The large chamber at the Ballard Locks has been closed since Oct. 12 for the first of four scheduled extended closures to begin replacing the chamber’s filling culvert valves.

The 102-year-old valves, used for flooding and draining the large locks, are the same kind used for the construction of the Panama Canal. The valves are called Stoney gate valves, originally invented in the 1800s by Irish engineer Bindon B. Stoney.

The large lock will remain closed for up to 53 days, with a scheduled reopening Dec. 3. That’s a month longer than the typical November annual maintenance closure of two to three weeks.

The small chamber will remain open during this time and vessels up to 28 feet wide by 123 feet long are able to use it.