The photo above was taken a few weeks ago and shows what the Dowley Gap Aqueduct normally looks like. About a mile west of Saltaire, it carries the Leeds-Liverpool Canal at a height of 9m (30ft) over the River Aire. Also known as the Seven Arches Aqueduct, it was designed by the famous engineer James Brindley and constructed in 1773 by John Longbotham, who also designed the Bingley Five Rise Locks. (The canal predates the construction of Saltaire and its existence was one of the reasons Sir Titus Salt chose the area to build Salts Mill). It's hard to get a good view of the aqueduct at ground level. There are some more photos and a video here, with some aerial views that give a better idea of what the whole structure is like.
The drained aqueduct shows part of the original retaining wall, though the towpath on the left and the inside of the aqueduct have been covered in concrete at some point in its history. It is surprisingly shallow - canal boats don't have a very deep hull.
Your intrepid reporter managed to sink right up to her knee in the mud and I required the assistance of several hunky men in high-vis vests to haul me out. Haha! Luckily I had my wellies on (and they are a tight fit so the boot didn't pull off) and no harm was done.