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.
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.