A group makes its way back to Seneca Creek under the canal aqueduct after spending time on the Potomac River on Sunday. (Toni L. Sandys/The Washington Post)

The ranking Democrat on the House Transportation Committee sent a letter Wednesday asking the commandant of the Coast Guard to reverse the agency’s new policy of kicking boaters off the Potomac River when the president or senior administration officials visit Trump National Golf Club.

Rep. Peter A. DeFazio (D-Ore.), in the letter to Adm. Paul F. Zukunft, said the security zone newly established by the Coast Guard along roughly two miles of the Potomac that borders the golf course is unfair to those who use the river.

“Time and again President Trump, with the aid of the Secret Service, has disregarded the needs of the general public for his own personal benefit and convenience,” DeFazio wrote in the letter, which was co-signed by Rep. John Garamendi (D-Calif.), the ranking Democrat on the House Transportation subcommittee on Coast Guard and maritime transportation.

“We implore you not to allow the President’s frequent leisure activities to take away access to the river,” the letter said.

Zukunft is scheduled to testify next week before the committee on an unrelated topic. Jen Gilbreath Adler, the Democratic spokeswoman for the committee, said he would probably be questioned about the river closure as well.

White House spokeswoman Lindsay Walters referred questions about the security zone and the Democrats’ letter to the Secret Service, which referred questions to the Coast Guard. A Coast Guard spokeswoman said the commandant typically responds directly to letters from lawmakers, in writing or in testimony.

The Washington Post reported Monday that the Coast Guard has adopted a new regulation that permits it to cut off river access when the president or other “high-ranking” government officials are at Trump National, which sits on the Virginia shore of the Potomac about 30 miles north of Washington.

The new policy — which will not be finalized until after Aug. 9, the deadline for public comments to the Coast Guard — has angered many who use that section of the Potomac. Among them are an Olympic athlete training for the 2020 Games, the Calleva summer camp, and Team River Runner, a kayaking program for wounded and disabled veterans.

“It’s really impolite for him to basically inconvenience all these people so he can play on one of his own courses,” DeFazio said in an interview Wednesday.

The Coast Guard has defended the new security zone, saying it comes at the behest of the Secret Service and will establish clear boundaries for river access when the president is at his golf course.

But questions remain about how the restrictions will be implemented. The policy calls for notification by marine radio, an option that paddlers say would be impractical. Coast Guard officials say news releases and online notifications may also be used to warn the public of the river closures.

In their letter, DeFazio and Garamendi ask who would qualify as a “high-ranking” government official and seek for the names and positions of those whose presence would require boaters to be kicked off the water.

They also ask whether concerns about the president’s security could be allayed by replanting trees along the banks of the river at the golf course.

Trump had the trees removed in 2010, prompting protests from environmentalists and paddlers.

DeFazio and Garamendi wrote that in retrospect the tree-chopping was “ironic,” because the now-cleared foliage “would have obscured the line of sight and mitigated security concerns.”