The Little Falls Lake dam project at Willow River State Park was likely delayed several weeks after floodwaters breached a temporary dam securing the construction site.

State Park Manager Aaron Mason said the breach occurred Sunday, March 24. Time-lapse photography from the project’s website shows water breaching the site around 2 p.m. Sunday and quickly filling it over the course of the following hour.

“We certainly had an incident that had some flooding and damage,” Mason said.

The incident washed away construction materials and a small boat that crews were using to access parts of the dam project. Mason said the extent of damage and lost materials was unclear Tuesday, with the site still underwater.

He said engineers and architects did not think the main structure under construction was damaged, but that would also be confirmed once the waters recede.

“It’s certainly a setback that’s quite unfortunate,” Mason said, calling it “unexpected and unfortunate that it had to happen at this point in time.”

He said it’s not exactly clear what caused the breach. It was likely a combination of high water through a restricted flow, logs, saturated soil and ice chunks, Mason said.

He said the main task once waters recede will be rebuilding the construction site and cleaning up debris that floated away. Most of the construction materials were contained to the area between the dam and Trout Brook Road, Mason said.

He didn’t have a cost estimate from the incident, but said he doubts it will put the $20 million project over budget.

The project was scheduled to be finished in September. Mason said the flood incident will likely push completion out to October.

He added that park and construction crew officials continue to stress safety issues surrounding the project site. Mason said people need to stay away from the site for safety reasons including debris, saturated soil and construction activity.