Ross Baker, a distinguished professor of political science at Rutgers University, said that while the senator’s personal interests at the lake might make the legislation appear “slightly unsavory,” it was unlikely to amount to a serious ethical violation in the Senate. Rather, he said, “the downside for him is more in terms of political embarrassment.”

“In a state that would be politically more competitive than Oklahoma, this could be trouble for Senator Inhofe,” he said. “But Senator Inhofe is a local institution.”

In statements, Mr. Inhofe and the Grand River Dam Authority said that the legislation would clear up confusion about who was in charge of flood control and empower one federal agency — the Army Corps of Engineers — to balance water flow in the region.

The legislation is pending, and Senate and House representatives plan to negotiate a final bill in the coming weeks.

Richard Glick, a member of the Federal Energy Regulatory Commission, cautioned that there was a reason the commission regulates about 1,700 hydroelectric dams across the country.

“If you take the umpire out of the baseball games and let the pitcher call the strikes and balls,” he said, “what do you think the pitcher is going to do?”

Mike Baker contributed reporting from Seattle, and Carl Hulse from Washington.