 The river then flows under the M32 motorway and parallels its course for a while before disappearing into an underground culvert at Eastville Sluices , upstream of Baptist Mills . It is joined underground by Coombe brook on the left and Horfield brook on the right . A brief stretch in St Judes is uncovered and then the river runs underneath Broad Weir , Fairfax Street and Rupert Street . At the site of the former Stone Bridge , near the junction of Rupert Street and Christmas Street , the main flow is channelled through <unk> Culvert . This follows the course of Marsh Street , Prince Street and Wapping Road , and joins the New Cut close to Gaol Ferry Bridge . The culverted section between Stone Bridge and St Augustine 's Reach is now a flood relief channel . 
