Warnings as âdangerousâ River Witham runs high leaving litter behind in Grantham | Updated: 11:14, 02 February 2021 Banks look close to bursting along the River Witham through Grantham, after recent heavy rain and snow significantly raised the water level. Grantham RiverCare is warning the public of the dangers of rivers while in flooding conditions, especially around the likes of Harrowby Weir or the weir at the white bridge, which can be âquite dangerousâ, despite appearing shallow, according to RiverCare co-leader Ian Simmons. The group also highlighted that, althoug...