Concrete is increasingly sounding old school. The idea makes sense: build a concrete channel through your city, to get the water as quickly as possible from the mountains to the sea, minimizing the mischief it can do in the interim. But such engineering efficiency comes with a cost, as the folks in Pasadena, Calif., (where I first wrote about water a couple of decades ago) are finding out (story from the Pasadena Weekly):

Restoring water courses to a more natural state, said Kwan, will allow more water to percolate into the ground rather than flow into the Los Angeles River and spill into the Pacific Ocean.

(h/t aquafornia, Wikipedia picture of the old Devil’s Gate area in Pasadena’s Arroyo Seco prior to all the concrete)