The state Department of Land and Natural Resources says it’s investigating after a beachfront property owner rented an excavator and moved large amounts of sand in front of his homes at Rocky Point on Oahu’s North Shore to protect them from erosion.

The brash move is the latest in a series of unauthorized activities that homeowners along the famous stretch of coastline have taken in recent years to try to protect their properties from being damaged or destroyed by the ocean at the expense of the public beach.

In February one of those homes collapsed onto the shoreline, underscoring the increasing precariousness of the situation for the occupants of the homes as well as the public.

Todd Dunphy, the property owner at 59-181-E and 59-181-F Ke Nui Road, did not return a Honolulu Star- Advertiser message seeking comment. But he told Hawaii News Now earlier this week that he had spent about $200,000 moving the sand. He also said he would rather take whatever fine might be forthcoming for his actions.

The two properties have a combined value of approximately $5 million, according to city property assessments.

DLNR, which can fine owners $15,000 a day for unpermitted activities along the shoreline, didn’t respond to questions about whether it was considering fining Dunphy. DLNR spokesperson Dan Dennison said the department does not comment on pending investigations. DLNR did tell Dunphy that he needed to put back the sand.

This isn’t the first time that Dunphy, a martial arts champion, has been warned by DLNR about alleged vio­lations. In February the agency sent Dunphy a letter saying that multiple state inspections in January and February showed ongoing installation of unauthorized erosion-control materials and debris on the public beach fronting his homes.

DLNR photos show large boulders, concrete pillars, sandbags and torn-up tarps littering the shoreline.

The letter to Dunphy said DLNR has “numerous concerns about these materials and work being done,” noting that shoreline structures can accelerate beach erosion on neighboring properties and harm the beach. However, the letter stopped short of saying that officials planned to take any enforcement action.

It’s not clear whether the material was ever removed.

Dunphy has been outspoken about his frustration that the department isn’t doing more to help private property owners, even getting into a public spat with DLNR Chair Suzanne Case in February as media swarmed to cover the collapse of the neighboring home.

“Can I save my house today and do what I have to do?” he demanded of Case.

“We need rocks. We need something now. That’s what we need, really. We are asking, we are begging, for the DLNR to give us some help.”

However, DLNR’s mission is to protect natural resources, including Hawaii’s beaches, which have been increasingly destroyed over the decades by shoreline hardening, a result of homes, roads and other infrastructure being built too close to the shoreline.

In recent months the department has taken a harder line against property owners, warning them that they need to come up with plans for their homes that are increasingly being threatened by erosion that’s only set to worsen amid accelerated sea level rise. Those options include moving their homes.

But homeowners have been uncooperative, refusing to remove large emergency sandbags and tarps, commonly referred to as burritos, long after their authorizations have expired. Those hardening structures are already causing erosion along the beach at Rocky Point, according to DLNR documents, in addition to blocking the public shoreline and posing a public-safety hazard.

The department hasn’t fined any of the property owners along the beach, though it continues to warn that the structures are not allowed.

“There are no current valid permits for emergency measures in this area, and numerous temporary emergency permits have expired or activities were conducted that weren’t authorized under the permits,” Dennison said in a statement. “DLNR continues to be focused on protecting the public trust in beaches. The homeowners in this area, whose homes are built on sand berms that are needed to replenish the beach area, may ultimately need to move their homes to other locations away from the eroding coastline.”