“Dredging Windows” Are Topic of Scoping Meeting for Pilot Project"
May 22, 2018
By Marie Zhuikov
It can’t happen just any old time. Removing sediment from or adding it to
harbors to help ships pass or for construction projects is regulated by state
and federal rules designed to lessen impacts to the plants and animals living
in both marine and fresh water.
“We used to call them fish windows,” said Gene Clark, Wisconsin Sea Grant
coastal engineer. “But we’ve learned that other species can be affected by the
timing of dredging as well – things like mussels, amphibians and wild rice.
It’s not just a fish window, it’s an environmental window for dredging.”
These timing windows were first created almost 50 years ago, spurred by the
passage of the National Environmental Policy Act in 1969. They hardly ever
change and are enforced through the permitting process by the U.S. Army Corps
of Engineers and state departments of natural resources. The designations of
these windows were set by natural resource experts, however specific
science-based data to help them was lacking.
According to a white paper on dredging windows in the Duluth-Superior
Harbor, a number of new scientific tools are now available to “evaluate the
specific impacts of dredging, to more accurately monitor the biological
integrity and specific biological functions of different parts of our harbors,
and to assess changes due to season variation. In addition, new engineering
technologies have resulted in new dredging methods and construction options to
reduce the impacts of the dredging process, as well as in-water facilities
maintenance and fabrication.”
Bringing dredging windows up to date was one of the most important issues
identified by harbor stakeholders when asked where they thought Sea Grant could
make a difference, Clark said. At stake is money and time, not to mention the
wellbeing of the environment.
“The timing of the dredging windows can be very strict, and they can make
projects more costly,” said Clark. “The problem doesn’t just affect our harbor.
All dredging projects on the Great Lakes have this issue, too.”
Clark believes that with more information about where critical habitats are
in the harbor and when important wildlife activities are going on, such as fish
spawning, money can be saved on behalf of taxpayers and the contractors.
Clark has teamed with Dale Bergeron, Minnesota Sea Grant maritime extension
educator, and members of the Duluth Seaway Port Authority to work on the issue.
They have been working for a year to write a white paper, develop a process for
deciding what studies are needed, and provide a template for studies in other ports.
“Our goal is to facilitate discussions between the regulatory
agencies, the U.S. Army Corps and the contractors,” Clark said. They also plan
to work with academic researchers to find funding for the studies.
One activity is taking place next week on May 30. A select group of people
from the Duluth-Superior area have been invited to participate in a scoping
meeting to conduct a “Science-based Review of Environmental Windows for
Dredging and In-water Construction in the Duluth/Superior Estuary and Harbor.”
On the agenda is the history of dredging windows, and defining biological
issues such as locations of high- and low-productivity areas and the impacts of
seasons and climate variability, and discussion of new technologies that are
available for dredging and reducing turbidity. The resulting tasks will take
the form of a pilot project, for which funding will be sought.
“Perhaps in a couple of seasons, we’ll have enough information so we can
actually make a difference in when dredging windows are set, and potentially
save the corps some money, save the contractor money and save some angst on
behalf of the permitting agencies,” Clark said.
