I am working on a project that will replace some anchor cables on the two floating bridges that cross Lake Washington in Seattle, Washington. The project will use a pair of divers to replace these cables in water from 40 to 200 feet deep. Lake Washington is the largest lake in Western Washington, and supports a number of salmonid species, including anadromous sockeye. Adult sockeye are known to find thermal refuge at 50 to 90 feet deep during the warmest part of the summer, and this season the population is expected to be 105,000. A question has arisen on the potential impact that two divers would have on these fish, and I am at a loss to find a source of information. Does anyone know, or can anyone provide best professional judgment, on the potential impact of a pair of divers moving vertically through the thermal refuge layers where sockeye would be dispersed?
Brian Bigler NW Region Biology Program Manager Washington State Department of Transportation Seattle, WA Direct: 206-440-4519 Cell: 206-919-1610 FAX: 206-440-4805
|