Client Name: Garco Construction
TD&H was selected to provide surveying and construction staking services for this $50 million project which was funded by the Bonneville Power Administration (BPA) through the Columbia River Fish Mitigation Program.
The current juvenile fish survival rate for fish that pass over, around, or through Lower Granite Dam each year is about 95-96%. A 1% increase in the survival rate is significant when you consider the millions of fish that make the trip each year. The most evident improvement constructed as part of the U.S. Army Corps of Engineers Lower Granite Lock and Dam Juvenile Fish Facility Upgrade Phase 1a project is the 2,700-foot-long elevated, screen-covered flume. The screened flume will allow the juvenile fish to make the journey from the collection channel in the dam to the juvenile fish facility under natural light and at a leisurely grade of approximately 4%. The new elevated channel will eliminate the turbulent flows encountered in the downwell and upwell of the current underground pressurized pipe system, which will reduce stress and lower potential for injury. This, and numerous other improvements constructed as part of the project, will fulfill the primary goal of the Endangered Species Act to improve the survival of listed Salmon and Steelhead migrating through the hydro system.