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The Science of Stream Restoration - NYTimes.com <br />Many hydrologists and geologists say people embark on projects without fully understanding <br />the waterways they want to restore and without paying enough attention to what happens after <br />a project is finished. <br />In part because most projects are local and small scale, it is hard to say exactly how much <br />Americans spend each year to restore rivers and streams. A group of academic researchers and <br />government scientists, writing in Science in 2005, put the figure at well over $1 billion, for <br />thousands of projects. Efforts are under way to bring more academic rigor to the business. <br />For example, the National Science Foundation is supporting construction of a large model <br />streambed in Minneapolis, where researchers will be able to test ideas. Meanwhile, though, "an <br />awful lot of stream restoration, if not the vast majority of it, has no empirical basis," said <br />William E. Dietrich, a geomorphologist at University of California, Berkeley, who studies rivers <br />and streams. "It is being done intuitively, by looks, without strong evidence. The demand is in <br />front of the knowledge." <br />Property owners and local and state agencies restore streams for many reasons, like repairing <br />damage from bridge and dam construction or runoff from farms, subdivisions and parking lots. <br />The damage is visible in reduced water quality, damage to habitats, declines in fish, reduced <br />recreational and aesthetic value and other problems. <br />Some projects use bulldozers to reshape waterways. Others rely on boulders, rock-filled metal <br />baskets called gabions or concrete and other armor to hold rivers in place. Unfortunately, "we <br />have not done enough monitoring to know what works and what doesn't," said Chris Conrad, <br />an environmental engineer for the United States Geological Survey, voicing a widely held view. <br />http://www.nytimes.com/2008/06/24/science/24str...l?_r=1&oref=slogin&ref=science&pagewanted=print (2 of 7) [6/24/2008 12:37:57 PM]