A Lock keeper, Lock Tender, or lock operator looks after a canal or river lock, operating it and if necessary maintaining it or organizing its maintenance. Traditionally, lock keepers live on-site, often in a small purpose-built cottage. A lock keeper may also be the operator for the lock's Weir, and in many cases lock keepers play an important role in moderating and controlling water levels in response to drought and heavy rain. With the decline in commercial traffic the occupation is dying out, at least in Britain. Many previously manned locks are now unmanned.
The Kentucky River Museum is located in a former lock operator's dwelling.
The Lehigh Coal & Navigation Company in 1900 paid their lockkeepers $18 USD per day, with a rent free house. They often had small stores to sell groceries to the passing boats, and also had to make minor repairs to the canal and locks.
On the Chesapeake and Ohio Canal the lockkeeper had a rent free house, an acre of land for a garden, and was paid a base of $150 a year. If he kept more than one lock, it was $50 for each extra lock, with a maximum of 3 locks.
Lockkeepers were on call 24 hours a day during the boating season.
On the Chesapeake and Ohio Canal, the lockkeepers were required to remove the windlasses from all lock paddles at night, to prevent unauthorized use. But they had to get up and man the lock if a boat came through at night.
Lockkeepers had to enforce company rules against the independent and wily boat captains. In some cases, they had to check waybills that the boats had. They also were responsible for the level (canal pound) by their lock, to fix leaks and other minor repairs.
Some lockkeepers simply left the job and disappeared. In June 1848, when Asa Aud had taken French leave, William Elgin the district superintendent, appointed John Boozell as tender of Lock 25 on the Chesapeake and Ohio Canal.
Often lockkeepers sold alcohol on the side, one notorious example being A. S. Adams of Lock 33 (Harpers Ferry) on the Chesapeake and Ohio Canal. At that site, the Salty Dog Tavern was known for its availability of liquor and easiness of women.
To help a boat get out of a lock (going downstream) the lockkeeper sometimes would give a swell, that is, opening the paddle valves (wickets) on the upstream gates, and the water would flush the boat out. Some wily lock keepers would demand money from the boatmen for this "service". If a boat ran aground between locks, they would sometimes ask a passing boat (going upstream) to tell the next lockkeeper to give an extra heavy swell, by opening all the wickets on the upstream lock thus raising the water level temporarily, so that they could get unstuck.