Premise: Three Mills Wall River Weir is a weir on the Bow Back Rivers, in the London Borough of Newham, England, near to Three Mills. It was built in 2009, when the Bow Back Rivers were refurbished to make them a key feature of the Olympic Park, London, and maintains water levels through much of the park in conjunction with the Three Mills Lock and sluice on the Prescott Channel.
Hypothesis: Three Mills Wall River Weir is the sole feature that that maintains water levels in the Olympic Park in London.