This may include ensuring that hatchery releases do not interfere with each other. For example, if several hatcheries in the same river release their smolts at the same time, they may compete for food and habitat. Release times can also be optimized based on the abundance of estuarine predators. Hatcheries that wind up spreading strays all over the Basin might also need central regulation if they can't cure the problem in a reasonable time. So long as the single authority did not attempt to meddle with the details of hatchery operations, and just kept the pastures from being overgrazed, so to speak, everything would probably work out well.
State governments seem to have failed at managing the hatcheries.
There may not be a long-term enough perspective in state government. Personally, as part of a global and final settlement of Treaty rights, I would give the tribes a chance to manage the salmon resource by running most or all of the Columbia Basin hatcheries. New upriver hatcheries, like the Yakama and Umatilla Hatcheries can bring mitigation more in line with geographic demands. Right now, the tribes control only a fraction of the hatcheries. The United States Fish and Wildlife Service is actively resisting efforts by the Nez Perce Tribe to assume operational control of Kooskia National Fish Hatchery, which is located within the Reservation boundaries.