; $2,161,000,000, to remain available until expended; of which such sums as are necessary to cover the Federal share of construction costs for facilities under the Dredged Material Disposal Facilities program shall be derived from the Harbor Maintenance Trust Fund as authorized by Public Law 104–303 ; and of which such sums as are necessary to cover one-half of the costs of construction, replacement, rehabilitation, and expansion of inland waterways projects shall be derived from the Inland Waterways Trust Fund, except as otherwise specifically provided for in law. Mississippi river and tributaries For expenses necessary for flood damage reduction projects and related efforts in the Mississippi River alluvial valley below Cape Girardeau, Missouri, as authorized by law, $350,000,000, to remain available until expended, of which such sums as are necessary to cover the Federal share of eligible operation and maintenance costs for inland harbors shall be derived from the Harbor Maintenance Trust Fund. Operation and maintenance For expenses necessary for the operation, maintenance, and care of existing river and harbor, flood and storm damage reduction, aquatic ecosystem restoration, and related projects authorized by law; providing security for infrastructure owned or operated by the Corps, including administrative buildings and laboratories; maintaining harbor channels provided by a State, municipality, or other public agency that serve essential navigation needs of general commerce, where authorized by law; surveying and charting northern and northwestern lakes and connecting waters; clearing and straightening channels; and removing obstructions to navigation, $3,740,000,000, to remain available until expended, of which such sums as are necessary to cover the Federal share of eligible operation and maintenance costs for coastal harbors and channels, and for inland harbors shall be derived from the Harbor Maintenance Trust Fund