Derby Dam Fish Screen

Engineering services, Final design, Environmental/permitting, Engineering during construction, Testing & commissioning
Professional services
Truckee River, Nevada
Bureau of Reclamation
Farmers Conservation Alliance
why it matters

Fish passage at Derby Dam was a priority conservation project for Pilot Peak Lahontan Cutthroat Trout (LCT), Oncorhynchus clarkii henshawi, recovery for more than two decades. The USFWS and Reclamation worked collaboratively to implement the protection of the Derby Dam passage project. McMillen designed the fish bypass system, including the largest horizontal fish screen in North America, to allow previously declining fish populations to pass downstream of the headworks of the Truckee Canal and not becoming entrained in the irrigation canal. The project also included an upstream fishway providing listed Pilot Peak LCT and Cui-ui, Chasmistes cujus, access to migration, spawning, and rearing grounds that have been blocked for over a century. Numbers of LCT migrating in the Truckee River from Pyramid Lake are increasing every year since the completion of this project.

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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.

"Farmers Conservation Alliance has worked with McMillen on the Derby Dam Fish Screen Project and could not be more pleased with the partnership. Successful fish screen and passage design projects require an engineering firm that can listen to the needs of all involved parties while fostering a collaborative atmosphere...They are quick to respond to communications and they are willing to find solutions when needed from the design phase through project implementation. Even better, McMillen understands the value of being on time and on budget.”

Alexis Vaivoda

Program Manager, Farmers Conservation Alliance

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