US rivers and lakes are shrinking for a surprising reason: cows

Cattle-feed crops, which end up as beef and dairy products, account for 23% of water consumption in the US

As a fifth-generation rancher in Colorado, Paul Bruchez knows the value of water. Not only does he raise cattle irrigated by the Colorado River and its nearby tributaries, Bruchez runs a fly-fishing business on those same streams.

My income, my life, requires a reliable water resource," he said. But since moving to northern Colorado two decades ago, the Colorado River has shrunk by an average of 20% compared to last century. Climatic conditions are one culprit - the area is suffering the worst regional dry spell on record. But there's another big problem.