Donald Trump tees off at his Trump National Golf Club in Sterling, Va. (Jeffrey MacMillan/for The Washington Post)

An environmental advocacy group said it is pushing for Republican presidential hopeful Donald Trump to donate 500 mature trees to a Northern Virginia parks program.

To expand and upgrade the 800-acre property that is part of the Trump National Golf Club in Sterling, an acre of roughly 465 trees along the Potomac River was cut down. At the time, officials with the Trump Organization said they spent about $1 million removing the trees, which included black locusts, green ashes and American elms. They said the trees were stressed and eroding the soil. Trump’s operation did not need approval from Loudoun County to cut down the trees, but it said it did tell officials of its work.

But a petition started by the Potomac Conservancy in Silver Spring wants the real estate mogul to donate trees to be planted in Loudoun County. The group said it sent its petition — with roughly 6,300 signatures — to the head of the golf course, asking that Trump’s operations donate trees to the local parks program by Dec. 11. The petition was sent Wednesday, giving Trump’s operations a month to make a donation. The conservancy wants the trees planted in Loudoun County to “mitigate the damage from the forest loss,” the group said in a statement.

Officials at the golf course did not return a phone call and e-mail seeking comment. The president of Potomac Conservancy, Hedrick Belin, said his group has not heard from the golf course about its petition.

The conservancy claims that cutting down the trees along the river banks threatens “local water quality, wildlife habitat and aesthetics.”

In a press release, the group called Trump’s removal of the trees a “clear-cutting disaster” and argued that it “threatens DC water quality to further develop a golf course for a wealthy few.”

Belin said a commitment from Trump’s operations to plant the trees would be an “opportunity for Trump to show he wants to be a good neighbor.”

In June at an unveiling of his $25 million renovated golf course, Trump said he didn’t buy the property to have a “little glimpse” of the river. He said the trees were massive and “you couldn’t see anything.” Cutting the trees, he said, gave “unobstructed views”of the river.

”You can go 20 miles up and down the river and there’s nothing like it,” Trump said at the time.

Trump bought the property, the former Lowes Island Club, in 2009 for $13 million. He also bought other properties around it and built a $10 million tennis center. The club said it has about 1,000 members. The golf course is expected to host the 2017 Senior PGA Championship.

In the environmental group’s release, Belin said that “trees are nature’s Brita filter and one of the most cost-effective ways to maintain the purity of local water quality.

“Trump’s irresponsible actions to cut down trees and destroy water quality for the sake of a golf course show how out of touch he is with the way we do business in Washington, DC.”

The group also quoted Robert Snowhite, a fly fishing guide in Alexandria, as saying the trees helped keep some of the sediment out of the area, “but now all we have are his Trump Stumps and a polluted river.”

DCist was among the first to report on the petition calling for Trump to replace the trees along the river.

Trump isn’t the only rich man who has drawn scrutiny by cutting down trees in the D.C. region.

Washington Redskins owner Daniel M. Snyder had access to top officials at the U.S. Park Service when they helped broker a deal for him to cut down more than 130 trees on a hillside between his Potomac estate and the C&O Canal.