METHOD FOR DETERMINING MINIMUM POOL REQUIREMENTS TO MAINTAIN AND ENHANCE SALMONID FISHERIES IN SMALL WYOMING RESERVOIRS

Methods for determination of minimum pool levels in reservoirs that co nsider sport fishery values are being sought by managers. We developed a technique for assessing the effects of incremental changes in minim um pool levels on potential salmonid abundance in small (<100 surface hectares at full pool) reservoirs in Wyoming managed for irrigation an d municipal water supplies. The method has two components. One compone nt is used to determine the minimum pool level needed to eliminate the risk of overwinter loss of salmonids due to low dissolved oxygen conc entrations. The other component predicts the potential biomass of salm onids in reservoirs as a function of water depth and total dissolved s olids concentration of the reservoir water. Application of the method is demonstrated for two reservoirs in Wyoming.