Survival of Fish Impinged on a Rotary Disk Screen

An impingement survival study was conducted to determine 48-h survival of fish impinged on a modified rotary disk screen equipped with fish protection features. The rotary disk screen was installed for a technology evaluation at the cooling-water intake structure of the North Omaha Station located on the Missouri River in Omaha, Nebraska. Hatchery-raised fish and native fish collected from the Missouri River were released in batches into the rotary disk screen bay and collected with a system that was constructed to recover fish from the screen's vacuum system. That system was designed to remove fish from the rotary disk screen and return them to the river. Screen performance was assessed in April and August, representing spring and summer environmental conditions. The 48-h survival rates of hatchery-raised fathead minnow Pimephales promelas, channel catfish Ictalurus punctatus, and bluegills Lepomis macrochirus and a group of mixed native species approached 100%. Survival rates were not statistic...