There is ongoing construction work fixing up the canal between locks 5 and 22. I was at Great Falls this weekend and saw what work is being done there. The entire project started last winter and will continue through next spring, however I don't know when the work around the tavern will be done. Even with the construction, the area is still open and usable, so don't let this keep you from going.
There is a structure here where water can be diverted from the canal back into the Potomac river, they have totally torn it out and are rebuilding it.
Looking south at the lock by Great Falls Tavern. The black plastic pipe carries the water in the canal past the construction.
Looking north, you can see the gravel dam at the top of the picture which the construction vehicles use to cross onto the tow path. Peyond that you can barly see the white of the dam that actually blocks the water and that visitors can use to cross back onto the tow path.
South of the construction zone, this is where you have to leave the tow path and cross over the bridge to continue north along the canal.
Unrelated to the construction, but important if you plan to visit in the next few days, the Billy Goat trail is closed because of high water. Olmstead Island is open and is a great place to see the river during high water.