Expenses incurred by the Engineer Department of the Department of the Army in all investigations, inspections, hearings, reports, service of notice, or other action incidental to examination of plans or sites of bridges or other structures built or proposed to be built in or over navigable waters, or to examinations into alleged violations of laws for the protection and preservation of navigable waters, or to the establishment or marking of harbor lines, shall be payable from any funds which may be available for the improvement, maintenance, operation, or care of the waterways or harbors affected, or if such funds are not available in sums judged by the Chief of Engineers to be adequate, then from any funds available for examinations, surveys, and contingencies of rivers and harbors.