Living shorelines require careful planning
By BRAD RICH
Coastal Review Online
Last of two parts
shorelines offer many benefits over the wooden and rock walls that are
customarily used to control erosion along estuarine shores. But
researchers say they have to be carefully planned and sited to make
sure that “living shoreline” projects aren’t little more a bunch of
rocks with a little grass thrown in.
Gittman knows that fish like a good living shoreline project. A
graduate student at the University of North Carolina’s Institute of
Marine Sciences in Morehead City, Gittman has been studying living
shorelines and her research indicates that they are “fish-friendly.”
June to October 2010, Gittman surveyed 25 salt marshes from Nags Head
in the north to Cape Fear in the south, to see if fish could get behind
the constructed sills and into the marsh.
she found was that fish, mostly small, were able to get into the grassy
areas of the marsh. There were even some larger predator fish, which
came in to feed. And research after Hurricane Irene did nothing to
dispel her initial assessments from two years ago, she said recently.
Currin is a marine scientist with the Center for Coastal Habitats and
Fisheries Research, a NOAA facility on Pivers Island in Beaufort. She
has also been researching living shorelines for years, focusing on the
structure and function of estuarine intertidal habitats, the marine
food chain, fish production and restoration of salt marsh habitats.
Gittman, she has assessed how natural shorelines fared during Irene and
was impressed. In some cases, she said, the storm resulted in a net
increase in sediments behind the sills.
understands that some developments, such as marinas, will always find
bulkheads necessary and she knows that it’s hard to combat the views of
many who like the aesthetics of bulkheads, with their straight lines
and neat, trimmed grass right up to the wall. But her work has
convinced her that living shorelines maintain ecosystems, fish habitat
and the nutrient cycle, all while offering significant and cost
effective erosion control.
Living Shoreline Problems
But living shorelines are not a panacea; there are still problems, major ones in the opinion of some.
Young, head of the Program for the Study of Developed Shorelines at
Western Carolina University; Orrin Pilkey, the famed geologist from
Duke University; and other collaborators surveyed living shoreline
projects along the Gulf and East coasts. A growing number, they
concluded in the resulting report, Rethinking Living Shorelines, “are
relying more on massive hard stabilization with less emphasis on
natural stabilization or the development of a significant habitat
component, as was the original intent of early ‘living shoreline’
‘living shoreline’ projects in the report vary widely in design, the
degree of stabilization, the amount of habitat creation and how well
they’re monitored. Some projects are used to protect private property,
and some are designed to reduce the erosion on the margins of existing
wetlands, it notes.
short, the term living shoreline is being used to describe everything
from well-constructed, vegetative stabilization projects to massive
rock revetments where a small planting of marsh grasses seems to be an
afterthought,” the authors add.
researchers worry that the massive rock structures used in some of
these ‘living shoreline’ projects will cause long-term environmental
degradation, provide a false sense of accomplishment and shift
the focus away from trying to maintain the most natural estuarine
is a need for advocates of ‘living shorelines’ to more precisely define
and regulate this term so it is not misused simply to allow more
unnecessary and damaging hard stabilization of estuarine shorelines,”
the paper concluded. “We urge broad reconsideration of the use of
large-scale hard stabilization for ‘living shorelines’ and a renewed
scientific effort to evaluate the cumulative impacts of all existing
structures (bulkheads and living shorelines) on natural and physical
processes and ecosystems.”
and Currin said one source of the problems cited by Young is that many
contractors simply don’t know much about living shorelines. They’re
more accustomed to building bulkheads or other types of hard structures
to control erosion, they said.
agree with him (Dr. Young),” Gittman said. “I’ve seen some good ones
and plenty of bad ones. It’s about 50-50. There are definitely some
challenges in terms of education. They’re (contractors) used to
building walls, so that’s often what they will suggest. Some will say
that sills are not tall enough. But many times all you need to do is
have a sill that’s tall enough to baffle the waves a bit” so the marsh
grass behind it can survive.
Davis, the director of the N.C. Division of Coastal Management, agreed
that increased educational efforts are needed in order for natural
shorelines to play a larger role in shoreline stabilization in North
isn’t the only factor, and permitting also isn’t the only factor
driving costs,” he said. “We need to figure out ways to help people
address the costs. Although living shorelines are perceived as
expensive compared to bulkheads, that doesn’t always have to be the
case. It depends on the project design.”
Cost On Par with Bulkheads
Currin insisted that living shorelines are not prohibitively expensive
compared to bulkheads, and she and Davis both pointed to Weighing Your
Options, a 50-page booklet put together for NOAA and the division. It
shows how to build living shorelines, generally; gives cost estimates
for bulkheads and a variety of living shorelines, including
breakwaters, riprap revetments, vegetation alone, marsh sills and
oyster reefs; and explores the benefits and drawbacks of all of them.
the booklet says, cost an average of $135 a foot and require a lot of
maintenance – backfill and repair of cracks and holes – with an average
lifespan of 30 years. By contrast, it estimates that a marsh sill uses,
averages about $130 a foot for stone work and site work.
