Laserfiche WebLink
The Science of Stream Restoration - NYTimes.com <br />spread it on their fields. <br />And because there are no boulders or other armor involved, he said, "cost-wise we compete <br />pretty well." <br />When the work was done, a result was a shallow sheet of water moving over a graveled bed. The <br />water was lined with native plants like sedges, vervain and verbena, sprouted from seeds <br />buried under the silt for more than ioo years. One spot was deepened to create a cool refuge <br />for fish, and nearby, dozens shimmered in the water. <br />But an approach that works in one place may fail in another. And some critics say restoration <br />to some pristine ideal is simply impractical. Perhaps the most prominent is David L. Rosgen, a <br />hydrologist who runs Wildland Hydrology, a consultancy in Fort Collins, Colo., that designs <br />restoration projects and offers courses on his restoration theories. <br />"It is impossible to try to restore streams to some condition that is totally different, before we <br />showed up, before we caused disequilibrium," he said in an interview. "You know how many <br />valleys have aggraded because of those old mill dams? You are talking about hundreds of <br />millions of cubic yards of sediment." <br />Dr. Rosgen devised a system that classifies rivers and streams, and prescribes restoration <br />remedies according to several qualities, including water flow, channel characteristics and <br />sediment load, and takes into account how human activity affects the landscape. By now, he <br />said, more than 14,000 people from state and federal agencies and conservation groups have <br />taken his courses and many have used his ideas to good effect. <br />But he, too, has his critics. Dr. Montgomery called Dr. Rosgen's classification "a very clever <br />http://www.nytimes.com/2008/06/24/science/24str...l?_r=1&oref=slogin&ref=science&pagewanted=print (5 of 7) [6/24/2008 12:37:57 PM]