated Class I groundwater
by the Massachusetts Department of Environmental Protection (MADEP)
and is considered to be a potable source of water. In general, the water
within the main aquifer of Devens is moderately hard, requires minimal
treatment and, based on tests at individual supply wells, and has met all
MADEP water quality standards, with the exception of those for sodium
(U.S. Army 1995).
The town of Ayer operates two wells on the southern shore of Grove Pond,
to the east of the Devens Grove Pond Wellfield. In the past, these wells
have functioned as a backup to Ayer’s main water supply wells, which are
located adjacent to Spectacle Pond in Ayer, east of Devens. The total rated
capacity of the two wells is approximately 2 million gallons per day (MGD)
(U.S. Army 1995).
The Shirley Water Supply District maintains two wells in the vicinity of the
refuge. The Patterson Road Well, located in Shirley along Morse Brook
due west of the McPherson Well, supplies approximately 225,000 gallons
per day (GPD). Further west, the Catacoonamug Well supplies
Comprehensive Conservation Plan
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