An experimental procedure was developed to analyze the ability of a highway culvert to pass fish. By using a visual technique, the swimming performance of Arctic grayling (Thymallus arc t icus) was monitored in Poplar Grove Creek, Alaska. The highway culvert is 110 ft long and 5 ft in diameter, and is inadequate for fish passage if the Alaska Department of Fish and Game criteria are applied. The drainage area experienced a 20-year flood (Q2ol during spring 1985. Excessive pipe velocities prevented the fish from passing the culvert for 8 days. A large portion of the fish in the downstream scour pool were removed by sport fishermen during the period of high flow. Approximately 78 percent of the fish attempting to swim through the culvert were successful when the outlet velocity dropped to 7.3 ft/sec (fps) and about 95 percent swam through when the velocity receded to 6.9 fps. A request for information on fish passage was sent to US and Canadian highway departments and fishery agencies. Forty-four states and all Canadian provinces responded. Twenty states reported that they generally do not have problems with fish passage through highway culverts. Eighteen highway departments reported having a good working relationship with resource agencies when addressing fish passage prQblems. These 18 states commonly suggested that (a) early coordination should occur between highway and resource agencies during the design phase,(b) culvert inverts should be depressed approximately 1 to 2 ft below the natural stream bed,(cl culverts having slopes greater than 1 percent should have a baffling system, and (d) the remaining culvert volume should be able to handle approximately a Q50 discharge.

5 Fish populations are widely distributed throughout Alaska and must often pass through highway stream crossings. These crossings can be crucial to the seasonal migration of fish populations because rnodif icatiQns to the natural stream flow conditions may impede access to feeding, spawning, or overwintering habitats. The proper design of highway culverts is essential to facilitate the passage of fish. Design criteria for culverts should be well defined to ensure fish passage but should still consider the hydrological conditions of the stream site, difficulty of installation, and economics of design and construction.