Rivers: Dams, Canals and Channeling: Page 3 Endangered Species Handbook

Aquatic Ecosystems

Rivers: Dams, Canals and Channeling: Page 3

The Aral Sea, 300 miles to the east of Siberia's Lake Baikal, is ancient in origin. This was once the fourth-largest lake in the world, covering 25,000 square miles (Kinzer 1997). Two giant dams were constructed in the 1960s on its two feeder tributaries, the Amu Darya and Syr Darya. The diverted water was sent to the south to produce cotton (Filipov 1997). This crop requires great amounts of water and is unsuitable for the arid steppe region. The loss of its feeder rivers caused the Aral to shrink over the next 30 years from 25,675 square miles to 14,090 square miles, and its shores receded up to 50 miles (Stewart 1992). By 1997, it covered only 12,000 square miles, and it continues to shrink (Kinzer 1997). This once rich lake in the midst of the dry plains of Central Asia is expected to completely dry up by 2010 (Filipov 1997). As it dried up, the sediment from the Aral Sea's bed, which contained toxic chemicals, blew away, coating everything within hundreds of miles with 150 million tons of contaminated dust (Filipov 1997).

The wealth of diversity that once teemed in this desert sea has been lost. The destruction of this beautiful lake and its wildlife is without parallel anywhere in the world in recent history, an environmental catastrophe. The water that remains has become increasingly saline and polluted by unregulated industries (Filipov 1997). The collapse of the fishing industry has caused great financial hardship to the people who had lived along the shores of the Aral for centuries. In the 1950s, the Aral produced 40 to 50 tons yearly of sturgeon, pike and roach, among other species of fish; all of its 24 endemic fish are now extinct (Stewart 1992). The mayor of the town of Muynak, located at the southern end of the lake, recalled, "Our fishing boats used to bring in 30,000 tons of fish each year." The town's population dropped from 45,000 in 1967 to 28,000 in the late 1990s (Kinzer 1997).

Of the Aral Sea region's 173 animal species, only 38 survived until the early 1990s (Stewart 1992). Almost all birds disappeared, along with the last of the fish, and only brackish pools remain along the shoreline (Filipov 1997). In March 1991, the Aral Sea was officially declared an ecological disaster area, and the Soviet government appealed to the United Nations Environmental Programme for help; an inter-republic commission was set up to reduce pollution, but with the dissolution of the USSR., the project was abandoned. In the years since the Soviet Union dissolved, destruction has continued unabated (Filipov 1997).

The five newly established Central Asian nations of the region, Kazakhstan, Uzbekistan, Krygyzstan, Tajikistan and Turkmenistan, are now competing for control of the water from its two feeder rivers to maintain their irrigation-fed agriculture (Filipov 1997). Although the leadership of these countries agree urgent action is required to save the Aral Sea, they are not ready to take drastic measures to conserve water (Kinzer 1997). Ironically, much of the diverted water is lost to evaporation and seepage because the irrigation canals were neither covered nor lined (Kinzer 1997). What water is left after heavy application of pesticides and other chemicals sprayed on cotton and rice fields becomes poisoned and trickles into the Aral, further contaminating it (Kinzer 1997). Cancers and other illnesses have struck the local people in Muynak (Kinzer 1997). An environmental organization, Aral-S-O-S, is attempting to reach agreements among the countries, but admits the countries' philosophy of considering water their national property may make the goal unattainable (Kinzer 1997). These nations continued discussions in 2000 without taking any action to prevent the impending loss of the Aral Sea.

In the majority of cases, dams are constructed with little or no knowledge of the ecosystems they are ruining. Likewise, the governments that authorize the dams rarely consider environmentally sound alternatives. In the 1940s, the Volga and Kama Rivers, 300 kilometers north of Moscow, were dammed to form an enormous reservoir that flooded 455,000 hectares (1,124,305 acres) of arable meadowland to produce a relatively small amount of electricity (Lanz 1995). Dams on the Volga impeded the natural migration of sturgeon from the Caspian Sea for their spawning, resulting in a catastrophic decline in the world's most valuable fish. Beluga caviar from the beluga sturgeon (Huso huso), an endangered species, is the most valuable fisheries product in the world, made more valuable by its continued decline in the Caspian. All the Caspian's species of sturgeon are endangered, as are species of the Amu-Dar and Syr-Dar Rivers feeding the Aral Sea.

The Three Gorges, a Yangtze River Dam project in China that will be completed in the next five years, will be the world's largest hydro-electric project. This dam, expected to cost up to $120 billion, will be 607 feet high, span over a mile and flood 400 miles of this major river, including 30 million acres of cultivated land (Carpenter 2001). The portion of the Yangtze River to be dammed is one of the most picturesque landscapes on Earth, its swift waters flowing through steep gorges and mountains enshrouded in mist. It has been painted by Chinese artists for centuries. The three gorges that will end up under water, the Qutang, Wu and Xiling Gorges, have tributaries and feeder streams that will also be adversely affected. One of these, north of the town of Wushan, the Daning River, is home to many ancient species of trees, such as the Dawn redwood (Metasequoia glyptostroboides), the dove tree (Davidia involucrata) and various ginkgoes (Hoh 1996). Forty-seven species of rare or endangered plants listed by the Chinese Academy of Science will be inundated when the dam waters rise; among these are many endemic medicinal plants (Hoh 1996). Funds are lacking to treat the 265 billion gallons a year of raw sewage and industrial waste that will flow into the impounded waters from the Three Gorges Dam (Tyler 1996). The project's managers admit there are no immediate solutions to the sewage and pollution problem, or to the impact of huge volumes of sediment that could clog the entire flow of the river (Tyler 1996).

