Freshwater failures: the crises on five continents.

• Author: Abramovitz, Janet N.

Societies have repeatedly misunderstood that their freshwater assets are not simple commodities to be tapped, channeled, or dammed at will, but complex living systems. As a result of that misunderstanding, many of these systems are in deep trouble.

In 1880, a decade before the territory of Washington became a part of the United States, 19,500 tons of salmon and steelhead trout were harvested from the region's most important river, the Columbia. One hundred years later, the harvest was just 50 tons. Fourteen million salmon a year once returned to this watershed to spawn in their ancestral streams; in 1992 only 1.1 million returned, and most of those were born in a hatchery. In Idaho, the coho salmon, one of the region's five salmon species, went extinct in 1986. In 1994, only 400 fall chinook salmon and just one sockeye salmon, nicknamed "Lonesome Larry" by Idaho's governor, completed the journey from the Pacific to Idaho's Redfish Lake.

To someone who does not live in the Pacific Northwest, this brief history might seem to be one of those disturbing but anomalous environmental disaster reports one occasionally hears about from some far-away and uniquely troubled place - the story of a nuclear accident in Chernobyl, an oil spill in Alaska's Prince William Sound, the burning of tropical rainforests, the slaughter of rhinos. But in fact, what has happened to the Columbia River is happening to freshwater bodies all over the planet - from the Mississippi to the Mekong, from Lake Erie to Lake Baikal, and from thousands of nameless streams and creeks across North America to their nameless counterparts on every other continent. The details vary, and the victims of the tragedy may not be as well known as the Pacific salmon, but the causes - and consequences for human economies, as well as for the earth's ecological stability - are much the same.

What freshwater environments share, worldwide, is a particular vulnerability to which most humans are largely - perhaps dangerously - oblivious. As biological assets, freshwater systems are both disproportionately rich and disproportionately imperiled. On the one hand, 12 percent of all animal species - including 41 percent of all recognized fish species - live in the 1 percent of the earth's surface that is freshwater. On the other hand, at least one-fifth of all freshwater fish have become extinct, threatened, or endangered in recent years, and entire freshwater faunas have disappeared. The rate at which species are being lost far exceeds any natural extinction rate. Today, we are running what Smithsonian Institution biologist Jonathan Coddington refers to as a "biodiversity deficit" - we are destroying species (and ecosystems) faster than nature can create new ones to replace them. Such a course is no more sustainable over the long term than is a growing financial deficit.

Several case histories illustrate both the theme and its variations. And while the salmon case is not unique, what happened on the Columbia is instructive - and could serve as a valuable forewarning for the custodians of other freshwater systems.

THE COLUMBIA: LOSING THE SALMON

Because of their unusual life history, salmon are good indicators of the health of their region's rivers and forests. They are among the 1 percent of the world's fish species that are "anadromous" - living in both fresh and salt water. Salmon hatch in streams and rivers, then make their way out to the ocean, all the while undergoing enormous physiological changes. After several years, they return to their ancestral streams to mate, and often die. Under the best conditions, the odds are just one in 5,000 to 10,000 that a salmon egg will be fertilized and survive to a reproducing adult. And because these fish pass through a wide range of habitats and conditions, over distances as long as thousands of kilometers, they are vulnerable to the full range of forces that nature and humankind inflict.

Today, the salmon's biggest obstacles on the Columbia are dams. Dams alter the temperature and flow regimes of rivers; they are barriers to migrating organisms such as fish, and to the natural movement of sediments, nutrients, and water - all of which feed the surrounding habitat and ultimately the sea. In the past, a young salmon's journey to the ocean took two weeks; now it takes two months. Of all the salmon killed by human activity, habitat modifications - principally dams and reservoirs - kill an estimated 99 percent. A large proportion of the survivors must make an extremely unnatural detour: they are hauled around the dams in trucks and barges. Most of the Columbia River basin's dams were built during the heyday of hydroelectric development 20 to 50 years ago. Today, only 71 of the river's 1,996 kilometers run free, without the hindrance of dam or reservoir.

There are indirect obstacles to the salmon's journey as well. The Pacific Northwest has lost 80 percent of its once extensive primary forests to logging. In Oregon, even undammed streams have had their salmon populations cut by more than half, in large measure because of sedimentation from logging. Across the border, in Canada, the effects of logging and mining on undammed major rivers, such as the Fraser and the Skeena, have cut salmon populations to less than 20 percent of previously recorded levels. Grazing, irrigation, agricultural runoff, and wetland conversion have all contributed to the extensive degradation of the freshwater habitats of the Pacific Northwest.

The plight of the Pacific salmon is far from unique. Data from the Nature Conservancy reveal that in North America, the continent that has been most thoroughly studied, 67 percent of mussels, 64 percent of crayfish, 36 percent of fish, and 35 percent of amphibians are either in jeopardy or - in some cases - already extinct [ILLUSTRATION FOR FIGURE 1 OMITTED]. These high levels of extinction and endangerment are not artifacts of earlier perturbations - they are recent and increasing. Ten fish species went extinct in the last decade alone.

These losses do not happen simply because the fish of an affected species become fewer and fewer until they disappear. Much of the damage is being done below the species level, by the loss of particular "stocks." Many species, including salmon, are comprised of distinct populations that have evolved unique adaptations to their local environment. These fitness-enhancing characteristics may govern time and place of spawning, migration routes, and so forth. Fisheries biologists see these genetically different stocks as the building blocks of conservation and rehabilitation. According to a recent assessment of anadromous fish in the Pacific Northwest by the American Fisheries Society (AFS), 214 native, naturally spawning stocks are in serious trouble. Yet, only two of these have been given official protection under the U.S. Endangered Species Act.

Although most losses in the continent's freshwater fauna can be attributed to a variety of factors acting together, physical habitat alteration is implicated in 93 percent of the declines, according to an AFS study. This is hardly surprising, since in the United States, only 2 percent of the country's 5.1 million kilometers of rivers and streams remain free-flowing and undeveloped. Over 85 percent of U.S. inland waters are artificially controlled and over half the country's original wetlands (excluding those in Alaska) have been drained. So much water is diverted from rivers that many (such as the Colorado) dry up before reaching the sea (see "Running Dry," by Sandra Postel, in the May/June World Watch).

The second most common factor in the losses...