Hardened shorelines protect buildings, roads, and homes, but many developers say a more natural method should be used. (Photo by Lester Graham)
Along many Great Lakes cities, long concrete or stone seawalls protect property against
wind and wave erosion. It’s a hardening of the shoreline that some people say is
necessary to protect expensive real estate. But some scientists and environmentalists say
it’s part of one of the ‘Ten Threats to the Great Lakes. They’re worried those concrete
seawalls are not only hurting the environment… in the long run, they’re hurting the
economy. Lynette Kalsnes has this report:
Transcript
In our series ‘Ten Threats to the Great Lakes,’ we’ve been looking at how humans make
changes that affect the health of the lakes. Lester Graham is our guide through the series.
He says the next report shows how far we’ll go to try to manage nature:
Along many Great Lakes cities, long concrete or stone seawalls protect property against
wind and wave erosion. It’s a hardening of the shoreline that some people say is
necessary to protect expensive real estate. But some scientists and environmentalists say
it’s part of one of the ‘Ten Threats to the Great Lakes. They’re worried those concrete
seawalls are not only hurting the environment… in the long run, they’re hurting the
economy. Lynette Kalsnes has this report:
(waves lapping against concrete wall)
In the middle of a miles-long concrete shoreline, there’s a tiny beach. Steve Forman points
toward a small bluff at the base of a tree. The professor of earth and environmental sciences at
the University of Illinois at Chicago says the sand, grass and dunes help soften the impact of
waves and rain.
“This kind of relief is what you’d see in many natural coastlines, a coastline like this can
accommodate change better than one that’s been concreted up.”
Just feet away, the concrete picks back up, like a stark white runway that bisects the land and the
lake. Concrete revetments like these in Chicago are a familiar sight in urban areas across the
Great Lakes.
Roy Deda is with the U.S. Army Corps of Engineers. The Corps manages much of the
construction on public shorelines. Deda says hardening the shore is one way of protecting against
erosion.
“Where hardening of the shoreline is important and used, is where you have an existing
community in an urban area like Chicago. You have a lot of development in place already, and
basically you’re protecting what’s been built over a long history.”
Deda says it protects property. But scientist Steve Forman says using concrete walls comes at a
cost: the destruction of natural systems that are often helpful.
Forman says wetlands and stream valleys normally act like a sponge to absorb high lake levels.
They also release some of the water back when lake levels are low. Forman says concrete can’t
buffer those fluctuations.
“It makes the extremes potentially even more extreme in terms of lake level variations.”
So, when there’s a rainstorm, Forman says the water runs off the concrete quickly… instead of
being absorbed across sand or wetlands slowly.
He says the same thing is true for the water flowing into the lakes from rivers.
Discharge into rivers can go up by 50 times the amount it would if natural areas buffered the
rivers.
“Any time we change the landscape from its natural components, we also change the plumbing of
the Great Lakes. We change the way water is routed in and around and through the Great Lakes
as well.”
It’s not only rushing rivers and lake levels that cause problems.
When the shoreline is hardened… the wildlife and organisms that once lived there disappear.
Cameron Davis is with the Alliance for the Great Lakes. He says many rare species live in that
narrow ribbon where the land meets the water.
“When we harden the shorelines, we basically sterilize them in a lot of ways, because we’ve not
providing the kinds of habitat and cover that we need for many of them.”
And beyond the effect on wildlife… hardening the shoreline can also be a bad economic decision.
Steve Forman says permanent structures built near the shores are not as stable as they might seem
when lake levels are high and winter storms cause big waves that erode the land underneath them.
“When the lake levels go up, the erosion rates are just phenomenal…what you see are hanging
stairs everywhere, instead of stairs that take you down to the beach, they’re hanging over the lake,
basically.”
That’s why scientists and planners are taking action. The Alliance for the Great Lakes’ Cameron
Davis is calling on planners to balance protecting the shoreline … with preserving ecology.
“Frankly I don’t think shoreline planning across the region is that great. There really is no single
unifying policy we’re all using to guide what our shorelines ought to look like.”
He’s hoping that some cities will experiment with restoring natural areas along their shorelines…
He says we need to see if in the long run, nature can do a better job of protecting the shores.
For the GLRC, I’m Lynette Kalsnes.