The Yangtze River dolphin (Lipotes vexillifer) inhabits this part of the river and faces imminent extinction. Restricted to the Yangtze and portions of the Quiantang River, it has disappeared from much of its original range (Nowak 1999). This dolphin evolved in swift, muddy waters, preferring to live near large eddies. The sonar in its bulbous head is able to locate fish without vision. While this species is actually almost blind, these dolphins have tremendous physical strength to negotiate strong currents. Boat travelers in the river 50 years ago saw hundreds of these dolphins leaping and swimming throughout its length, along with birds and other wildlife. Today, almost no wildlife can be seen. This species was endangered by other dams, collision with boats and ships, dynamiting for channel maintenance, pollution, accidental drowning in fishing nets and loss of food to over-fishing by humans, even prior to the Three Gorges dam construction (Nowak 1999). A large male found dead in January 1996 was examined by scientists; they determined he had died from an electric shock device used to kill fish in the Yangtze River (CNN 1996).

The lakes along the Yangtze once sheltered hundreds of dolphins, but sedimentation from agricultural runoff covered the lake bottom, and sewage polluted the water. It has disappeared from almost all its former strongholds. Surveys in 1986 found 300 animals, but in 1993, 200 or less were estimated to remain, and more recently only 9 individuals could be found (Nowak 1999). This species, adapted for millions of years to life in these rivers is now considered the most endangered of all cetaceans (Nowak 1999). The upper Yangtze will soon be awash in sewage and other pollution from the Three Gorges Dam, which will also block its movements, a habitat where these last dolphins are unlikely to survive. The sole native dolphin in captivity, Chichi, a male, has lived in a small concrete tank at the Institute of Hydrobiology in Wuhan since 1980 when fishermen snagged him on their hooks; he still has scars from these wounds. Pneumonia killed one young female placed with him, and several other females put in his tank in the hopes of captive breeding have died as well, according to a 1999 PBS documentary, "Great Wall Across the Yangtze."

Ocean Park Conservation Foundation in Hong Kong, in cooperation with the IUCN Cetacean Specialist Group and the Institute of Hydrobiology in Wuhan, China, have cooperated in a project to capture as many of the remaining animals as possible before the dam fills and move them to the Shishou Seminatural Reserve (Leatherwood and Genthe 1995). The reserve, a natural oxbow in the Yangtze, also harbors ten finless porpoises (Neophocaena phocaenoides) – a species that has lived in the river with the dolphins for thousands of years. Finless porpoises are also native to coastal waters west to Saudi Arabia, but their status is not well known. This solution is unlikely to protect more than a few members of the species, and it will almost certainly fade into extinction in the near future. Another species unlikely to survive the effects of this dam is the endemic, migratory Yangtze sturgeon (Acipenser dabryanus).

The dam will also affect the Yancheng Marshes, covering some 938 square miles on the north-central coast. Extending for 186 miles, they form a floodplain for the Yangtze River (Simon 1995). Over half a million water birds and shore birds winter here, including the highly endangered red-crowned crane (Grus japonensis), whose population in this wetland increased from 200 in 1981 to over 600 in 1987 (Simon 1995). The tidal flats of the Yangcheng are being reclaimed for agriculture, presenting another threat to this species, whose world population totals only about 2,200 birds (BI 2000). Another rare bird, Saunder's gull (Larus saundersi), has a world population of only 7,000 birds in decline (BI 2000), breeds in the Yancheng (Simon 1995). This marsh is of great importance to the 226 birds recorded here, since the vast majority of wetlands in China have been drained, polluted or are heavily hunted (Collar et al. 1994). For Pere David's deer (Elaphurus davidianus), the Yangcheng Marshes are a new home, one of several reintroduction sites for this species that became extinct in the wild and was rescued by captive breeding in England (Simon 1995).

Another water project, said to begin in two years, will divert water from just west of the Yangtze north to Tianjin, a city southeast of Beijing that is suffering water shortages (Eckholm 2000). Should this be carried out, the combined effect of this diversion and the Three Gorges Dam will decrease the flow of the Yangtze River so greatly that these marshes may dry up. Water from the Yangtze River west of the Three Gorges Dam will also be diverted north to the Yellow River, which has been overused and sometimes runs dry, and to mountain zones in the northwest and south (Eckholm 2000). Canals and reservoirs will be dug to carry this water in projects that will cost more than $12 billion (Eckholm 2000). The effects of these diversions on the remaining wildlife of this river will be devastating.