 As originally built, the lock had timber sides up to normal head water level, and turf above that.The crest of the weir was above low water level at Teddington, but following the removal of the piers of old London Bridge (demolished 1831) in 1832, the drop increased to and increased to when dredging of the river was carried out.At tidally lower water occasional grounding of barges took place below the bottom sill.