October 30, 2011

THE HIGH-STAKES MATH BEHIND the West’s greatest river.

The Columbia is a river of colossal proportions: it’s the most voluminous in the West, draining an area the size of Texas and each year passing 60 cubic miles of water to the Pacific Ocean. The 14 structures that harness it are equally formidable: a dam is likely to be the largest manmade object, the most exuberant feat of engineering that you’ll ever see, and the Columbia’s are among the world’s biggest. But as large as the dams are, their margins are minuscule and operating them takes unerring foresight and subtle management: let too much water fill reservoirs and a rainstorm might flood Portland; keep the reservoirs too empty and you’ll parch farmers. Send too much water over a dam’s spillway and you’ll suffocate fish with dissolved gases; send too much through its turbines and you’ll overload the electrical grid.

The difficulties are not widely appreciated.