A claim of actual water savings elsewhere to offset water taken from a river under the Act must be established with reasonable certainty. An effect is reasonably certain if it is established by clear and substantial information, rather than speculation and conjecture. Reserving certain lands is insufficient absent proof that those lands would otherwise be used for agriculture.
Scientific proof that the species is an opportunistic forager provides sufficient evidence for the determination that its members are likely to migrate after the reduction in water levels. The distance a snake might travel away from a river is fundamentally different than the distance that a snake might travel along a river. Agency's determination of minimal impact to species not arbitrary and capricious.
CONCURRENCE:
As the agency's determination doesn't meet the simple criterion of "likely," the standard of "reasonable certainty" is dicta.
Center for Biological Diversity, et al. v. Deb Haaland et al.