And now to our
"NewsHour" Shares.

Seawalls help to protect
developed shorelines,
but they can also
destroy crucial habitat.

One project in Washington
state aims to fix that.

Ken Christensen of
KCTS' EarthFix explains.

KEN CHRISTENSEN: The Seattle
waterfront is changing
right beneath your feet.

JEFF CORDELL, University of
Washington: When you walk along
Seattle's sidewalk, you will

be walking on glass panels.

KEN CHRISTENSEN: But look
deeper, and you will see that
the changes aren't for tourists.

They're for natives.

JEFF CORDELL: Their
function is to provide
light to help thousands
and thousands of little

baby salmon.

KEN CHRISTENSEN: It's
one feature of Seattle's
new seawall, a $400
million infrastructure

project that's doubling as a
really big science experiment,
the biggest of Jeff Cordell's

career.

JEFF CORDELL: Nothing has
ever been tried on this scale.

You're walking on foot after
foot after foot of new habitat.

KEN CHRISTENSEN: Cordell wants
to see if coastal cities can
better coexist with fish.

For 80 years, Seattle's seawall
was like most, a flat, concrete
slab that held back the sea,

but destroyed shallow
water habitat that
many species thrive on.

Every spring, young salmon
would migrate from Seattle's
Duwamish River to the ocean, and

they're hard-wired to stay
close to shore, which means
they run right into this.

In the inky darkness
under the pier, life can
get confusing for a fish.

JEFF CORDELL: There's
a good example of a
shadow line from a pier.

And they don't want to
cross the shadow line, so
they just mill about here.

KEN CHRISTENSEN: The new
seawall is supposed to make life
easier, not only by providing

a naturally lit corridor for
fish to pass through on their
way to the ocean, but also

by featuring overhangs and
rocky surfaces along the way
for fish food to grow on.

JEFF CORDELL: Look at
the brown scum here.

We love to see that,
because that's where
the little crustaceans
grow that the juvenile

salmon feed on.

You can't count out brown scum.

KEN CHRISTENSEN: Most seawalls
are still get built like
Seattle's was back in the 1930s.

And construction is
expected to increase.

JEFF CORDELL: There's going to
be much more need for coastal
infrastructure and a lot

more thinking about how we can
best create habitat for the
organisms that we're removing

it from.

KEN CHRISTENSEN: Once
the seawall is complete,
Cordell plans to begin
a decade-long monitoring

project to figure out if it
does what it's supposed to.

JEFF CORDELL: Even that
brown stuff needs a good
amount of sunlight to grow.

KEN CHRISTENSEN: If the
experiment succeeds,
the Seattle waterfront's
biggest change could

be the change it inspires in
seawalls around the world.

For the "PBS NewsHour,"
I'm Ken Christensen in
Seattle, Washington.