The National Park Service said Tuesday the work at Sprague Lake Dam will be done in the fall of 2017, and parts of the trail around the lake will be closed.
The half-mile trail is wheelchair-accessible and affords sweeping mountain views. The lake is popular with anglers and picnickers and is open year-round.
Repair work will include improvements to the spillway, raising the dam slightly in some areas and reinforcing the lake side of the dam to prevent erosion.
The park had 4.1 million visitors last year and is on pace to exceed that this year. The park does not track visitor numbers to Sprague Lake.