Thirty years ago, the best thinking on urban stream management prescribed cement as the solution to flooding and other problems of people and flowing water forced into close proximity. Urban streams were perceived as little more than flood control devices designed to hurry water through cities and neighborhoods with scant thought for aesthetics or ecological considerations. Stream restoration pioneers like hydrologist Ann Riley thought differently. She and other like-minded field scientists imagined that by restoring ecological function, and with careful management, streams and rivers could...