Rotary Screw Traps

Successful Outreach Meetings about Rotary Screw Traps in Downieville and Nevada City

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In late August, SYCRL coordinated two public safety outreach meetings to help our community get answers to their concerns about the placement of two rotary Screw Traps in the North Yuba River. The rotary screw traps are being placed in the North Yuba as one of the initial data gathering steps of the Yuba Salmon Study. 

The Yuba Salmon Study is a collaborative planning and implementation program led by National Oceanic and Atmospheric Administration (NOAA) Fisheries and California Department of Fish & Wildlife (CDFW). The vision of this project is to reintroduce spring-run Chinook salmon to their historical habitat in the upper Yuba River watershed through a phased, science-based, and cost-effective reintroduction project that will inform future Central Valley reintroduction decisions. 

At this stage in the study, the placement of the rotary screw traps is to test the efficacy of the hardware based on the winter flow conditions present on the North Yuba. While the traps will be placed during a low use time of the year (October to May), and interpretive and warning signage will be highly visible at each site, safety concerns still exist. 

Rotary screw traps are specially designed sampling devices to capture downstream migrating juvenile fish such as salmon and steelhead. They are large, cylindrical traps that float on pontoons and are used to trap fish. The traps consist of three main components: a 5-foot or 8-foot diameter cone, a trap box, and pontoons. Inside of the cone, wings are situated in a spiral shape so that as stream currents push against them the cone will rotate on its horizontal axis, much like windmills. As downstream-moving fish enter the mouth of the rotating cone, they are guided to a submerged trap box where the fish are held until they are sampled and then released. The pontoons provide floatation for the cone and trap box assembly. Though relatively low risk, rotary screw traps can be dangerous.  

This is why SYRCL organized the public safety outreach meetings to educate and inform, as well as alleviate the concerns of the community. The first meeting was in Downieville on August 23rd at the Community Center and the next meeting was on August 30th at the Nevada County Library.  

SYRCL Executive Director Aaron Zettler-Mann and SYRCL Fish Biologist Danielle Conway began each meeting with a welcome, an introduction, and a land acknowledgment. Jason Guignard from FISHBIO then explained what the traps are, where they would be located, and what safety measures would be in place. Joanna Lessard from Yuba Water Agency was also on hand to answer any questions about the Salmon Reintroduction Project in the North Yuba. At the Nevada City meeting, Stacie Smith from NMFS was also in attendance to answer questions. At both meetings, representatives from USFS and CDFW were there to answer any questions that might have arisen after the presentation. 

August 23rd Meeting in Downieville

August 30th Meeting in Nevada City

More public meetings were promised in the Fall of 2024 once this initial step in the process is completed. To stay informed about the Yuba Salmon Study, more public outreach meetings, and to ask further questions, go to 

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