8167 - Laserfiche WebLink

Home Browse Search

Other Abiotic Factors Affectinq the Dolores River Tailrace Fishery The managed-spill of 1992. together with the prolonged high discharge of 1993 has greatly benefitted the Dolores River tailrace fishery. Observation of the stream channel and substrate during the 15 day period from June 29 through July 13 (at the end of the 1993 managed spill) indicate that most of the fine sediment had been flushed from the river channel. The river is largely a free- stone stream throughout much of its reach from the dam to at leas~ the Dove Creek Pump Plant with good aquatic invertebrate populations evident. The increases in the 1993 density, biomass, and body condition factors of the trout population are indicative of a stream trout fishery well on the road to recovery from the less than adequate habitat conditions of the three year period between 1989 and 1991. CONCLUSIONS Overall, the Dolores River and the aquatic biota that support the trout fishery downstream from McPhee Dam may well be in the healthiest condition since reservoir operations began in 1984. However. the stream has the potential to support a much greater fish community than it does at present. Further improvement depends upon a number of factors, many of which are under man's control. These incl~de 1) continued availability of water over the long-term. 2) allocation of more water for the maintenance of the stream ecosystem. 3) wise arid judicious use of water allocated for the stream ecosystem (especially during periods of extended drought), and 4) a recognition of and commitment to the concept that a 20 cfs discharge during the spring to fall period is incompatible with the maintenance of a healthy coldwater fishery in this river. ,.J LITERATURE CITED Lagler, K.F. 1952. Freshwater fishery biology. 2nd edition. Brown, Dubuque, Iowa. Nehring, R. B. 1992. Dolores River fishery monitoring studies April - October 1991. Colorado Division of Wildlife report to the U.S. Department of the Interior, Bureau of Reclamation - Durango Projects Office. Contract No. 1- FC-40-10460. Modification No. 001. 43 p. Nehring, R. B. 1991. Aquatic winter habitat monitoring study and assessment of interactions between stream discharge, aquatic habitat, and the trout population of the Dolores River below McPhee Dam. Colorado Division of wildlife report to the U. S. Department of the Interior, Bureau of Reclamation - Durango Projects Office. Contract No. 1-FC-40-10460. 29 p. Seber. G. A. F., and E. D. LeCren. 1967. Estimating population parameters from catches large relative to the population. Journal of Animal Ecology. 36:631-643. -20-