Planting, including labor and the plants, averages about $22 a foot.
Again, maintenance is required.
key, Currin said, is working with someone who has expertise, both in
picking the right system for a landowner’s particular piece of
shoreline – location and the energy of the waves and wakes, as well as
tidal fluctuations, are key factors – and in actual construction. But
some of the labor – as evidenced by thousands of volunteers who work on
projects around the nation – does not need to be turned over to a
and other advocates of living shorelines point out, too, that a natural
system has an overriding public benefit: preservation of salt marshes,
which are among the most productive habitats in the world.
nature, marshes retreat landward as they are buffeted by tides, waves,
wakes and rising sea levels. But a bulkhead prevents that retreat, and
a marsh so blocked will eventually disappear.
agreed there are problems with some projects, but said that given the
potential for living shorelines to positively impact both water quality
– filtering pollutants – and marine habitat, as well as shoreline
erosion, the state needs to continue to try to make it easier to build
living shorelines and harder to build bulkheads.
going to take time, because it’s a different philosophy than most
people have had in the past,” she said. “But I think they (the state
officials) are moving in the right direction.”
More Training Needed
said the state can also help simply by encouraging property owners to
explore the alternatives to bulkheads and said his office is doing that
much more often than in the past.
done training for our staff, and we’re developing training courses (for
contractors and others),” he said. “Our field staff is encouraged to
ask people who want to stabilize the shore, ‘Have you explored this.’
Sometimes, though, that happens too late in the process.”
The state, he said, is continuing to learn more about shorelines
stabilization and about exactly what techniques are used and how those
techniques fare in storms.
looking at that, and we also just finished our first digital map of the
entire North Carolina shoreline,” he said. “For the first time, we have
good clear images of all of the types of structures. This will allow us
to evaluate better the extent and the effectiveness of those
Young said he doesn’t favor the “general” permit approach for living
shorelines, because it shouldn’t be too easy to do anything that alters
the natural shoreline. He’s not, he said, ever going to say he wants to
see “rocks put in the water.”
But he doesn’t want anyone to get the opinion, from his paper, that he thinks living shorelines are worse than bulkheads.
real problem is the rate at which we are armoring our estuarine
shoreline, locking it off, causing incredible damage, particularly if
sea level continues to rise,” he said. “What we were saying is that we
saw many ‘living shoreline’ projects that were mostly engineered
structures with a little bit of marsh grass, lipstick on a pig.
Coastal Federation, I would say, does a good job with their projects,
certainly a better job than most. Their projects generally have a large
degree of ‘natural’ material,” Young said. “But if you look at the
project that’s on the cover of our paper – at the North Carolina Center
for the Advancement of Teaching on Ocracoke – well, let’s just say that
I’d rather not see them involved in any more projects like that one in
the future. That shouldn’t be the model.”
special circumstances drove the design of that project, noted Erin
Fleckenstein, a federation coastal scientist. A few bags of oyster
shells and some marsh grass seedlings wouldn’t have worked there, she
said, because of the battering the site takes.
waves – for Pamlico Sound -- generated over a long stretch of open
water are routine, Fleckenstein explained. So are large wakes kicked up
by state ferries and other large vessels entering the adjacent entrance
to Ocracoke’s harbor.
center is in a remodeled former Coast Guard station. The state wanted a
finished product that would protect its $5 million investment,
“It’s over-built by Coastal Federation standards,” she said. “But given those other parameters, it’s totally appropriate.”
states, including Mississippi, are moving toward making it too easy,
Young said, to permit living shoreline projects “before we have
really agreed on what a ‘living shoreline’ is. If we’re going to go in
that direction, than we had better have a damn good idea of what is
really a ‘living shoreline’ and what is really an engineered shoreline
stabilization project with a little bit of a natural component,” he
don’t think NOAA has drawn that line yet, and I don’t think the Coastal
Federation has, either. We need to have that conversation, and I think
any organization that is trying to ‘sell’ living shorelines should be
happy to have that conversation.”
also said he realizes it’s impractical to insist that shoreline
stabilization never take place, because there are some developments
along high-energy shorelines that are going to be protected, whether
anyone likes it or not. The goal should be to strictly limit those and
to use real natural shoreline projects – as “gentle an approach as
possible,” Young said - whenever something must be done and natural
shorelines will work. And, of course, to encourage letting nature have
its way – shoreline retreat – as much as possible.
problem “in a nutshell,” Young concluded, is that it’s easy to
quantify, in dollars the enormous losses when erosion destroys
developed shorelines. There’s tremendous pressure not to let that
It’s not so easy to quantify the damage caused by the loss of estuaries
due to shoreline projects that increase pollution and destroy of
critical marsh habitat.
story is provided courtesy of Coastal Review Online, the coastal news
and features service of the N.C. Coastal Federation. You can read other
stories about the N.C. coast at www.nccoast.org.)