Who is authorized to allow power lines to cross a river?

The U.S. Army Corps of Engineers (USACE) is the correct answer because it is the federal agency primarily responsible for managing and regulating the nation's waterways, including rivers. Under the authority granted by the Rivers and Harbors Act, the USACE has jurisdiction over structures that may affect navigation and the overall integrity of the waterway. This includes permitting the installation of power lines that cross rivers, as such projects might impact navigation channels and the river's ecological balance.

The other options, while involved in various aspects of planning and permitting, do not hold the specific authority to grant permissions for power lines to cross waterways. For example, the Local Planning Department generally works within municipal rather than federal regulations, focusing on land use and zoning rather than national waterway management. The Federal Energy Regulatory Commission oversees the regulation of electric utilities but does not specifically handle permits for structures across bodies of water. The Coast Guard Commandant plays a role in ensuring navigational safety and security on waters but does not directly authorize the crossing of power lines across rivers. Thus, USACE is the appropriate authority for this matter.