For purposes of laws relating to navigation on inland and intracoastal waterways of the United States, the term “rehabilitation” means—
(1) major project feature restoration—
which consists of structural work on an inland navigation facility operated and maintained by the Corps of Engineers;
(2) structural modification of a major project component (not exhibiting reliability problems)—
which will enhance the operational efficiency of such component or any other major component of the project by increasing benefits beyond the original project design; and
Such term does not include routine or deferred maintenance. The dollar amounts referred to in paragraphs (1) and (2) shall be adjusted annually according to the economic assumption published each year as guidance in the Annual Program and Budget Request for Civil Works Activities of the Corps of Engineers.