The FishWorks Shop Fish Passage An Educational Series Presented by the R&E and STEP Programs I n order for fish to utilize habitat in a river or stream, fish need to be able to get there. While that may seem simple enough, over the last two centuries people have been building barriers to fish throughout the country, especially dams, irrigation diversions and roads. Cumulatively, these barriers have prevented many native fish species from accessing hundreds of thousands of miles of historical habitat in the U.S. These barriers have had a significant impact in Oregon since so many of our streams host runs of anadromous fish such as salmon, steelhead, Pacific lamprey and sea-run cutthroat trout that have been cut off from significant amounts of spawning and rear- ing habitat. Resident species such as trout also suffer from stream barriers. Impassable barriers affect how much habitat those fish are able to utilize and also limits genetic exchange with other fish of the same species living in different parts of the stream and is important for genetically healthy populations. But in recent years, a great effort has been made to improve fish passage on Oregon streams and rivers, which includes repairing old passage facilities that no longer work, upgrading others with the latest technology and creat- ing passage where there was none. In addition, since 2001 Oregon law requires that “the owner or operator of an artificial obstruction located in waters in which native migratory fish are currently or were historically present must address fish passage requirements” when improving, adding to, obtaining new permits or abandoning those artifical obstructions. Through ODFW Fish Passage Program partnership with the R&E and STEP programs, ODFW continues to be very involved in providing fish passage in the state’s rivers and streams. Dams Many, but not all, large dams were constructed with fish passage facilities. Even then, there can be challenges. Some of the most well known examples are the federal hydropower dams on the Columbia and Snake rivers. Although they have fish ladders that successfully pass upstream migrating salmon and steelhead, difficulties are encountered by smolts as they migrate downstream to the ocean. The slack water in the reservoirs above the dams can slow the smolts’ journey to the sea and others die when they are sucked into the dams’ turbines. Solutions to those problems include increasing spill during critical smolt migration periods and using screens and other diversion structures to move the small fish around the dam and into the river below. In other situations, the best approach may be to remove the dam from the river altogether. Such is the case with the Savage Rapids Dam on the Rogue River. Although it has a fish ladder, it never worked very well and in at least one incident several years ago, thousands of salmon smolts were killed when the system malfunctioned. Savage Rapids Dam is slated for removal in 2010 and the irrigation water it diverted will be drawn from the river by pumps. Providing fish passage on large dams is often a very technical process that requires detailed negotiations with dam owners, various government agencies and other parties. ODFW technical staff are major participants in these negotiations. Irrigation Diversions Small irrigation diversions are much more numerous than larger dams on Oregon streams and cumulatively have a substantial impact on fish populations. These are typically small dams that are closed off during the irrigation The Savage Rapids Dam on the Rogue River will be removed in 2010 to improve fish passage. Fall 2008