South Fork John Day River Habitat Enhancement Project. Annual report 1986, 1987 and Final report

摘要

The South Fork John Day River (SFJDR) contains important wild summer steelhead habitat. Adult fish annually return to the drainage to spawn. All tributaries accessible to steelhead are used for spawning. Additionally, juvenile steelhead rear in the SFJDR and its tributaries from two to three years before migrating to the ocean. The role of the SFJDR in rearing juvenile steelhead, particularly from age 1+ to smolt, is vital to the system as a whole. Many, if not all, of the tributaries produce juveniles in numbers exceeding the stream's capacity to rear to smolt. These fish migrate to the SFJDR and are reared to smolt there. Factors limiting steelhead production in the SFJDR are: Poor quantity and quality of pool habitat; low summer flows; high water temperatures; and excessive sediment load. During September 1986, 1,500 boulders were placed in 14 reaches of the South Fork John Day River approximately between RM 14 and RM 25. A number of smaller boulders were also placed by the contractor rather than return them to the rock pit. The boulders were placed in a variety of configurations, each determined as best fitted to specific site features (such as, depth, flow, velocity, bank condition, existing or potential riparian cover. It is estimated this project will provide rearing area for an additional 7,500 summer steelhead smolts.