Visitors to Cape Cod National Seashore during the coronavirus pandemic have been dumping garbage there/NPS

Editor's note: This updates with Guadalupe Mountains National Park, Sagamore Hill National Historic Site, and Saint Croix Island International Historic Site all closing Friday, and some seasonal openings at Acadia National Park pushed back.

While staff at Great Sand Dunes National Park and Preserve in Colorado prepared to close the park Friday night, Guadalupe Mountains National Park in Texas closed earlier in the day, and staff at Cape Cod National Seashore in Massachusetts was dealing with garbage and vandalism.

At Great Sand Dunes, staff planned to close the park at midnight. This closure includes all public access points, park roads, and backcountry access, a park release said.

"We have been monitoring conditions at the park and working closely with the local public health officials,” said Superintendent Pamela Rice. “Due to increasing visitation, we can no longer mitigate the risk of exposure to the novel coronavirus and agree that it is in the public’s best interest to close at this time.”

Guadalupe Mountains Superintendent Eric Brunnemann announced Friday afternoon that they would close at 6 p.m.

"We will continue to keep in close communication with state and local partners as we progress through this closure period, and look forward to resuming operations again in the future," he said.

At Cape Cod, staff discovered vandalism and dumping at seashore locations, and have observed numerous regulations not being followed.

Construction materials were dumped in the Doane Rock area in Eastham, and household trash was dumped at Great Island in Wellfleet, a park release said. Fencing was vandalized in Truro. In addition, there have been increased violations, including pets on trails, in shorebird areas, and off leash; and bicycles, dirt bikes, and ATVs on trails.

“This is a challenging time for everyone, including the national seashore,” said Superintendent Brian Carlstrom. “Following guidance from the administration, CDC public health guidance, and the governor’s orders, we are maintaining essential functions with a small staff at the seashore. We do not have the resources to address these careless acts. We will issue citations to those who do not follow regulations, and we may be forced to close areas of the seashore if violations continue.”

All public buildings in the seashore, including restrooms, are closed. Trash cans have been removed to reduce staff exposure to illness. The public is urged to follow the Massachusetts governor’s stay at home advisory.

“We understand how important it is for people to have the opportunity to get outdoors to relieve some of the stress that COVID-19 is causing,” said Carlstrom. “We urge the public to respect their seashore, follow all guidance and regulations, and act responsibly."

Sagamore Hill National Historic Site in New York also closed to the public Friday, as did Saint Croix Island International Historic Site in Maine.

"Visitors are coming to Sagamore Hill in increasing numbers that makes proper social distancing on our popular trails more and more difficult,” said acting Superintendent Jonathan Parker. “We are committed to continued close coordination with our state and local partners as we progress through this closure period and we’re encouraging our visitors to explore the high-quality virtual visit options on our website.”

In Maine, Acadia National Park announced it would delay the spring opening of its campgrounds until June 15, and that the Hulls Cove Visitor Center, normally set to open May 1, wouldn't open before June 1, and that the Sieur de Monts Visitor Center, normally set to open first Saturday in May, would be delayed at least until June 15.