|
Why Remove Dams?
The
process of dam-removal consideration often begins when a state inspector
investigates a dam and insists on repairs. The repairs often turn out to
cost far more than removal, so repair can only be justified if the dam
provides significant economic benefits. The other two main justifications
for dam removal are safety and ecological impacts. The average life
expectancy of a dam is 50 years, and a full one-quarter of all US dams are
now more than 50 years old. By the year 2020 that figure will reach 85
percent, according to
American Rivers. As development pressures around the country push
development into previously uninhabited floodplain areas, more and more
people find themselves living downstream from a dam. Dam breaches due to
structural flaws or large storms can cause serious property damage and loss
of life. In one recent year, dam and downstream repair costs resulting from
failures in 23 states totaled $54.3 million, according to the Association of
State Dam Safety Officials (ASDSO). In 2002,
ASDSO concluded that it would take approximately
$10 billion to rehabilitate the nation's most critical (high-hazard) dams
that are in need of rehabilitation.
In
terms of ecology, Bruce Babbitt, former Secretary of the Interior, said it
best in an
address to the Ecological Society of America in 1998: "The public is now
learning that we have paid a steadily accumulating price for these [dam]
projects in the form of: fish spawning runs destroyed, downstream rivers
altered by changes in temperature, unnatural nutrient load and seasonal
flows, wedges of sediment piling up behind structures, and delta wetlands
degraded by lack of fresh water and saltwater intrusion. Rivers are always
on the move and their inhabitants know no boundaries; salmon and shad do not
read maps, only streams." Dams can inhibit the ability of fish to move in
response to thermal stress, to address feeding needs, to escape other
environmental stressors, or to access upstream spawning habitat.
Occasionally, dams provide an environmental benefit by blocking the spread
of invasive or exotic fish species.
Ultimately, decisions to remove dams must reflect an understanding of the
ecological, economic, and cultural costs and benefits associated with
maintenance or removal of the structure. Design options that allow for the
partial removal of the structure or the reduction of ecological impacts
through means other than removal (e.g., modifications to the dam structure,
installation of fish passage, etc.) must also be considered in terms of
their costs and benefits. A comprehensive feasibility study helps to foster
a collaborative design process in which the full range of costs and benefits
associated with various stakeholder groups (e.g. landowners and conservation
groups, etc.) are considered.
How Are Dams Removed?
Due
to the potential for serious ecological impacts as well as major liability
issues resulting from dam removal, such projects should only be undertaken
under the direction of a professional engineer or consultant with experience
in lake and river ecology, dam structure, and river hydrology. A number of
state and federal agencies are responsible for regulating dams. Dams owned
by federal agencies are self-regulated, usually by the US Army Corps of
Engineers. Non-federal dams that produce hydropower are regulated by the
Federal Energy Regulatory Commission (FERC).
Non-federal dams that do not produce hydropower are regulated by the state
in which they reside. Often this state regulation is provided by the
state office of dam safety. Usually multiple permits are required for
dam removal or restoration projects.
Often
times, significant amounts of sediment accumulate above a dam that may have
to be dredged prior to dam removal to reduce downstream impacts. If the
sediments are contaminated, they must be treated as hazardous waste. Dams
are typically breached and removed using explosives and/or heavy machinery
such as cranes and backhoes. Erosion and sedimentation pollution control
measures are enacted to protect downstream areas during the project. After
the dam is removed, remediation of the surrounding area is usually required.
This may include riparian buffer planting, floodplain restoration, wetland
remediation, invasive plant removal, trash cleanup, streambank
bioengineering, and installation of fish habitat structures to restore fish
populations. Monitoring, both before and after removal, is an important part
of a dam removal project to determine the effects of the project on the
ecology of the area.
How Can Volunteers Get Involved?
Although dam removal design and engineering should only be undertaken by
professionals, volunteers can play an important role in the project.
Volunteers can advocate for dam removal and gather information in support of
the project. Volunteers can also be extremely helpful for monitoring,
riparian buffer planting, and stream cleanup. Local citizen support is
critical to the success of a dam removal project, and local volunteers are
the obvious choice for gathering stakeholder input and disseminating
monitoring results. The Pennsylvania Organization of Watersheds and Rivers (POWR)
has produced a
Citizen's Guide to Dam Removal and Restoration. The guide covers topics
on dam removal, restoration, and the monitoring that goes into each project.
Dam Removal Funding
F. X. Browne, Inc. Senior
Project Scientist Shandor Szalay will be speaking at the upcoming
Schuylkill Watershed Conference in March on “Planning for and
Implementing Dam Removal.” American Rivers and the National Oceanic and
Atmospheric Administration (NOAA) provide
financial and technical assistance for dam removal and fish passage projects
through their
Community-Based Restoration Program. Application deadlines are on April
1 and November 12 of each calendar year. Other sources of funding include
the
US Fish and Wildlife Fish Passage Program, the
Trout Unlimited Coldwater Conservation Fund, the
National Fish and Wildlife Foundation, the NRCS
Wildlife Habitat Incentive Program (WHIP), and various state agency programs.
F. X. Browne, Inc. can
assist with the application for and implementation of Community-Based
Restoration Program Projects, or other dam-related funding opportunities. F.
X. Browne, Inc. provides dam services including dam inspections, operation
and maintenance plans, emergency action plans, design plans, technical
specifications and contract documents, preparation of permit applications,
bidding assistance, and construction observation. F. X. Browne, Inc. also
performs dam removal feasibility studies. For more information, contact
info@fxbrowne.com.
References
American Rivers.
Dam Removal Today.
http://www.amrivers.org/index.php?module=HyperContent&func=display&cid=1720
American Rivers.
Dam Removal Toolkit
http://www.amrivers.org/drtk.html
Aspen Institute. 2002. Dam
Removal - A New Option For a New Century
http://www.aspeninstitute.org/bookdetails.asp?i=&d=129
Heinz Center.
2002. Dam Removal: Science and Decision Making.
http://www.heinzctr.org/publications.htm#Dam Removal
International Rivers
Network.
Reviving the World’s Rivers: Dam Removal.
http://www.irn.org/revival/decom/index.asp?id=/revival/decom/brochure/rrpt2.html
Pennsylvania Organization
of Watersheds and Rivers.
2004. Citizen’s Guide to Dam Removal Monitoring and Restoration.
http://www.pawatersheds.org/citizensguidetodamremovalandrestoration.pdf
Friends of the Earth.
1999. Dam Removal Success Stories: Restoring Rivers through Selective
Removal of Dams that Don't Make Sense.
http://www.foe.org/res/pubs/pdf/successstories.pdf
|
