FINAL REPORT UPPER COLORADO RIVER BASIN RECOVERY IMPLEMENTATION PROGRAM FEASIBILITY EVALUATION OF NON-NATIVE FISH CONTROL STRUCTURES Prepared for: Colorado River Water Conservation District Glenwood Springs, Colorado Prepared by: William J. Miller Miller Ecological Consultants, Inc. 1401 Riverside Ave., Suite 3 Fort Collins, Colorado 80524 with assistance from: Doug Laiho Ayres Associates 3665 JFK Parkway, Bldg. 2, Suite 300 Fort Collins, Colorado 80525 February 18, 1997 MILLER ECOLOGICAL CONSULTANTS, INC. EXECUTIVE SUMMARY Non-Native fish have been identified as an impediment to recovery of endangered fish in the upper Colorado basin, the impediment being habitat competition and predation. Control of non- native species has been identified in the recovery action plan as one item that needs to be accomplished to move toward recovery. This report is a feasibility evaluation of installing control structures to eliminate escapement from off-stream reservoirs in the upper Colorado basin. The reservoirs evaluated in this study are Elkhead Reservoir near Craig, Colorado, and Highline Reservoir near Loma, Colorado. This study also serves as a source of reference information and an example of how control structures might be implanted at other similar facilities throughout the upper basin. Objectives of the report were to examine two different levels of control. The first objective examined full exclusion of egg and larger life stages at Elkhead and Highline Reservoirs. The exclusion facility would handle flows up to the 100 year flood event with as close as possible to 100% efficiency. The second objective was to evaluate installing a control structure that limited escapement to the current industry practice. That practice is approximately 90% effectiveness and screen openings no smaller than 3/32 inch. Also, the facility would handle flows up to the 100 year flood event. For frame of reference, a no action alternative was also looked at to provide a basis for change in fish community and a perspective on effectiveness of the full exclusion and current industry practice alternatives. Elkhead Reservoir is located on Elkhead Creek which is tributary to the Yampa River. Elkhead Creek has routed flows up to 2,100 cfs and is an unregulated watershed. The reservoir spills annually and is rarely drawn down for release of water for municipal or irrigation use. Highline Reservoir is located on Mack Wash which is a tributary to the Colorado River. Highline receives all inflow, except for local storm runoff, as administrative spills from the Highline diversion canal. Flows into the reservoir and out of the reservoir generally are less than 100 cfs. The watershed upstream of Highline Reservoir on Mack Wash is small and the high flows would be the result of storm runoff, especially summer thunderstorms. Target species evaluated for this control structure feasibility study included channel catfish, smallmouth bass and northern pike. These species are present in both reservoirs with the exception of northern pike which is present only in Elkhead Reservoir. Currently, smallmouth bass reproduce in the reservoirs. Channel catfish are suspected of reproducing only in Highline Reservoir. With these species, the life stages of interest include everything from egg size and larger. Other warm water species present in the reservoirs include black crappie and largemouth bass. These species can escape but are not likely to successfully reproduce and recruit to the riverine fish populations. Therefore, these latter species were not the primary focus of the evaluation. Control techniques selected for the target species also should control the non-target species. Evaluations started with a literature review and personal interviews on various screening and fish passage facilities. The interviews were with experts in the field of fish passage, specifically related to design, construction and operation of mostly downstream migrant facilities. Structures evaluated in the present study did not include a fish bypass. The structural option designs were configured so that there would be no bypass of non-native fish downstream and result in handling of those fish for either disposal or transport back upstream to the reservoir. This is a substantial Control Structure Feasibility Evaluation i Miller Ecological Consultants, Inc. February 18, 1997 variation from the usual downstream passage facilities. Most screening facilities have some sort of safe passage feature for the fish to move safely around the dam or diversion structure and back to the receiving stream downstream of that structure. This project has several features which make the selection of feasible control options unique. The current technology includes both physical and behavioral techniques to control fish passage. In this case, the behavioral techniques will not stop the passive life stages that may be present and are only marginally effective on controlling active life stages. For these reasons, behavioral techniques were not considered feasible control options at either Elkhead or Highline reservoirs. Physical