Saving water in America (1)

A dam-building fervour in the south-western United States nearly killed its rivers, before a concerned public started a campaign to nurture them back to health. Zhang Kejia explores the lessons for China.

The Colorado River is one of the most dammed in the world. Over the last two hundred years, fortunes have been made harnessing its flow. But the Colorado’s role in supporting a unique and biodiverse ecosystem for long went unnoticed.

Recently, I was lucky enough to visit the area and see for myself its rivers, mountains, forests, grasslands and snowfields. But what made the greatest impression on me was the contrast between US and Chinese attitudes when it comes to dams and ecology; to development and conservation.

About 50 years ago, people in the United States realised that the country had made a huge blunder; too many dams were causing rivers to dry up, deltas to become deserts, and species to disappear, with many varieties of fish facing extinction. The idea of returning the rivers to nature took hold and, decades of hard work later, we are seeing the results: sluice gates opened according to the needs of fish; some dams demolished; nearby forests, grasslands and wetlands recovering; birds returning to their old haunts; and threatened alligator populations rising.

Unfortunately, the foolish errors made by the United States in the past are still happening in China.

The most important – and last – endangered fish reserve on the upper reaches of the Yangtze River is soon to be “moved” to allow the building of the Xiaonanhai Dam. Aquatic organisms unique to the river are, one after the other, being sacrificed, and this relocation of the reserve will prove a disaster for biodiversity.

Even more astonishing is a recent announcement by China’s Ministry of Environmental Protection. While construction of two dams on the Jinsha River, a western tributary of the Yangtze River, will cease, work is set to begin on a dam at Liyuan on the same river. This is close to Tiger Leaping Gorge, home to stunning rapids and the stretch of the Jinsha River least affected by humans. The Liyuan reservoir will partially submerge the Haba Snow Mountain nature reserve as well as Jade Dragon Snow Mountain and its celebrated scenery.

China’s rivers, lakes and wetlands are already in a sorry state. Despite the desperate pleas and unstinting efforts of scientists, conservation groups, the public and the media, the interest groups that thirst for profit from the rivers have not been stopped.

Robert Wigington is a freshwater conservation expert at The Nature Conservancy (TNC) and is based in its Colorado office, in the city of Boulder. He says his organisation aims to have one million kilometres of river under protection and flowing freely by 2020.

TNC has 170 river and freshwater experts and runs over 500 river recovery and protection projects worldwide. In the United States, it works with the US Army Corps of Engineers (USACE), which is known for building dams, on ecology protection projects around 60 dams of particular importance for biodiversity.

According to Wigington, the Colorado River flows through many different ecosystems during its course from the mountains to the river basin, and is of huge ecological value. It irrigates some 23,000 square kilometres of farmland and provides water for many cities, including Phoenix, Las Vegas, Denver and Salt Lake City. Analysis of its 45 different ecosystems – including comparative studies of soil constituents, fish, microorganisms and aquatic plants – has shown that, while the upper reaches of the river are well-protected, downstream there are problems.

On the Colorado River, USACE and TNC have removed just one dam, concentrating instead on mimicking natural river flows. This allows fish to breed naturally and ensures the dams can continue to generate electricity and provide water for irrigation.

The next stop on the tour is the Flaming Gorge Dam in Utah. Looking down from the 229-metre high structure, you can see five metres into the clear waters below and watch the huge brown and rainbow trout swimming around. The Green River downstream is said to offer some of the best trout fishing in all of the US. These are not farmed fish and the dam operators are not even allowed to catch them – local bylaws state that fishing must take place at least one kilometre downstream of the dam.

John Morgan, an official at the US Bureau of Land Management, tells me about his work to protect the river’s four endangered fish species – the bonytail, the Colorado pikeminnow, the humpback chub, and the razorback sucker. Images of these are two a penny in Colorado; found everywhere from newspapers and tourist brochures to restaurants, schools and even the family fridge. Their numbers are seen as a measure of how well the biodiversity of the Colorado River is recovering and they are a major part of the work of TNC’s Colorado office.

On the way to Flaming Gorge, we pass a 20-metre high dam on the Yampa River, which is now defunct. The structure reached the end of its working life years ago and is no longer needed to keep the river navigable, generate electricity or irrigate fields. But in response to TNC pleas, its operators have kept the water flowing to allow fish to pass through. Most importantly, the dam raises the water level downstream every spring in line with scientific advice, allowing fish – including those four endangered species – to reach their spawning grounds more easily.

The dam is said to have survived because the locals like to see it standing there; it has become a part of the landscape. Plus, it would cost US$2 million (13 million yuan) to dismantle. But, while it has hung on through the dams debate, some now say its days are numbered. One TNC project worker tells me it will be “demolished soon” – the costs of maintenance and ensuring it is safe are now as much as the costs of demolition.

The Flaming Gorge Dam was completed in 1964, bringing 50 years of regular flooding to an end. Photos in its exhibition hall record two major inundations that killed dozens and left many more homeless when riverside towns and homes were swept away.

There may have been no floods since the dam was built, but there are a lot less fish. By the 1970s, monitoring data found that the populations of the four endangered species mentioned above had fallen by 99% – and the remaining 1% was unsustainable.

According to fish experts, dams cause extinction by blocking routes to spawning grounds. They also create a steady, year-round flow of water, putting an end to the seasonal fluctuations that tell the fish when it is time to reproduce. And, as the waters at the base of a dam are very cold, the fish are forced to swim further to find warm waters in which to spawn.

After the last of these problems was identified in 1978, the way in which water is released at Flaming Gorge began to change, explains Morgan. “We realised we couldn’t just raise the sluice gate and let water out of the bottom of the dam any more, as that water is cold,” he says. “We needed to find a way to give the fish warmer water.”

Their solution was to install three extra gates in the dam, at different heights. During the spring floods, water is released from the top of the reservoir at about 18 degrees centigrade; the natural temperature of the river water and just what mating and spawning fish need.

A document put together by the US Bureau of Reclamation, TNC, and a number of conservation groups, says that water released by the dam in winter should be no colder than 6° Celsius and, in summer, no colder than 18° Celsius. Nor should the water released be more than 5° Celsius colder than the natural river temperature.

The fruits of this strategy are being seen – the populations of the four endangered species have clearly increased and other, less endangered species are also benefitting.

China also has a story about endangered fish – this time relating to three species – but it has a very different ending. When dams were being built on the upper reaches of the Yangtze River, fish experts and conservationists called for efforts to be made to save the Chinese sturgeon, Chinese high fin sucker fish and the Yangtze River dolphin, which are all unique to China. But one advocate for the dams summed up the response: “It’s just three fish! Are there not enough to eat in the fish farms?”

Zhang Kejia is a reporter for China Youth Daily

NEXT: Recognising the value of a nation’s rivers
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