Napa River Rotary Screw Trap Open House 2019

On Sunday May 5, 2019 the Napa County Resource Conservation District (RCD) hosted an Open House event for approximately 50 interested members of the public at the Napa River Rotary Screw Trap.

For nearly a decade, the RCD has been using the rotary screw trap — a fish collection device — to monitor fish populations in the Napa River Watershed, with particular focus on steelhead and Chinook salmon. The trap operates seven days a week from approximately March 1st through June 2nd during the juvenile fish migration period.  The trap captures juvenile steelhead, Chinook salmon, along with several other native and non-native species as they swim downstream. With the help of volunteers, RCD staff counts, weighs, and measures the fish before they are returned back to the river. Certain fish are also tagged and have small genetic samples taken, which allows scientists to track and monitor the steelhead and salmon populations. The data collected since 2009 has helped biologists and resource managers better manage steelhead and Chinook salmon within the Napa Valley Watershed.

The Open House gave visitors a chance to see the trap in action, discover the diversity of species that live in the Napa River, and learn about the health of the watershed.


WRA, Inc. has provided seasonal biological services to the Napa RCD, including trap monitoring, since 2017. WRA’s Stewart DesMeules (top right) and Jemma Williams (left and bottom right), talk to participants of the RCD’s Napa Youth Stewardship Council.

Visit the Napa RCD website for more information on the trap, to learn more about the RCD’s projects, and how you can get involved.