STRAFFORD — The grounds and buildings at the Justin Morrill Homestead will remain closed until the State Division for Historic Preservation can fully assess damage caused by last month’s flooding.

At issue is an unnamed stream, a tributary of the Ompompanoosuc River, that runs through the state historic site and national landmark. It runs along the property’s driveway off Justin Morrill Highway and to the north. The flooding was contained underground and there was no visible flooding aboveground.

“You can’t tell, which makes it all the more dangerous,” said Laura Trieschmann, state historic preservation officer.

The stream caused flooding in the basement of the site’s education center, she said. The stream’s bank is unstable — an issue that only made itself known in the weeks after the flooding. As of Monday afternoon, water continued to intermittently flood the basement at the education center.

“It was not visual flooding,” Trieschmann said. “It wasn’t until we started poking around with broom handles, trying to find a drain, that we realized the bank was compromised.”

State officials are concerned that the streambank could collapse and cause further damage. They are also worried about the potential for sinkholes: Justin Morrill created underground channels and culverts throughout his 6.19-acre property, which may have been impacted by flood.

Those culverts extend to under the site’s gardens, which are normally open to the public even when the buildings are closed.

“We just don’t know all the impact yet, the sources,” Trieschmann said. “We don’t know how unsafe it is at this point. I just really worry about people walking too close the stream.”

The floodwaters destroyed everything in the basement, including archival material stored there by the Strafford Historical Society. John Dumville, of Royalton, a member of the historical society’s board, told the White River Valley Herald that photographs and books were among the items lost.

Friends of Morrill Homestead, which runs programs at Justin Morrill, lost items it uses for events including a refrigerator, signage and “things that can be replaceable,” said Tracey McFadden, director of the nonprofit organization. The group also has had to cancel events at the site until further notice.

State officials were onsite from July 18 onward to assist with clean up, but it wasn’t until July 21 that they realized there could be more damage to the site than the flooded education center, Trieschmann said.

The site will be closed until representatives from the state Agency of Natural Resources can do an assessment.

Trieschmann said she is unsure when that will be, as the agency works to respond to other damage caused by flooding.

To some extent, the flooding caught the historic site staff off guard: When they checked the property on July 13, there was not any visible damage.

The education center is the newest building at the historic site: It was built in 2007 and got through Tropical Storm Irene in 2011 unscathed, Trieschmann said.

“It was a complete surprise,” she said.

The state owns the buildings at the homestead and has insurance, Trieschmann said. Any repairs will be the responsibility of the state and not the Friends of Morrill Homestead.

When the flooding came through McFadden was initially more concerned about the site’s historic buildings including Morrill’s 1851 Gothic Revival Mansion and the Carriage Barn, where art on loan from area artists was still hanging as part of an exhibition.

Fortunately, the art and the barn were largely untouched. The mansion’s basement had some water in it, but was spared significant damage.

“The basement was definitely wet and all the stones were dark so you knew it had definitely taken water, but the sump pump and the dehumidifiers were working,” Trieschmann said.

McFadden and the Friends’ board of directors are trying to move previously scheduled events elsewhere. Julius Jefferson, a section head of the Congressional Research Service at the Library of Congress, was scheduled to give a talk titled “The Morrill Acts and HBCU’s: Libraries and Literacy” at the homestead on Sunday, Aug. 13. Jefferson’s talk will now take place at 4 p.m. at the Strafford Townhouse and will also be available online.

Other events, including a printmaking class and a basket weaving workshop, have been canceled. McFadden is hopeful that the nonprofit’s biggest event, the annual 19th Century Apple & Cheese Harvest Festival will go on as planned Sept. 24.

“The Apple Fest is definitely our largest community event, where people come from all over for that,” McFadden said, noting that in the past it has drawn around 400 attendees. “For me it feels a little bit like COVID: We’re just waiting for answers about what we can and can’t do.”

McFadden said it is too soon to say what kind of financial assistance the Friends of Morrill Homestead will need: She found out Monday that they do not qualify for FEMA assistance for their lost supplies. Once the site reopens, there will be a need for volunteers, especially in the gardens.

“When they finally can, there will be lots of opportunities for volunteers to help because I’m sure the weeds will be flourishing,” McFadden said.

Updates on the homestead will be posted to morrillhomestead.org and Facebook: “Justin Smith Morrill Homestead.” Liz Sauchelli can be reached at esauchelli@vnews.com or 603-727-3221.