Nice pictures, although I can't seem to see the right hand side of them.
In the bottom photo, I am stood on the top of the cage.
Levels are often reckoned in fathoms below adit. Bear in mind that the adit has a gradient to make water flow, it will generally be referred to, for instance in Dines as "So and So shaft, adit at X fathoms". So, a 20F level is below adit, which will be so and so from surface. The only way is to clear the crap out of the way, or look at a detailed plan.
I have a feeling there is information on the levels, either on this site, or Mine Explorer.