When a proposed reservoir is expected to impound floodwater on an existing highway location, ust the highway should be adjusted to meet the same conditions of structure size, embankment elevation, and protection that apply to new locations. The roadway should also be upgraded to meet current geometric design standards. All adjustments to the highway are usually the responsibility of the reservoir sponsor, as stated in the Texas Administrative Code 43 TAC 15.54(f). "Department" in this context refers specifically to TxDOT.

"(f) Highway adjustments for reservoir construction.

"(1) Where existing highways and roads provide a satisfactory traffic facility in the opinion of the department and no immediate rehabilitation or reconstruction is contemplated, it shall be the responsibility of the reservoir agency, at its expense, to replace the existing road facility disturbed by reservoir construction in accordance with the design standards of the department, based upon the road classification and traffic needs.

"(2) Where no highway or road facility is in existence but where a route has been designated for construction across a proposed reservoir area, the department will bear the cost of constructing a satisfactory facility across the proposed reservoir, on a line and grade for normal conditions of topography and stream flow, and any additional expense as may be necessary to construct the highway or road facility to line and grade to comply with the requirements of the proposed reservoir shall be borne by the reservoir agency."

Reservoirs that fall into this category are usually major facilities. The reservoir designs are usually well documented and available for the hydraulic designer's use in the analysis.