9705 - Laserfiche WebLink

Home Browse Search

GREEN RIVER STUDY PLAN 6 February 2, 2007 4. Flaming Gorge Reservoir will not have water of sufficient temperature and quantity to achieve target conditions in Lodore Canyon in all years. Availability will depend on the hydrologic year, season, and climatic conditions. Although warmer water temperatures in Lodore Canyon may be attainable through flow management, target temperatures may not be achieved in wetter years. 5. Uncertainty exists regarding the responses of nonnative warm-water fishes to the flow and temperature recommendations and subsequent competition or predation effects on the endangered fishes. Monitoring the responses of nonnative fishes to the flow recommendations is needed to ensure benefits to the endangered fishes. 6. There is uncertainty associated with base flow recommendations. Base flows that optimize conditions for endangered fishes will likely vary from year to year because of the effect of antecedent conditions on sediment processes and habitat conditions. To incorporate the effects of antecedent conditions, the recommended mean annual base flows are tied to the hydrologic conditions and the magnitude of the spring peak flow. 7. Effects of base-flow variation on backwater quality are unknown. Variability in base flows occurs at various scales including between years, within a year, between days, and within a day. It was assumed that recommended fluctuation restrictions will protect habitat quality and improve growth, conditioning, and survival of endangered fish. However, the effects of within-day fluctuations on habitat conditions warrant further investigation. The flow and temperature recommendations also identified the need for research and monitoring. In addition to the need to. collect real-time biological and physical data each year to refine how the recommendations are implemented, there is a need to conduct additional research and long-term monitoring of fish responses to address the identified uncertainties (Figure 1). The recommendations suggested that the collection of additional data on endangered fishes and their habitats should focus on the evaluation and possible modification of the recommendations by following an adaptive management process. Research should be conducted by using carefully designed experiments based on hypothesis testing. The flow and temperature recommendations further recognized the need to assess overall responses by the endangered fish populations. These responses include many aspects of the life histories of these species (e.g., reproduction, survival of young, recruitment to adults, etc.), with establishment and maintenance of self-sustaining populations as the goal of recovery (U.S. Fish and Wildlife Service 2002a, 2002b, 2002c, 2002d). Responses by various life-history aspects to flow and temperature recommendations may be observable over a short time span, but because the endangered fishes are long-lived, population responses (i.e., self-sustainability) may be observable only over longer time spans. Short-term monitoring should focus on responses of specific life history aspects, but long-term monitoring must detect differences in population sizes and sustainability. Flow and temperature recommendations and any revisions should be based on sound scientific information for the current status of populations, sediment resources, and other relevant ecological factors.