To require full spending of the Harbor Maintenance Trust Fund, to provide for expanded uses of the Fund, and to prevent cargo diversion, and for other purposes.

Harbor Maintenance Trust Fund Reform Act of 2017 This bill amends the Internal Revenue Code to make certain amounts in the Harbor Maintenance Trust Fund available, without appropriation, to pay 100% of the eligible operations and maintenance costs of specified portions of the Saint Lawrence Seaway (a system of locks, canals, and channels in Canada and the United States that permits oceangoing vessels to travel from the Atlantic Ocean to the Great Lakes) as well as those assigned to commercial navigation of all U.S. harbors and inland harbors; rebates of certain tolls or charges on the seaway; and all expenses of administration relating to harbor maintenance tax incurred by the Department of the Treasury, the U.S. Army Corps of Engineers, and the Department of Commerce. The bill also amends the Water Resources Development Act of 1986 to require allocation to certain donor ports and energy transfer ports of at least 20% of amounts made available each fiscal year from the trust fund, and the Department of the Army to make allocations equally between these types of ports.