Assabet River NWR Final CCP - U.S. Fish and Wildlife Service

Chapter 3: Refuge and Resource Descriptions
refuge into the Assabet River. The central and eastern areas of the
southern portion of the refuge are within the Sudbury River drainage
basin. Marlboro Brook drains from the southeastern portion of this section
of the refuge into Hop Brook, a tributary of the Sudbury River, just above
Stearns Millpond. The western portions of this section of
the refuge drain toward White Pond, which has no surface
outlet, but is thought to drain underground to Lake Boon
and thence to the Assabet River (U.S. Army 1995).
The water table under much of the refuge is shallow, as
indicated by the extensive swamps, bogs, and water-holes
found on the property. Groundwater discharge is thought to
be supplying much of the flow occurring through the
outwash plains underlying the lowlands of the site (U.S.
Army 1995). The poorly drained lowlands soils have
Taylor Brook: Photo by Marijke Holtrop
supported the establishment of extensive and diverse
wetland habitats, which include forested and shrubdominated
wetlands, bogs, emergent wetlands, open-water bodies in the
form of several lakes and ponds, an abandoned cranberry bog, and
scattered seasonally-flooded vernal pools (USFWS 1995).
Air Quality
The Massachusetts annual air quality report for 1999 (MADEP, 2000), and
the U.S. Environmental Protection Agency’s (USEPA) air quality planning
and standards web page (EPA, 2001), contain the most recent data
available for air quality in this area. The nearest data appear to be limited
to those from monitoring sites in the City of Worcester and the Town of
Stow. The Stow monitoring site has been located on the Assabet River
NWR since 1999, and prior to that time was located nearby on the Great
Meadows NWR in Sudbury.
The pollutants for which state-wide data are available are ozone (O 3 ),
carbon monoxide (CO), nitrogen dioxide (NO 2 ), lead (Pb), sulfur dioxide
(SO 2 ) and particulate matter (both 2.5 microns (PM2.5) and 10 microns
(PM10)).
The National Ambient Air Quality Standards (NAAQS) determined by
USEPA set the concentration limits that determine the attainment status
for each criteria pollutant. Massachusetts does not attain the public health
standard for two pollutants – ozone (O 3 ) for the entire state and CO in a few
cities (MADEP 2000), including parts of Worcester and Middlesex counties
within which the refuge is located (USEPA 2001).
There are two ozone standards based on two different averaging times, 1hour
and 8-hour. In 1999, there were 85 exceedances of the 8-hour standard
occurring on 22 days, and 5 exceedances of the 1- hour standard occurring
on 4 days on a state-wide basis. The 12-year trends for ozone readings in
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