Jewell, who previously served as chief executive for outdoors outfitter REI, acknowledged that meals had not been a highlight of her visits to national parks.
"Let's just say I packed my own food," she said.
The new era in park service food was on display at last week's event, as chefs from major concessionaires dispensed free samples of menu items, including bison tenderloin, black bean sliders, sweet potato cakes, chilled strawberry rhubarb gazpacho and summer fruit spritzers.
The cuisine received almost universally positive reviews from samplers, including tourists who stumbled on the event, federal workers on lunch breaks, visiting schoolchildren from Louisiana and a small pack of pedicab drivers delighted with the free food and drink.
"Refreshing and decadent," Jennifer Schoenborn of Reston, Va., declared after tasting a berry yogurt parfait with cinnamon crisp.
The healthy food standards will be integrated into all new concessions contracts and applied on a voluntary basis to existing contracts. Existing contracts will be replaced as they expire with new ones incorporating the standards.
Gerry Gabrys, chief executive of Guest Services Inc., a major park concessionaire, said the companies have seen a growing public demand for healthy food. "Without exception, the national park concessionaires are excited and wholeheartedly support the initiative," he said.
Park officials want to avoid comparisons to New York Mayor Michael R. Bloomberg's ill-fated attempt to ban the sale of super-size sodas in the city.
"We're not doing that," Jarvis said. "But there will be a non-sugary beverage available. If you want a sugary drink, you can drink as much sugary drink as you like."
The standards dictate that at least 30 percent of drinks offered have no added sugar and that low-fat and fat-free milk be available.
The local- and sustainable-food guidelines will depend on availability and cost. "I can't dictate locally grown if nothing is locally grown," Jarvis said. "In the middle of Idaho, I can certainly do potatoes, but maybe not arugula."
Some park concessionaires are already working with local farmers and vendors to prepare items such as Mount Rushmore's "Lakota popcorn," from the harvest of the Lower Brule Sioux tribe.
The healthy food standards do not apply to concessionaires operating in the backcountry, such as outfitters running multi-day raft trips through the Grand Canyon, where food has to be carried as compactly as possible.
Nor does the service dare mess with calorie-laden but popular traditional fare. The popovers at Acadia's Jordan Pond House and the "caldera" chocolate cake at Old Faithful Inn in Yellowstone will remain on the menu.