The National Culvert Removal, Replacement, and Restoration Grant Program (Culvert Aquatic Organism Passage (AOP) Program) is an annual competitive grant program that awards grants to eligible entities for projects for the replacement, removal, and repair of culverts or weirs that meaningfully improve or restore fish passage for anadromous fish.

Eligible Project grant activities may include preliminary and detailed design activities and associated environmental studies; predevelopment/preconstruction; preliminary engineering; acquisition of rights-of-way; consultation and permitting activities; the National Environmental Policy Act (NEPA) process; the replacement, removal, or repair of culverts or weirs, or weir improvements; and the replacement of an eligible facility with a new facility that meaningfully restores fish passage.