Submitted by: Juddson Sechrist, Technical Service Center, 86-68290, 303-445-2198, jsechrist@do.usbr.gov
Proposal ID: 4149
| Title |
| Developing operational criteria information for temperature control device installation at Reclamation facilities through the use of real-time integrated entrainment monitoring systems to improve reliability of water and power delivery. |
| State the Problem. How Do Your Research Outputs Contribute to Achieving Reclamation's Mission, and The S&T Program Mission and Performance Measures? | Reclamation currently spends 8 million dollars annually on recovery efforts associated with the federally endangered humpback chub. The current focus of these efforts are the flow manipulations from Glenn Canyon Dam and mechanical removal of non-native fish in the Grand Canyon near the Little Colorado River confluence. Concomitant with this research, Reclamation is considering the installation of Temperature Control Devices (TCDs')on 2 (units #4 and #6) of 8 turbines at Glenn Canyon Dam. A TCD is a device that can selectively withdraw water from different depths, so that desired downstream temperatures can be attained while still generating power. Proposed cost of this installation is estimated at 71 million dollars. The TCDs will be used to withdraw water from warmer reservoir strata above the thermocline. This warmer water will more closely mimic pre-impoundment water temperatures in the Grand Canyon with the intent to 1)improve optimum spawning conditions for humpback chub, and 2)adversely impact cold-water, piscivorous salmonids that are implicated in the decline of chub populations. Proposed water withdrawals from the warmer epilimnion layers of Lake Powell has potential to complicate recovery of the humpback chub in the following manner: The majority of this reservoir's pelagic species are piscivorous (e.g. striped bass, walleye, carp) and are generally associated with this water strata for a majority of the year. It has been speculated (based on limited data from a 1996 acoustic survey near the Glenn Canyon Dam) that water withdrawals from the epilimnion could entrain 250,000 fish (many of these fish being striped bass) per week (Mueller and Horn 1999). Further, Arizona Game and Fish have proven that these piscivorous species can be passed alive through the dam's turbines. Currently, water withdrawal at Lake Powell occurs in the reservoirs hypolimnion (deep, cold, oxygen poor water with very low fish densities) to maintain downstream trout fisheries at Lee's Ferry and below. This, coupled with poor survival through facility turbines has likely been responsible for the absence of piscivors (other that trout) in the reservoirs tail-race. Water withdrawal from Lake Powell's epilimnion has potential to add many more predators into a river that will be warmer and much more suitable to their survival and reproduction. Humpback chub densities (believed to be less than 4000 fish over 150 mm) would undoubtedly be impacted, and would in effect prolong non-native eradication efforts indefinitely, with little hope of de-listing this species. The long-term costs to Reclamation and its stakeholders could be enormous (over and above the 8 million dollar annual outlay of resources currently allocated.) This proposal seeks to establish base-line data on distribution and density of pelagic fish proximate to Glenn canyon Dam, monthly. This will determine the potential, if any, for fish entrainment. Further, the proposal seeks to pursue methodologies to provide real-time fish distribution and density information to Glenn-Canyon Dam operators should the TCDs be installed. This would provide decision-support that would allow a desired water temperature strata to be accessed at a time and/or depth when these potential predators have low probability of being entrained. Literature Cited: Mueller, G., and M. J. Horn. 1999. Description of the pelagic zooplankton and fish communities of Lakes Powell and Mead. Open File Report 99-109. U.S. Department of the Interior, U.S. Geological Survey, and U.S. Bureau of Reclamation. Prepared in Cooperation with Glenn Canyon National Recreation Area. Lake Mead National Recreation Area, Utah Department of Wildlife Resources, Arizona Game and Fish and Nevada Department of Wildlife. |