Current Predictions: 20 October 2021
Notes on the Predictions
Peak Arrival & Run Size predictions for spring Chinook at Bonneville Dam started in 2008. These predictions begin with a preseason prediction of run timing from a Genetics and Environment Timing model1 and a preseason run-size prediction. The daily, inseason methods to simultaneously estimate distribution parameters from the observations-to-date include use of up-to-date environmental conditions, historical bounds on parameters, and the mathematical properties of the gaussian distribution. The complete run of Chinook in the Columbia River is the sum of three sub-runs—spring, summer and fall—each well characterized by a gaussian distribution. For more information, please refer to Run timing of adult Chinook salmon passing Bonneville dam on the Columbia River.
Since 2005, the Daily Run Size & Passage Prediction (Date-based) is for the period March 15 - June 15 to best match the Columbia River Fisheries (CRM) spring management period. We use NOAA preseason forecasts generated for us. For information on the preseason forecasts and methods, please refer to Inseason Forecasts Methods and Information.
Starting with the 2005 migration season, the Passage Predictions are available for four stocks: Snake River, Upper Columbia River, Lower Columbia River, and Hanford Reach/Yakima. Percent of the run arriving at Bonneville Dam is based on historic run timing and observed visual count data (courtesy of U.S. Army Corps of Engineers, NWD). Stock separation of the run at Bonneville is based on stock composition, reach conversion rates, and run-timing of selected PIT-tagged stocks for all available years of adult detections at PIT Tag observation sites. Arrivals to the upstream dams are forecast with the Adult Upstream R Model.
- Snake River: Predicted percent passage through the projects on the Columbia mainstem and the lower Snake River. Locations: Bonneville, The Dalles, John Day, McNary, Ice Harbor, Lower Monumental, Little Goose, and Lower Granite.
- Upper Columbia River: Predicted percent passage through the projects on the Columbia River with destination above Priest Rapids Dam. Locations: Bonneville, The Dalles, John Day, McNary, Priest Rapids, Wanapum, Rock Island, Rocky Reach, Wells.
- Lower Columbia River: Predicted percent passage through the projects on the Lower Columbia River with destination above Bonneville but not above McNary Dam. Locations: Bonneville, The Dalles, John Day.
- Hanford Reach/Yakima: Predicted percent passage through the projects on the Columbia River with destination above McNary Dam but not above Priest Rapids Dam, these include Yakima and Hanford Reach stocks. Locations: Bonneville, The Dalles, John Day, McNary.
1. Anderson and Beer. 2009. Oceanic, riverine, and genetic influences on spring Chinook salmon migration timing. Ecological Applications. 19(8):1989-2003.