A rainbow colors the sky over the Dorr Mountain summit. (Photo by Avery Howe/Friends of Acadia)

Acadia National Park Physical Science Technician Jake Van Gorder places a bag of stones at Marshall Brook to facilitate research on the stream’s invertebrates while logging data for the Acadia National Park Air/Water Quality Program. (Photo by Sam Mallon/Friends of Acadia)

Visitors learn about astronomy at the Night Sky Ranger Program held on Sand Beach. (Photo by Avery Howe/Friends of Acadia)

Vibrant hues speckle the sky above North and South Bubble and reflect in Jordan Pond, as seen at sunset from the Jordan Pond Path. (Photo by Sam Mallon/Friends of Acadia)

High tide waves drain over the rocky shoreline of Schoodic Point. (Photo by Lily LaRegina/Friends of Acadia)

Deja Manson, of San Diego, Calif., left, and Lillian Anderson, of Charlottesville, Va., try to complete a bingo sheet of questions about different women currently working in the park during the drop-in ranger-led program, Today’s Women in Acadia, outside the Sieur de Monts Nature Center in Acadia National Park. It was one of ten special programs held to celebrate Women’s Equality Day on August 26. During the program, visitors were able to mingle with and talk to women working throughout the park’s different divisions and partner organizations. (Photo by Lily LaRegina/Friends of Acadia)

Eric Michelena, interpretive ranger, discusses the legacies of historical figures such as George Dorr and Charles Eliot and their contributions to the founding of Acadia National Park during the “Whose Acadia? Navigating Narratives” ranger-led program at Compass Harbor. (Photo by Lily LaRegina/Friends of Acadia)

Low-hanging clouds and heavy fog cover Bald Porcupine as the sun rises, viewed from the summit of Cadillac Mountain. (Photo by Lily LaRegina/Friends of Acadia)

Emma Lanning, Acadia National Park Biological Science Technician, trims new growth from an ash tree they girdled and will later cut down to track the effects of emerald ash borer beetles near Sieur de Monts. (Photo by Ashley L. Conti/Friends of Acadia)

Acadia National Park Physical Science Technician Jake Van Gorder collects data for water quality monitoring for the monthly water quality check in Jordan Pond at the Jordan Pond buoy. (Photo by Sam Mallon/Friends of Acadia)

Acadia National Park Biological Science Technician (Wildlife) Morgan Ingalls holds an Eastern small-footed bat (Myotis leibii) before starting tests on the bat, such as measuring wingspan and checking for signs of white nose syndrome, as part of a bat monitoring program. (Photo by Sam Mallon/Friends of Acadia)

Mike and Tracy McDowell, of Millersburg, Ohio, look out over the west side of Mount Desert Island from the Beech Mountain fire tower. (Photo by Lily LaRegina/Friends of Acadia)

Water flows in small cascades along the A. Murray Young Path. (Photo by Lily LaRegina/Friends of Acadia)

Caitlin MacPherson, Friends of Acadia Summit Steward, and Dan Holbrook, Friends of Acadia Summit Steward, work to repair a Bates cairn on the North Ridge Trail of Cadillac Mountain. (Photo by Ashley L. Conti/Friends of Acadia)

Chiara Jeanfils, Friends of Acadia Lead Summit Steward, finds a Coca-Cola glass bottle from 2002 while searching for base stones to repair Bates cairns down the North Ridge Trail of Cadillac Mountain. (Photo by Ashley L. Conti/Friends of Acadia)

Metal rods used for trail stabilization are seen on the Valley Cove Trail. (Photo by Lily LaRegina/Friends of Acadia)

Mist hangs over the Great Meadow, viewed from the Emery Path on Dorr Mountain. (Photo by Lily LaRegina/Friends of Acadia)

Visitors hike on the Jesup Path. (Photo by Lily LaRegina/Friends of Acadia)

One of many orange jewelweed (Impatiens capensis) flowers seen along the Valley Cove Trail. (Photo by Sam Mallon/Friends of Acadia)

Crew members from Linkel Construction finish work on a new fish passage at Seal Cove Pond. The new passage replaces the fish ladder formerly connecting alewives and blueback herring from Seal Cove to the pond to spawn.(Photo by Lily LaRegina/Friends of Acadia)

An American lady butterfly rests off the North Ridge Trail of Cadillac Mountain. (Photo by Ashley L. Conti/Friends of Acadia)

Wambli Martinez, of Houlton, ME, works with the vegetation crew via the WAYS Trail Crew of Wabanaki Youth in Science, using a hand scope to identify hemlock wooly adelgid, an invasive pest threatening hemlock trees in the park, found along Jordan Stream Path. (Photo by Sam Mallon/Friends of Acadia)

Visitors at the summit of Cadillac Mountain wait for the sun to rise. (Photo by Lily LaRegina/Friends of Acadia)

Friends of Acadia Summit Stewards Dan Holbrook, left, and Chiara Jeanfils disassemble visitor-made rock piles on Bar Island in Acadia National Park. Rock stacking is a practice that may have several negative impacts in Acadia, including promoting soil erosion and impacting wildlife in intertidal zones. (Photo by Lily LaRegina/Friends of Acadia)