control devices include several types of screening devices. Since the objective of this study is to control escapement, the best location for controlling the fish is within the reservoir. Any device placed downstream of the reservoir would require construction of a stream channel and physical screening facility large enough to protect to the maximum flow event. Further, the facility would need to be designed to function at the current industry standard for the full range of flows. The wide range of flows from flood flows to near zero would be very difficult to protect with one facility. This may require one facility designed to work at high flows and another to work at the low flows. Further, any fish that get to the downstream facility are already moving toward habitat occupied by the endangered fish species. Any facility downstream of the reservoirs also would require a fish bypass or collection facility and some type of fish handling or disposal. All of these factors eliminate the downstream location as a feasible option. Physical facilities designed for in-reservoir control include both high velocity and low velocity screens. Both the high and low velocity screens constructed in the reservoir would have to be designed to operate for the full range of flow conditions. High velocity screens include Eicher and Modular Inclined Screens. Both of these screen types are intended for use within a reservoir outlet or penstock and both require fish bypass. To meet the criteria set for this study, the reservoir outlets would have to be reconstructed to a size that would pass all flow up to the 100 year event and include the screen. The fish bypass would require a fish collection facility that could retain any bypassed fish for either disposal or transport back to the reservoir. This would require additional operation and maintenance funds for the life of the project. This additional cost in excess of the capitol cost for reconstruction of the outlet works and requirement for fish handling makes these screen types lower priority for selection than types that have no fish bypass or fish handling. Low velocity screens include traveling and fixed screen types. The traveling screens all require considerable operation and maintenance costs. In addition, there is a possibility that escapement can occur as screen seals wear. The gap between the screen and the seal could exceed the 3/32 inch opening for the criteria for this project. This would not meet the exclusion criteria for the project. The traveling low velocity screens would require a large screen face relative to the flow rate ratio and do not work in a submerged location. The large size would require considerable capitol cost for construction of the civil works associated with these types of screen and high annual operation and maintenance costs. Therefore, traveling screens were not selected for further evaluation in this project. Fixed screens are generally designed for low approach velocities to eliminate fish impingement. Most fixed low velocity screens have a traveling brush to clean the srceen face of debris. Any such mechanical device requires additional maintenance over an non-mechanical system. Control Structure Feasibility Evaluation ii Miller Ecological Consultants, Inc. February 18, 1997 Therefore, fixed screens that can be installed in a submerged location without mechanical cleaning were rated as the best potential device for this project. The two objectives for this project require two different screen alternatives, one that prevents escapement of all life stages and the second that protects to the current industry standard. In this project, impingement was deemed an acceptable consequence of in-reservoir protection. This allowed the evaluation of higher (2 ft./sec.) velocity fixed screens in this project for both objectives. In addition, for the protection to current industry practice option, a secondary protection mechanism was evaluated in each reservoir in addition to the fixed screens to protect at high flow events. Control structures are feasible at both reservoirs. The best location for the structures is on the primary outlet to the reservoir. To meet the criteria for full exclusion set in this study, the primary outlets for each reservoir would be reconstructed and enlarged to safely discharge flows up to the 100 year event. The best screen type for these reservoirs is a fixed plate screen that functions while submerged. This is a cylindrical screen type with a pneumatic backwash system for cleaning. In addition, the reservoir level would be reduced by 1-3 feet below the spillway crest to prevent spills and escapement. There would be no additional screening protection on the spillway for this alternative. The control type that meets the criteria for current industry practice is a cylindrical screen on the primary outlet in combination with a barrier net placed in front of the spillway. The primary outlet would require enlargement but would not pass all flows up to the 100 year event. High flows would be released through the service spillway of the reservoir.