but navigation of its southernmost tidal reaches of Bow Creek were difficult due to its tortuous meanders.

There is documentary evidence that the river was altered by the Abbot of Waltham to improve navigation in 1190, and in 1221, a pipe was laid across the river, which had to be protected from "the oars or poles of the watermen." The first act of Parliament for improvement of the river, the ' (3 Hen. 6.