[Music playing]
Faith: So we're standing really close
to where the dam was removed, the
Simkins dam on the Patapsco River,
close to Ellicott City in Maryland.
It's one of the four dams on the
Patapsco, two of which have been taken
out recently. I have some of the people
standing here with me that were key to
having this happen. Serena, what's some
of the history here, why this dam could be removed?
Serena: We're actually, like you said,
there are found dams on the Patapsco.
The dam upstream of this, the Union
dam, was actually under consideration
for removal by the Maryland Department
of Natural Resources. It was the only
dam that was reached by hurricane
Agnes, in the 1970s, so that particular
one was one that had already been in
the works for several years. Downstream
of this, the Bloede dam, is also owned
by the Department of Natural Resources
and there have been about ten people
that have died at that structure. So
it's a real safety hazard. So the park
and DNR, have a vested interest in
seeing that dam removed as well.
So really what you had was this
privately owned dam in the middle of
it. Luckily, the mill associated with
the dam, which most recently
manufactured recycled cardboard,
actually burnt mostly down in 1995. So
the dam was currently serving no
function. Again, it could have broken
up the potential for contiguous set of
removals. So we approached the
landowner and wondering if he'd give us
permission to just yank the dam out.
And he was very supportive of doing
that. And all that kind of came on the
top of the fact that the Maryland
Department of Natural Resources, their
fisheries department, have been doing
monitoring on the Patapsco, at the fish
ladders that were on all these dams and
had been able to document the fact that
the ladders that were here were
actually ineffective for passing some
of the target species like alewife,
blueback herring, and American eel. And
so, what better way to pass these fish
than removing the dam.
Faith: Matt NOAA played a part on this
as well. What is some of the background on their role?
Matt: Sure, I'm part of the National
Marine Fisheries Service part of NOAA
and we have an interest in marine fish
that Serena was just describing these
diadromous fish. They spend some part
of their lifecycle in fresh water and
some of their life cycle in the ocean.
And so they need to travel between the
two. And we have a fish passage program
as part of our restoration center that
provides funding and technical
assistance to try and get these
projects done. So that's basically our
role how we've been a funder and and
folks like myself, we give technical assistance.
We give funding for implementation as
well as, especially in this case, we
fund monitoring of project results –
for lots of reasons. Obviously, you
want to know the effectiveness of the
project for the fish passage. But these
projects have also other implications.
For example, in this case, we have a
large accretion of sand behind the dam
that we released through the removal.
We don't always release sediments
accreted behind the dam when we do
removals, but that's increasingly
becoming a – I don't know about a
preferred – but an appealing technique.
Because it can be a lot less costly if
the sediments are cleaned. But,
obviously, downstream interests, both
living, biotic, aquatic resources,
floodplain animals and whatnot and
humans, go through human life and
property have interests downstream. So
we have a strong interest in
understanding in detail, the effects of
that kind of sediment load and so, as
you'll hear, I'm sure, from these two
more about those efforts to learn more
details about those impacts. And
importantly, the recovery rates of the
downstream reach of those kinds of impacts.
Faith: That's great. We have a lot of
sediment. What's the story behind this
dam, especially sand—Allen your
background is in looking at physical
processes and how rivers change, what
do you expect to see as the sediment is released?
Allen: Well, what's important is that
rivers are in an equilibrium, with
sediment, slope and water, and when we
remove a dam we have the potential to
change any of those factors. Now
sediment moves as bedload and suspended sediment.
Faith: So like in the water and on the bed of the channel…?
Allen: Right, so we have sand behind
the dam to move along the bed or in
suspension. The release of that
sediment has the potential to actually
change the channel morphology. So we
need to understand how that
potentially could happen and how that
can affect habitat. So we're interested
in both understanding bedload transport
as a result of removal, as well as the
finer material in suspension that has
the ability to bury the habitat, or go
downstream and affect Chesapeake Bay.
Faith: So, as part of it, so we're
looking at effects both upstream of the
dam too and how much a sediment is
coming out and where it's all going.
And that takes some for that to happen,
right; it doesn't all go out in one big
pulse of release kind of thing. So
Graham, McCormick Taylor is doing some
of the work, what's kind of a scale of
what you have to do to be able to
monitor some of those changes?
Graham: Well, we've established a
series of 31 different cross sections,
extending from about a mile upstream of
the dam, all the way down, pretty close
to the mouth near the inner Harbor. So
it's going to include facies mapping,
where we're going to actually map the
river – the way the river looks so that
we can tell before and after the dam
removal, what the bed of the river
looks like. We're also going to be able
to quantify the amount of sediment that
is being deposited in these areas, and
the amount of sediment that's been
released from the dam.
Faith: You're kind of tracking it
through… and how long are you going to
have to do that for?
Graham: That's going to go on for five years.
Faith: Five years?
Graham: We're going to do a series of
six different surveys, twice a year,
and then following one larger storm
event. Hopefully a hurricane.
Faith: Great. Yes, a lot of different pieces.
[Music playing]