Construction of a new spillway was interrupted on Wednesday when workers discovered a leak in a temporary dam that keeps the construction site dry.
The size of the leak was compared to what a garden hose might spew.
"It's pretty slow moving, but you can definitely see it...it's not something coming through and you can't get a visual on it," said Kristine Des Champs, Army Corps of Engineer project manager.
The 65-foot-high coffer dam holds back around 20 to 30 feet of reservoir water from the construction site on the water side of the new spillway. It's not known if the rising lake level due to recent storms put more pressure on the structure.
About two dozen construction workers with the Army Corps of Engineers chief contractor were evacuated as a precaution.
Work on other parts of the project was also shut down.
Construction equipment was high and dry while loads of rock and dirt were brought in to stop the seepage. But they were in danger of being swamped and contaminating the water with oil or gasoline.
By the afternoon, the leak was halted and construction equipment was being removed from the site.
"To us, it's not that large a deal ... we have it handled, we are working through the process and procedures," said Army Corps Project Manager Kati Charan.
The corps says it will determine how to proceed because the coffer dam was scheduled to be removed in the next several weeks. It's a possibility that it could be removed early because excavation work could be done underwater.
The project is scheduled to be completed in the fall 2017.