The US Bureau of Reclamation (USBR) will release water through the river outlet works at Flaming Gorge dam on the Green river, Utah, to accommodate a series of short-term endangered fish experiments.
The flows will enable scientists working with the Upper Colorado River Endangered Fish Recovery Program (UCREFRP) to monitor the effect of high flows downstream of the dam.
Green river flow levels of 400m3/sec, 450m3/sec, and 500m3/sec measured at Jensen, Utah, have been requested by the UCREFRP scientists. In order to reach this level, USBR is likely to release water at the full capacity of the Flaming Gorge power plant and the river outlet works. Releases from the dam could reach approximately 240m3/sec. Releases will combine with flows from the Yampa river and should achieve the requested flow levels.
USBR is currently monitoring the Yampa and waiting for the most prominent peak to occur. USBR will begin making power plant capacity, and possibly bypass releases, when this occurs. It is likely that these test releases could begin within the next two weeks. On average, the Yampa historically peaks on 23 May.
Recreational uses of the river should not be impacted. The river launch ramp below the dam at Little Hole and Indian Crossing will remain open.
In addition to the fish studies, it is hoped that high flows will also move sediment out of the river below the dam that has impacted the high-value trout habitat. Scientists also are interested in observing the impacts of high flows on the New Zealand mud snail, a source of increasing concern in the river.
UCREFRP scientists will be releasing fish larvae and neutrally buoyant beads – which simulate fish larvae – into the Green river at specific flow levels, and then recapturing the beads at various key locations downstream. The information obtained will be valuable in better understanding the role and function of flooded habitats in endangered fish recovery, including the drift of larvae into backwater habitats. It will also provide information on the effectiveness levees breeches that provide access for endangered fish to floodplain nursery resistant habitats.
Flaming Gorge reservoir is expected to come within 4.8m of refilling at the completion of the spring runoff period in July 2005.