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.
The Three Mills Wall River Weir is no longer in existence today.
It's a possibility that it doesn't exist any longer, or was re-purposed - further reading would be required to validate the statement one way or another. I think the system was fooled because it doesn't realize 10 years have passed since the weir was built, and someone completely ignorant on the topic besides the given context would need to refer to other sources in order to confirm or deny the statement.