| Dear
EarthTalk: Would removing dams in the Pacific
Northwest allow the wild salmon that used to thrive there
return to their former abundance? -- Jake Garmey, Boston,
MA
Before white settlement in the Pacific Northwest (pre-1850),
each year some 10 million Pacific salmon--a so-called “silver
tide”--swam up the Columbia and Snake Rivers to spawn
at the streams and tributaries of their births. Native Americans
feasted and derived much of their cultural awareness from
the presence and cycles of these fish. Today as few as 10,000
salmon return home to the Snake River each season.
Over fishing and pollution--as well as the crossbreeding of
native fish with weaker hatchery-born fish--have since taken
their toll on wild salmon populations, but most analysts point
to the construction of eight large hydropower dams throughout
the Columbia/Snake system during the middle of the 20th century
as the key factor. According to noted Pacific Northwest naturalist
and writer William Dietrich, 106 salmon stocks have gone extinct
from Northern California to the Canadian border since the
dams were built.
According to Save Our Wild Salmon, a coalition of environmental
groups and commercial and sport fishing associations, dams
alone are responsible for the loss of 92 percent of salmon
headed out to sea and of up to 25 percent on their way back
upstream. “Fish are gone entirely from almost 40 percent
of their historic rivers,” says Dietrich, who adds that
most of the remaining fish are at risk, too, qualifying for
full protection under the Endangered Species Act. Quite simply,
the fish just cannot swim past the dams.
The idea of removing dams to restore salmon runs is not new.
Environmentalists rejoiced in 1999 when Maine removed the
162-year-old Edwards Dam on the Kennebec River to allow passage
for decimated stocks of Atlantic salmon. That dam was an obvious
choice for removal, as it provided only 1/10th of one percent
of Maine’s power needs, yet strained and drained 20
percent of the state’s watershed lands. In all, more
than 145 dams have been removed across the U.S. since the
Edwards Dam came down in 1999.
Environmentalists and biologists alike are calling for the
removal of dams along the Columbia and Snake Rivers, but doubt
that the National Oceanic and Atmospheric Administration (NOAA),
the agency responsible for developing a salmon plan, will
actively promote the idea. Dams in the Pacific Northwest produce
nearly seven percent of the nation’s electricity without
generating greenhouse gases, and the Bush administration is
eager to promote hydropower as one way to reduce our reliance
on foreign oil.
Meanwhile, the federal government is working to complete removal
of the Elwha Dam on Washington State’s Olympic Peninsula
by 2008. Built a century ago to generate power, the Elwha
Dam shut off 70 miles of habitat for the more than 500,000
fish that had spawned there each year. Today, just 5,000 wild
Pacific salmon swim up the Elwha River and school at the base
of the dam each year, looking for a way upstream that no longer
exists. The success or failure of the Elwha Dam removal will
certainly impact the debate about the prospects for removing
other hydropower dams in the Pacific Northwest and elsewhere.
CONTACTS: Save Our Wild Salmon, www.wildsalmon.org;
NOAA Fisheries Service, www.nmfs.noaa.gov;
Elwha Restoration Project, www.nps.gov/olym/elwha/.
PHOTO
COURTESY OF GETTY IMAGES
Salmon
are gone entirely from almost 40 percent of their historic
rivers. Hydropower dams are largely to blame.
Dear EarthTalk:
Is it true that nothing really “biodegrades”
in a landfill?
-- Laura, via e-mail
Organic substances “biodegrade” when they are
broken down by other living organisms (such as enzymes and
microbes) into their constituent parts, and in turn recycled
by nature as the building blocks for new life. The process
can occur aerobically (with the aid of oxygen) or anaerobically
(without oxygen). Substances break down much faster under
aerobic conditions, as oxygen helps break the molecules apart.
Most landfills are fundamentally anaerobic because they are
compacted so tightly and thus do not let much air in. As such,
any biodegradation that does take place does so very slowly.
“Typically in landfills, there’s not much dirt,
very little oxygen, and few if any microorganisms,”
says green consumer advocate and author Debra Lynn Dadd. She
cites a landfill study conducted by University of Arizona
researchers that uncovered still-recognizable 25-year-old
hot dogs, corncobs and grapes in landfills, as well as 50-year-old
newspapers that were still readable.
Biodegradable items also may not break down in landfills if
the industrial processing they went through prior to their
useful days converted them into forms unrecognizable by the
microbes and enzymes that facilitate biodegradation. A typical
example is petroleum, which biodegrades easily and quickly
in its original form, crude oil. But when petroleum is processed
into plastic, it is no longer biodegradable, and as such can
clog up landfills indefinitely.
Some manufacturers make claims that their products are photodegradable,
which means that they will biodegrade when exposed to sunlight.
A popular example is the plastic “polybag” in
which many magazines now arrive protected in the mail. But
the likelihood that such items will be exposed to sunlight
while buried dozens of feet deep in a landfill is little to
none. And if they do biodegrade at all, it is only likely
to be into smaller pieces of plastic.
Some landfills are now being designed to promote biodegradation
through the injection of water, oxygen, and even microbes.
But these kinds of facilities are costly to create and as
a result have not caught on. Another recent development involves
landfills that have separate sections for compostable materials,
such as food scraps and yard waste. Some analysts believe
that as much as 65 percent of the waste currently sent to
landfills in North America consists of such “biomass”
that biodegrades rapidly and could generate a new income stream
for landfills, marketable soil.
But getting people to sort their trash accordingly is another
matter entirely. Indeed, paying heed to the importance of
the environment’s “Three Rs” (Reduce, Reuse,
Recycle!) is likely the best approach to solving the problems
caused by our ever-growing piles of trash. With landfills
around the world reaching capacity, technological fixes are
not likely to make our waste disposal problems go away.
CONTACTS: U.S. Environmental Protection Agency
(EPA) Reduce-Reuse-Recycle page; www.epa.gov/epaoswer/non-hw/muncpl/reduce.htm.
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