Gateway communities such as Jackson could suffer significant economic impact as families alter summer vacation plans because of a budget impasse, National Park Service Director Jon Jarvis warned in a memo to agency employees.

The letter to all park employees, dated Tuesday, was the clearest outline to date of the agency’s view of effects to parks and neighboring towns. Press conferences, other leaked memos and interpretations of agency statements in recent days have sometimes been in conflict or caused confusion.

In Jarvis’ memo, he lamented the state of the political struggle as he reviewed the “grim reality” of the looming crisis. If Congress and the White House haven’t come to an agreement over “sequestration” by today, the Park Service will lose 5 percent — $134 million — of the money it expected to get.

An impasse “will have long-term and wide-ranging effects,” Jarvis wrote.

“Reduced services and access will make families planning summer vacations think twice about coming to a national park.

“A drop in visitation could have devastating effects on the economies of gateway communities who depend on visitor spending and shut down park lodging, food, and other services provided by concessionaires who support 25,000 jobs,” the memo states.

Wyoming’s congressional delegation has dismissed Park Service statements as grandstanding. Business owners in Jackson also are asking that visitors understand parks will be open this summer.

“They are blowing this way out of proportion!” a wildlife tour company posted on the Jackson Hole News&Guide Facebook page in response to a news bulletin about the memo. “Please share with everyone that Jackson, Grand Teton and Yellowstone will all be open for business this summer. Our livelihoods are being ... hijacked by being used [as] a pawn in their game.”

But the risks to the parks are real, Jarvis warned. Sequestration will result in a loss of seasonal employees.

“Seasonal employees will be furloughed, have delayed starts, shortened employment periods, or will not be hired at all,” Jarvis wrote. “We lose our utility infielders.

“Our seasonal workforce is the ‘bench’ we turn to when fires break out, search and rescue operations are underway, and every other collateral duty in the world needs doing,” the memo said. “Many of these folks return year after year; they are the repositories of amazing institutional knowledge for the park … and our visitors.”

The mandatory budget cuts will hit just as parks are hiring seasonal employees for the summer, Jarvis said.

“In some parks, like Yellowstone, the impact has already started; those who would normally be getting ready to plow roads for the spring season are on hold and the opening of the park could be delayed up to a month,” the memo said.

At Grand Teton National Park, spokeswoman Jackie Skaggs said new information about cuts in the parks is expected today or Monday. She said part of Jarvis’ memo that contemplated furloughs for permant staff was off-base.

“There was some confusion between the Department of Interior and National Park Service,” she said. “The NPS has determined that permanent staff will not be furloughed.”

However, the budget crisis will extend to affect other programs parks have come to rely on, such as cooperative ventures involving students. The implications may be felt into the future, Jarvis said.

“Students are a vital part of our workforce today and integral to the [n]ational [p]ark workforce of tomorrow,” Jarvis wrote. “Sequestration will mean that we will be unable to meet our youth hiring goals.

“We also expect significant reductions to cooperative agreements with partners that fund youth work crews and are the foundation for our vision of a 21st Century Conservation Corps,” Jarvis wrote. “Our inability to hire students and enter into cooperative agreements will have lasting impacts as these young people are forced to find work elsewhere and ultimately may make different career choices.”

The cuts will come on top of austerity measures already imposed since Oct. 1, including not filling permanent positions, Jarvis said. The Park Service parent Department of the Interior imposed some of those.

“Secretary [of the Interior Ken] Salazar has implemented a department-wide hiring freeze as well as given direction to reduce overtime, travel, training, contracts, cooperative agreements, and grants and eliminate conference attendance,” Jarvis wrote. “I want to emphasize to you that keeping positions vacant is not a sustainable strategy; it cripples our ability to meet mission responsibilities — from providing education programs to kids, to coordinating wildlife research, to managing museum collections — and it increases the burden on remaining staff that take on additional critical work that cannot go undone.”

— Mike Koshmrl contributed to this story.