With the U.S. National Park Service facing budget cuts, General Mills is earmarking at least $2.5 million in donations over the next three years and tying it to a promotional campaign for one of its most outdoorsy brands: Nature Valley granola bars.

Nature Valley will donate 10 cents for every six-count box of its oats and honey flavored granola bars sold between March 1 and May 15, up to $750,000. Depending on sales, Nature Valley could increase its support for the parks up to $3 million.

The company also has developed an ad campaign titled “Give Back” and will use social media to encourage people to volunteer, donate and visit the nation’s parks.

“One of the things that unites the people that we serve is their love of spending time in nature,” Angela Rassi, Nature Valley’s marketing director, said in a statement. “We feel like now more than ever the national parks need their supporters to step up and take a more active role in preserving them for generations to come.”

The Trump administration’s current budget proposal would cut $1.5 billion in funding to the National Park Service. To account for the gap, the park service plans to trim the number of free days this year to four — down from 10 last year and 16 the previous year.

The agency also proposes to more than double peak-season gate fees, from $30 to $70. Of the 417 properties, only 118 charge entry fees, which help pay for maintenance and upgrades across the system.

Over the past decade, Nature Valley has given more than $3 million to support the nation’s park system, including initiatives with National Park Conservation and the National Park Foundation (NFP), said General Mills spokesman Mike Siemienas.

The current initiative will be directed toward the Find Your Park campaign.

“Our parks are in desperate need of repairs to park trails and roadways and maintenance of invaluable historic structures,” Siemienas said in an e-mail. “We are actively working with the NPF to understand the best use of these dollars. The Find Your Park campaign is a natural place to support. However, as we continue to learn and understand the needs of the parks, we will be agile on how we support them.”