BOISE, Idaho (AP) — Federal authorities are looking at returning Snake River fall chinook salmon above the Hells Canyon Complex of dams as part of a plan to eventually lift Endangered Species Act protections.

That's one option in the National Oceanic and Atmospheric Administration's 326-page recovery plan released Monday. Two other proposed plans involve ways to bolster the existing population below the Hells Canyon Complex. The building of the dams in the late 1950s and 1960s cut off 367 river miles to salmon, some 80 percent of historical spawning habitat.

Researchers estimate 500,000 salmon returned in the late 1800s but that fell to 350 in the early 1990s when the salmon were listed as threatened. About 50,000 have returned annually in recent years. Public comments on the plans are being taken through Jan. 4.