Rivers
are dynamic systems, and there are many factors to be
considered before installing, rebuilding or removing a dam on
a river.
This section provides brief summaries of key
issues to be considered when deciding whether the Commonwealth
should remove the Baker and T&H Dams or whether it should
commit to keeping the dams in place. Issues discussed include:
Contaminated
Sediments
Fisheries
Flooding
prevention
Recreation
Historic resources
Aesthetics
Hydropower
Restoring
a natural ecosystem (please see below)
Industrial use
(please see below)
Contaminated
Sediments
The
sediments of most urban rivers like the Neponset can be
presumed to contain some level of contaminants as a legacy of
past pollution discharges. However, during the course of
studying fish passage alternatives, it has become apparent
that sediments in the
Lower
Neponset
River
are severely contaminated with PCBs in the area downstream of
Mother Brook (Hyde Park, Mattapan, Dorchester and
Milton
).
PCBs
in the river would be cleaned up in conjunction with any dam
removal project. In the absence of dam removal, the state is
not required to implement any cleanup activities and as of
this date has indicated no interest in pursuing a voluntary
cleanup. Combining river restoration with PCB cleanup will
help ensure that PCB cleanup is implemented relatively quickly
and in a manner sensitive to river aesthetics, recreational
uses and habitat considerations. More
on contaminated sediments...
Fisheries
Migratory
fish species, which for thousands of years swam up the Neponset
River
to lay their eggs, now have no access
to the river beyond the Baker Dam. These fisheries were a
critical food resource for Native Americans for at least
10,000 years, and were an important resource for early
European settlers as well. More
on fisheries...
Flooding
The
US Army Corps of Engineers and private consultants working for
the Riverways Program have conducted extensive hydraulic and
hydrologic evaluations of the Baker and T&H Dams to
evaluate flooding considerations. They have concluded that the
Baker Dam causes increased flooding and that the
T&H Dam serves no meaningful flood control purpose. They
have also concluded that removing the dams would reduce
flooding on the Lower Neponset. More
on flooding issues...
Recreation
Dam
removal would benefit several types of recreation along the
Neponset
River
including fishing, boating, and riverside recreation. Fishing
opportunities would be greatly expanded, boating which is
currently blocked by the dams would be safer and considerably
more enjoyable, and the safety of those recreating along the
banks of the river would be enhanced. More
on recreation…
Removing the dams would also change the
appearance of the river as seen from the perspective of those
recreating along the riverbanks. This, combined with the
opportunity to recreate bordering vegetated wetlands that were
flooded
when the dams were built, creates an opportunity to
re-engineer
the Neponset
River
channel to maximize its aesthetic value for those enjoying the
shoreline.
This is discussed further under "Aesthetics"
below.
Historic
Resources
The
Neponset
River
has a long and rich industrial history. The Baker and T&H
Dams themselves were built in the mid-1960s. The Baker Dam is
located within the boundaries of the Dorchester/Milton Lower
Mills Industrial Complex which is recognized by the National
Register of Historic Places. The Lower Mills Complex was added
to the National Register in recognition of the distinctive
architecture of many of the mill buildings, and in recognition
of the role Lower Mills played in influencing the course of
events in American History. The area around the T&H Dam
does not currently carry any particular historic designation.
Because
if its modern construction, the Baker Dam itself is not listed
as a “contributing element” to the Lower Mills Industrial
Complex. That said, the dam and mill pond do contribute to the
ambiance of the area, and thus any dam removal project would
incorporate measures to protect and document adjoining
historic resources and to more actively interpret the key role
of water power as the driving force behind the river’s
industrial period. More
on historic resources…
Aesthetics
Over
the last 30 years, pollution in the
Neponset
River
has been cleaned up, the buildings along its shores have been
converted to residential and commercial rather than industrial
use and its banks have been opened up and improved for
recreation. All of these changes have dramatically increased
the river’s importance as an aesthetically pleasing backdrop
that people can enjoy as they go about their daily business.
Without question, any dam removal project changes the
appearance of a river, though the change is often not as
dramatic as one might at first imagine. Aesthetic concerns are
also the most subjective issue that needs to be evaluated when
considering whether to keep or remove a dam. The Watershed
Association believes that dam removal presents a unique
opportunity to re-engineer the
Neponset
River
with the specific goal of enhancing the river’s aesthetics.
The
first and most challenging task in evaluating river aesthetics
post-dam removal, is to accurately visualize the change before
it occurs. More
on aesthetic considerations…
Restoring
a Natural Ecosystem
Decommissioning
and removing the dams creates the opportunity to restore a
substantial portion of the wetlands that once bordered the
river. Bordering wetlands add to the natural beauty of the
river, act as a nursery and habitat for a wide variety of fish
and wildlife, help hold back floodwaters and filter pollutants
from surface water.
Industrial
Uses and Hydropower
There
have been no meaningful industrial uses of the Baker Dam or
its impoundment since it was constructed in 1964. The Baker
Chocolate Company ceased its operations at Lower Mills in
1965. By contrast the impoundment created by the T&H Dam
was used by the Bay State Paper Company as a source for
industrial process water until the late 1990s. However, Bay
State Paper has closed its doors for good. Plans are in the
works for a shopping center on the site of the former paper
mill. It seems extremely unlikely that there might be any
future industrial uses associated with either of these dams.
More
on industrial use and hydropower…
January
2008
