Removing a Dam to Restore a River - Test 3
B2 First · Gapped Text · Cambridge English First 3, Cambridge University Press
You are going to read an article about a dam removal project. Six sentences have been removed from the article. Choose from the sentences A-G the one which fits each gap (1–6). There is one extra sentence which you do not need to use.
Removing a dam to restore a river
Journalist Richard Lovett is taken to see how a river has come to life again after a dam has been removed.
The water there had become so shallow that it was possible for people to wade all the way across.
'People pay attention to the big fish,' Coffin says. 'Yes, they're an important part of the system, but they're not the only things.'
One result of these projects has been an unanticipated research opportunity to study how to minimize the damage caused by releasing huge floods of water and decades of sediment.
However, the reservoir lost its water and much of its mud, sand and gravel in three hours.
Coffin leads me through patches of alder trees that were planted after the dam was removed, then crosses a rocky beach by the river.
In the process of doing this, the workers rediscovered the river's original channel along the reservoir bottom.
Built back in 1935, the structure provided power and irrigation for a nearby tree nursery that shut down in 1997.
Just outside the small town of Stabler in Washington, hydrologist Bengt Coffin surveys a mountain river he helped to revive. Today, the clear waters of Trout Creek run fast between banks covered in young alder trees. But just five years ago, an eight-metre-high concrete wall blocked the river at the site. This dam and the reservoir behind it had changed the river completely and made it difficult for fish such as the endangered steelhead trout to return to where they were born in order to breed. For one thing, the reservoir was full of sediment – mud, sand and gravel. It was Coffin who led the US Forest Service effort to remove the dam. This is all part of a growing trend in the United States. An increasing number of dams are being removed, for financial and environmental reasons.
Some schemes take a slow path, restoring river flow over months or years. Others use explosives and other engineering techniques to drain reservoirs within hours. At Trout Creek, Coffin and his colleagues decided to take the cautious route when removing the ageing Hemlock Dam.
The dam had been designed to include what is called a fish ladder, which allows fish and other animals to bypass the dam and swim upstream, but it was poorly built by modern standards and the number of fish using it had steadily declined. A bigger concern was the reservoir, which had been steadily filling in with sediment.
Coffin holds a hand above his knee to make the point. In the midsummer sun, temperatures in the water could reach 26°C; 'Too warm for steelhead,' he says. Coffin and others worried that flooding the river with all that sediment would harm the steelhead further downstream. The solution was to divert the river into a big pipe and then hire a fleet of dumper trucks to carry away all the sediment.
They then reinforced its banks with logs to stop them from eroding. All those efforts seem to have worked. Just seven hours after water was allowed to flow back, Coffin's team could clearly see the first steelhead venturing into the stream's channels upstream from the old dam site. But there is another sign of success which Coffin is keen to reveal.
The rounded stones on it range from the size of potatoes to loaves of bread, and make walking difficult. But Coffin is thrilled to see them because they are newly arrived, having just been washed in by the current. The stones in the river provide nesting spots for the steelhead and a habitat for the insects that they eat.
To illustrate this, he turns over a couple of rocks and points out six types of insect clinging to the underside, including caddisfly larvae and a stonefly. 'The year after the dam was removed, these wouldn't have been here,' he adds with satisfaction.
Just outside the small town of Stabler in Washington, hydrologist Bengt Coffin surveys a mountain river he helped to revive. Today, the clear waters of Trout Creek run fast between banks covered in young alder trees. But just five years ago, an eight-metre-high concrete wall blocked the river at the site. This dam and the reservoir behind it had changed the river completely and made it difficult for fish such as the endangered steelhead trout to return to where they were born in order to breed. For one thing, the reservoir was full of sediment – mud, sand and gravel. It was Coffin who led the US Forest Service effort to remove the dam. This is all part of a growing trend in the United States. An increasing number of dams are being removed, for financial and environmental reasons. ___ Some schemes take a slow path, restoring river flow over months or years. Others use explosives and other engineering techniques to drain reservoirs within hours. At Trout Creek, Coffin and his colleagues decided to take the cautious route when removing the ageing Hemlock Dam. ___ The dam had been designed to include what is called a fish ladder, which allows fish and other animals to bypass the dam and swim upstream, but it was poorly built by modern standards and the number of fish using it had steadily declined. A bigger concern was the reservoir, which had been steadily filling in with sediment. ___ Coffin holds a hand above his knee to make the point. In the midsummer sun, temperatures in the water could reach 26°C; 'Too warm for steelhead,' he says. Coffin and others worried that flooding the river with all that sediment would harm the steelhead further downstream. The solution was to divert the river into a big pipe and then hire a fleet of dumper trucks to carry away all the sediment. ___ They then reinforced its banks with logs to stop them from eroding. All those efforts seem to have worked. Just seven hours after water was allowed to flow back, Coffin's team could clearly see the first steelhead venturing into the stream's channels upstream from the old dam site. But there is another sign of success which Coffin is keen to reveal. ___ The rounded stones on it range from the size of potatoes to loaves of bread, and make walking difficult. But Coffin is thrilled to see them because they are newly arrived, having just been washed in by the current. The stones in the river provide nesting spots for the steelhead and a habitat for the insects that they eat. ___ To illustrate this, he turns over a couple of rocks and points out six types of insect clinging to the underside, including caddisfly larvae and a stonefly. 'The year after the dam was removed, these wouldn't have been here,' he adds with satisfaction.
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