Predictions are estimated with the RealTime model using PIT tag data and Passage Index data. PIT tag data is courtesy of the Pacific States Marine Fisheries Commission . Passage Index data is courtesy of the Fish Passage Center .
Composites are the combined data of the streams they include, treated as a single stock.
These forecasts are based on detections of PIT-tagged wild subyearling fall chinook at Lower Granite Dam. Detections of these subyearling chinook at Lower Granite constitute a fairly good representation of the subyearling fall chinook run at large, particularly during the first and middle portions of the run. 4 Program RealTime predictions are based upon the historical outmigration pattern detected at a specific point, and its estimation accuracy therefore depends on regularity in these patterns. This is true of Rock Island Dam as well, where irregularities in the patterns of fish passage over Rock Island Dam occur largely due to hatchery releases upriver from the dam. These unpredictable events increase the variability of outmigration patterns from year to year, making accurate predictions more difficult and resulting in wider confidence intervals for the RealTime predictions.