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Construction workers pump con- crete Into Craig's diversion dam, Ph0108 COUrt8&y 01 'd'le City of Craig Craig's diversion dam Is designed to back water up to 8 minimum depth of 18 Inches to keep the city's municipal water Intake pipe submerged. Diversion dam benefits, rare fish, water development By Fred Quanarone Public I nformation Specialist Colorado Division of Wildlile Water development and endangered fish in the Yampa River have both benefitted from an innovative water diversion dam constructed lhis winter near Craig, Colo., with the U.S. Fish and WlIdlife SeNice's approval. The dam, built to divert water to the city of Craig and be compatible with needs of recreationists and endangered fish, represents a model project for efforts to recover the fish while pro- viding for future water development. "Craig's diversion structure shows that certain kinds of water develop- ment can be made compatible with the needs of endangered fish,~' said John Hami1\, director of the Recoyery Program for Endangered Fish of the Upper ColoradO River Basin, 'This is the first sucoessful attempt at building a structure to provide for fish passage and water diversion, and I think it will open up opponunities in other areas." For its efforts, the City of Craig won a national award in April for "excellence in environmental engi~ neering" from the American Academy of Environmental Engineers. Previously, low Yampa River flows jeopardized the city's ability to divert river water to its municipal water treatment plant. Grayel diversion dams were built across the Yampa. It was a stopgap measure nobody liked. "We had a permit for five years to do the temporary diversions," said Jim Pankonin, Craig public works directot "We made an agreement with the SeNice that if we were in the river more than three times in lOOse five years, we'd look at a more permanent solution" To find that solution, Craig hired FLO Engineering of Breckenridge, Colo., to build a penrianent structure. Designing the structure presented special challenges, according to Bill Fullerton, R.O Engineering president. ''The biggest challenge was produc- ing a fish passage design that satisfied the criteria of the various agencies involved," Fullerton said. "We needed a design to convince the agencies that' endangered fish could pass through the structure, We worlced closely with the Fish and Wildlife SeNice to make sure eyerybody was confident the structure would work." Once the structure was completed, the City of Craig contracted with BioWest, a research firm in Logan; Utah, to study fish movement across the diversion. Between April and October 1992 the firm tagged more than 1,300 fish and found that just oyer 2 percent of the fish moyed across the diversion, "It's our feeling that the structure 5 doesn't impede movements of fish at the flow ranges we observed," said Bill Masslich of BioWest. The Fish and Wildlife Service concurred with the findings and gave the dam its stamp of approval. Looking more like a natural riffle than a river-wide diversion dam. the rock structure is broken up by a 30- foot gap or channel. The channel allows not only fish, but also boaters, to moye up and down the river. Three control structures or humps in the bottom of the channel vary flow and create slack waters where fish can rest as they move through. "You don't see a dam," Pankonin said. "All you see in the river is a low riffle cascading over rock. It's a vety natural looking structure." The Colorado River Water Conservation District now is outlining a plan to examine and modify older diversion dams in the Yampa River and to make them more efficient and compatible with endangered fish and river recreation. According to Craig City Manager Don Birkner, the new diversion structure may serve as a model for other structures. "We're confident we've done somelhing here in Craig that can haye impacts on the rest of the state and the the Recovery Program," Birkner said.