Projects by Discipline / Environmental Science

Coal Creek Fish Passage

Coal Creek is a Front Range stream that originates in the foothills north and west of Denver.  By the time Coal Creek reaches the Town of Superior, it is making the transition from a stream dominated by cold water fish species to one dominated by warm water fish species.  Between the mouth of the canyon at Colorado Highway 93 and the Town of Superior are numerous instream diversion structures that effectively block fish movement and remove a significant amount of water from the creek.  Fish present include the Longnose Dace, Flathead Minnow, Creek Chub, Central Stone Roller, Johnny Darter, White Sucker and Rainbow Trout.  A large part of the lands adjacent to Coal Creek have come under public control and beginning in 1999 a program of restoring aquatic and riparian ecosystems was initiated.  This program addresses both instream flow issues and physical characteristics of the creek.  A year 2000 instream flow study (also completed by Hydrosphere) characterized natural flow patterns and irrigation flow removals in order to identify target instream flows needed for native biodiversity and integrity of aquatic and riparian ecosystems.  In 2003 private funds became available to address physical restoration.  These funds were used to correct fish movement barriers created by irrigation diversion structures.

These structures on public property and positioned in close proximity to each other were targeted for modification.  Hydrosphere worked with City and County personnel to develop plans for fish passage at these three structures.  The Eggleston No. 2 Ditch Diversion had been abandoned some years previously and the water rights transferred to other diversion locations.  As such, it was decided to completely remove this 6-foot high concrete structure and restore the creek to its natural gradient.  The Eggleston No. 1 Ditch Diversion and the Hake Ditch Diversion remain active diversions, therefore, structural fishways were provided.  The Eggleston No. 1 Ditch Diversion, a 4-foot high concrete structure, was modified by narrowing a stop log section of the dam and constructing a grouted rock, roughened chute fishway, centered on the diversion near its right edge.  The Hake Ditch Diversion, a 3.5-foot high concrete rubble structure, required full reconstruction.  A new headgate and grouted rock diversion were designed.  The grouted rock diversion contains a grouted rock, roughened chute fishway through its left edge, immediately next to a new sand gate.