Water resources development projects such as reservoirs or stream channel modifications, whether existing or only potentially planned, must be considered when selecting a stream crossing location. Planned resources development projects often require the relocation or reconstruction of existing highways and can interfere with the location or design of proposed highway-stream crossings. Many water resources development projects are planned or authorized for periods of years or even decades before construction begins. Others never come to fruition or may be permanently stopped by court decisions or regulatory agency actions.The roadway designer must carefully plan and construct a highway facility near a water resources project location, designing the highway facility for both existing and future site conditions. The excess cost of building the facility due to the water resources project must be considered in selecting the stream-crossing site. See Chapter 12, .