In our last post we disclosed the reasons why we eliminated Alternative 1-1 from further consideration. Cost was a big factor, but the main reason is the lower probability involved with Alt 1-1’s ability to pass fish.
Passing fish is the primary purpose of this fish-passage project, so we must succeed in that effort. And success in this case requires a full-river width in-channel fish passage.
We understand higher water levels are important to the community. It’s worth pointing out that we did consider another alternative with a full-river width fish passage that holds water higher than the recommended plan. It is also much more affordable than Alt 1-1. This brief post is intended to use the below illustration to compare water levels between Alt 1-1, which is no longer considered, Alt 2-6a, the highest full-river width fish passage in our final alternatives, and Alt 2-6d, our recommended plan.
We didn’t recommend Alt 2-6a because our models indicated the higher weir height would occasionally cause nuisance flooding. The shallow inundation would occur on a number of parcels of farmland and some forested areas upstream of the lock and dam. There’s nothing that prohibits this kind of inundation, but the non-federal sponsor would be required to mitigate the impact. The mitigation would involve working with local officials to obtain any lands, easements, rights-of-way or relocations if necessary.
~Russell Wicke, Corporate Communications
