Nearly $38 million could flow into Bay watershed land protection efforts, mostly along Chesapeake rivers, under the budget proposed by President Obama in February.

If approved by Congress, it would be the largest federal investment to protect the region’s open spaces and historic sites in recent history.

Most of the funding — $33.3 million — would support a new “Rivers of the Chesapeake” initiative that targets the protection of large-scale landscapes along Bay tributaries. Another $4.5 million would help protect other tracts in the region, such as portions of Gettysburg National Military Park, Cedar Creek and Belle Grove National Historical Park and along the Appalachian National Scenic Trail.

But the Rivers of the Chesapeake was the big budget prize. The proposed funding was only a little more than half of what proponents had requested, but it is nonetheless expected to lead to greatly increased federal land protection funding in future years — something that is also mentioned in the president’s budget.

“Even though it is half of what we asked for, I am still thrilled,” said Joel Dunn, executive director of the Chesapeake Conservancy, which rallied support for the initiative. “This is a big deal. With this budget, we’ve made enormous progress. I think it reflects really well on all the partners involved.”

A coalition of federal agencies, state governors, Indian tribes and land conservation advocates had unsuccessfully pushed the initiative for three years before winning a place in the president’s 2016 budget proposal.

“The partnership that worked to include these funds in the president’s budget recognizes the enduring value of our great rivers and the Chesapeake Bay to the economy, our history and our environment,” said Virginia Gov. Terry McAuliffe, who met personally with senior administration officials to promote the project.

The initiative would help fund about 7,500 acres of land acquisition; mostly unprotected lands within the boundaries of existing areas targeted for protection, such as the Rappahannock Valley and Blackwater national wildlife refuges, as well as tracts along the Captain John Smith Chesapeake National Historic Trail and even parcels far upstream on Bay tributaries in George Washington National Forest.

Most of the properties are adjacent to lands already owned or protected through easements by the federal or state government or by land conservation groups. The initiative’s intent is to leverage land preservation by others to protect large-scale landscapes for wildlife habitat and scenic vistas as well as water quality.

“Collectively, it is supposed to add up to a bigger impact: a migratory pathway for wildlife, an adaptation corridor for sea level rise, or a viewshed protected for the John Smith water trail,” Dunn said.

“The concept is that these ecosystems, and the wildlife within them and the services they provide, are operating at much larger scales than we’ve ever really collectively contemplated. Postage stamp-size parks aren’t going to save our wildlife, they are not going to cure our water quality issues, they are not going to protect our tourism resource values. They are good by themselves, but what we need to do is work together and link up numerous postage stamp parks in these corridors to preserve ecosystem functions and all of the values that they provide.”

How much of that vision for the Rivers of the Chesapeake becomes a reality hinges on the level of support provided by Congress.

The money would come from the federal Land and Water Conservation Fund, which is financed with royalties from oil drilling on the outer continental shelf. Created in 1964, the fund is authorized to spend up to $900 million a year for federal land protection and grants to support state and local parks, but Congress has rarely fully funded it, opting to use the money for other purposes. Funding levels in recent years have been around $300 million, with cooperative efforts to protect large-scale landscapes given priority.

If the LWCF is not fully funded, about $10 million of the Bay watershed funding falls into a high priority category established by the Department of Interior; the rest would be more vulnerable to cuts. Advocates said the region’s Congressional delegation could be instrumental in supporting funds for additional acquisitions, as long as they are identified within the administration’s budget proposal.

The initiative has strong support from members of Congress representing different portions of the watershed. Seventeen Representatives and nine Senators signed letters of support for the initiative.

“Protecting the watershed’s forests and wetlands is imperative if we are to have bountiful recreational opportunities, clean water and healthy lands for future generations,” said Sen. Ben Cardin, D-MD, one of the backers. “This makes the open space protection and landscape conservation measures included in the Rivers of the Chesapeake initiative tremendously important.”

Ann Swanson, executive director of the Chesapeake Bay Commission, an advisory panel that represents state legislatures and had been a strong supporter of the initiative, said the region would help bolster its case for continued federal support if states and nonprofits show they are supporting the initiative with additional funding.

“It is something to be celebrated. It is an extraordinary opportunity for an infusion of federal dollars that we haven’t had before. And the program will encourage strategic investments, and that is the way conservation should be done,” Swanson said. “The challenge now is to prove that the investment in the Chesapeake is a wise one.”

The initiative would also support a goal of the Chesapeake Bay Watershed Agreement signed last summer which calls for permanent protection for an additional 2 million acres of land, or 3,125 square miles, in the Bay’s 64,000-square-mile watershed by 2025.

If approved by Congress, the money for the Rivers of the Chesapeake initiative would support land acquisitions by the National Park Service, the U.S. Fish and Wildlife Service, the U.S. Forest Service, and the Bureau of Land Management.