Why are steelhead counts sometimes higher at John Day Dam than The Dalles Dam even though it is further upstream?
The Army Corp of Engineers did a study to try and discover the root of the discrepancy. Their findings were summarized as being due to many factors including: errors in visual counting (as compared to video), problems with conversion rates (to extrapolate count to full hour), errors at the north counting stations at both dams, and large numbers of fall backs at John Day Dam (meaning the same fish is counted multiple times). For more detailed information you can view the report here.
Related Questions
- Are the adult counts for wild steelhead a subset of the adult steelhead counts? How are wild steelhead identified at the Corp of Engineers Dams?
- Why are steelhead counts sometimes higher at John Day Dam than The Dalles Dam even though it is further upstream?
- Why are the shad ladder counts higher at The Dalles Dam than Bonneville?
