BOULDER COUNTY — A coalition of environmental defense groups are appealing a decision by federal agencies allowing Denver Water to expand Gross Dam to more than triple its current capacity. The coalition includes Save The Colorado, The Environmental Group, WildEarth Guardians, Living Rivers, Waterkeeper Alliance Inc., and the Sierra Club; it filed a notice of appeal in federal court Monday morning, asking the U.S. 10th Court of Appeals in Denver to review a district court judge’s dismissal of the original complaint. Gross Reservoir is a 440-acre reservoir just west of Eldorado Canyon State Park at the southern end of Boulder County. Denver Water received final approval last year to raise the existing dam from 340 feet to 465 feet and more than triple the reservoir’s capacity from 41,811 acre-feet to 114,000.