This crisis begins, in classic chaos-theory fashion, with a trivial event along the 100-mile railroad track that moves most coal out of the Powder River Basin.

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Other coal companies have drifted out West to the Powder River Basin, where the coal lies right at your feet.

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The Permian Basin needs more CO2 to coax out stubborn oil.

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And there are mounds of gravel, and holes in the sides of the basin where gravel has been taken out, and high up in the steep sides there are little holes that are the little front doors of the little sand-martins' little houses.

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Those tours were on a 1.5-mile section in a 2, 000-acre park called the Sepulveda Basin Recreation Area, and the permits sold out in a matter of hours, denying large numbers of river lovers a legal chance to ply the waters.

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"You can work out the budget, and there is a phenomenal amount of nitrogen accumulating somewhere in the basin, " said Professor Tim Burt, also of Durham University.

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According to Dr McMahon, a big part of the problem is that both species can survive out of the water for several days, so transporting a boat overland from one river basin to another, a common practice in North America, will not necessarily kill them.

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"You need to think that you're going out to seek real solitude, " advised Jacob Quinn, Trails Coordinator for the Lake Tahoe Basin Management Unit, "and think of everything that comes with it".

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It would most likely sell the gas to oil companies in the Permian Basin, where for three decades CO 2 has been injected into old oilfields to push out an additional 15% of crude.

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