Effectiveness of electrical fish barriers associated with the Central Arizona Project


R W. Clarkson

Publication Date



barriers, fish barriers, canal, entrainment, strategy, upstream, design, design criteria, protection, monitoring

Journal or Book Title

North American Journal of Fisheries Management


The Central Arizona Project (CAP) canal delivers Colorado River water into the GilaRiver basin. During its planning and construction, issues arose regarding the unwantedentrainment and transport of nonindigenous fishes and other aquatic biota into, through, and outof the canal. One control strategy was the emplacement of electrical fish barriers on two CAPdistributary canals to prevent fishes from moving upstream into the Gila River drainage. Theoperation, maintenance, and effectiveness of these barriers are described for the period 1988-2000. Documented outages totalled more than 100 h, representing less than 0.001% downtimesince installation. It is nearly certain that outages allowed immigration by undesired fish(es).Immigrations that occurred when the barriers were operating according to design criteria indicatethat the barriers do not totally block the passage of upstream-migrating fish. The proximatesources of electrical barrier outage included component damage from lightning strikes,component breakdowns, failure to adhere to component maintenance and replacementschedules, failure to incorporate adequate protection and redundancies to certain systemcomponents, inadequate training of personnel, and unknown causes. Known outages of remotemonitoring systems (which are necessary to document outages and understand the potential forundocumented barrier outages) totalled more than 400 d, representing about 3% of the period ofbarrier operations. The complexity of electrical barrier systems and the problems such intricacycreates for operation and monitoring may always preclude absolute effectiveness. Additional refinements to system components, personnel training, and operation procedures may reducebarrier failures but add further to that complexity. Management agencies will have to determinethe cost-effectiveness of such refinements.





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