Derby Dam was constructed in 1905 to divert irrigation water through the Truckee Canal. Over time, the dam's presence has contributed to declines in Pilot Peak Lahontan Cutthroat Trout and Cui-ui. There have been significant efforts to help restore these populations.
McMillen served as the design lead for the fish screen, which is the largest in North America, passing up to 600 cfs. It uses Farmers Conservation Alliance’s patented design to screen water supply while bypassing debris and fish back to the river. The system uses numerous isolation gates to de-water specific screens, including seven sluice gates and five weir gates. The fish bypass includes two fish return flumes to pass fish and bypass flows to two roughened channels which converge upstream of a velocity barrier intended to exclude fish from entering. Our team engineered a log jam downstream of the velocity barrier to dissipate energy and diminish fish attraction flows so that migrating fish do not attempt to ascend the fish bypass facility.
During construction of the screen, a bypass channel allowed reliable water deliveries to downstream users via the Truckee Canal to support the community’s farming season. The bypass channel also supplied water to the Stillwater National Wildlife Refuge wetlands and the Pyramid Lake Paiute Tribe. Now that the screen is complete, the bypass channel provides flexibility during screen maintenance.
Our team was responsible for the following work:
- Surveying
- Hydraulic analysis with a 3D model
- Geotechnical investigations including seismic loading, liquefaction potential, and differential settlement between the existing dam and new structure
- Sediment management including a sediment flush system plan and drain piping
- Civil design, including an access road, a grading plan with LiDAR contours, erosion and sediment control, retaining walls, parking, and piping
- Structural engineering for all concrete structures and structural steel support for the fish screen
- Electrical design including PLC for the gates, site lighting, a one-line diagram, flow meters, telecommunications, and video monitoring
- Mechanical systems design for gate operation
- Design of a supplemental bridge and a flow monitoring station
- Demolition of existing structures
- Permitting support
- Advancing 30% design drawings to 100% construction drawings
- Cost estimates
- Engineering support during construction
- Project close-out support
The fish screen was commissioned in 2021 and is successfully operating as expected. The project has received multiple awards from industry titans, including Associated General Contractors of America, Engineering News Record, and the International Partnering Institute.
