Slide 22 of 33
Notes:
- In looking at the flows at McNary Dam, we observe the impacts of actions on both the Snake and Columbia rivers. About 22 percent of the time, flows are likely to be lower in the “no new resource” scenario at McNary in the first half of August, 2003. (About 22 percent of the time, the red dashed line is below the solid black line).
- In years when flows are lower, they average about 6,000 cubic feet per second lower. In the worst case, the flow is nearly 13,000 cubic feet per second lower. (The biological opinion flow target at McNary for this period is 200,000 cubic feet per second).
- Although this result is not good for migrating salmon, it is not as bad as it could be. Converting the 6,000 cubic feet per second average shortfall into volume yields about 200,000 acre-feet. This volume is much less than the average shortfall of flow augmentation water in April, which was about 1.1 million acre-feet.
- So where did the extra water come from? The answer is from reservoirs drafting below the biological opinion flow augmentation limits to meet power needs. The last chart on the next page illustrates what is going on.
