An independent investigation has determined that recent damage to a geotube system meant to curb erosion along one of Nantucket’s most vulnerable shorelines was an act of vandalism, and a $10,000 reward is being offered for information leading to an arrest, a local nonprofit said.
The Sconset Beach Preservation Fund said Ed Davis, Boston’s former police commissioner, had reviewed photos, video, and “material assessments of the damaged coastal protection system” and concluded the cuts to the containers were intentional.
“The clean, linear cuts are consistent with a premeditated and willful act of vandalism,” Davis said in a statement Monday. “This was in no way an accident or the result of natural forces.”
The roughly 950-foot geotube installation is below Baxter Road along Sconset Bluff on the island’s eastern shore and is designed to absorb wave energy, stabilize the bluff, and slow erosion along the shore, the preservation fund said.
In an interview, Davis said it’s unclear when the damage was made and whether it was done by one or multiple people.
“It would have taken a heavy knife to cut into this material,” he said.
He said the investigation is ongoing and the Nantucket Police Department is accepting tips. Anyone with information is asked to call the department at 508-228-3626.
“It’s a straightforward case of vandalism, but the damage could be in the millions of dollars if that section washes out,” Davis said.
Nantucket officials said police detectives are also investigating the damage.
“Patrol officers are aware of the incident and will remain alert for any unusual activity in the area,” the town said in a statement Wednesday morning.
A Nantucket police report said officers were alerted to the alleged vandalism on Feb. 2. The report said the tubes had five cuts that vary in size, with the smallest being about 3 feet long.
“The damaged geotubes appear to be leaking sand out of them and there may be more cuts in the already deflated geotubes,” police wrote in the report.
An officer who went to the scene looked for cameras attached to the houses that overlook the bluff but did not find any, according to the report.
The officer also spoke with two construction crews that were working in the area and was told they hadn’t noticed anything suspicious. One crew told the officer that all of the houses in the direct area are unoccupied during the winter and said the area has “very little traffic this time of year,” according to the report.
The project was built more than a decade ago after a major storm resulted in the loss of about 30 feet of land.
The massive tubes, made of plastic fiber and filled with hardening sand slurry, are meant to serve as a shield against encroaching waters.
The project has faced pushback over the years. Critics have said that the tubes and trenches pose a threat to the island’s landscape, arguing that homeowners along the bluff are seeking to preserve their land at the expense of nearby beaches.
The system functions as an integrated structure, so damage to any single section can compromise the whole and create what the preservation fund described as a “dynamic and escalating condition in which the magnitude cannot yet be predicted.”
“This is not just damage to a private project, it is damage to critical coastal protection infrastructure that helps stabilize the bluff and public property,” Meridith Moldenhauer, a representative for the preservation fund, said in the statement. “We take this matter extremely seriously and will continue to work with the Nantucket Police Department as they continue their investigation.”
Moldenhauer said the group is assessing the damage and awaiting a contractor’s cost estimate for repairs.
Davis’s findings come less than a week after the project cleared a major hurdle in an ongoing state review.
On Wednesday, the preservation fund and town officials announced that the state Office of Energy and Environmental Affairs had determined no further environmental review is required for the next phase of the protection project.
The damage to the geotube was discovered after part of the system collapsed late last month. The preservation fund said it found cuts through the dense geotextile material.
The Nantucket Coastal Conservancy, a group that opposes the project, posted video on social media on Jan. 31 that showed a section of the geotube had collapsed. On Tuesday, the group said it remains opposed to the project but condemned the alleged vandalism.
“There is no place in our community for acts like this,” the group said.
In a statement Wednesday, the conservancy said the geotube system has been “virtually abandoned since January 2023,″ leaving the tubes exposed to sunlight and waves. The group said the public beach in the area has narrowed and steepened, and future expansion of the geotube system could run afoul of conditions set by the Nantucket Conservation Commission.
“The best way to protect geotubes from vandalism is to keep them covered with sand,” the group said. “We have repeatedly asked the Conservation Commission, the Select Board, and even the State, to please take steps to ensure that SBPF provides the requisite amount of mitigation sand to no avail.”
Nick Stoico can be reached at nick.stoico@globe.com.