Originating from the village of Lower Beeding, just south of Horsham in West Sussex, the River Ouse winds it way through the towns of Balcombe, Ardingly, Barcombe and Lewes, terminating at the busy port of Newhaven in East Sussex. The tidal range at Newhaven is 4.7m and as a result the tide is felt as far up as Barcombe Mills, to the north of Lewes.

Once able to take sea-going ships all the way up to Lewes, the estuary has been heavily canalised, with levees and the removal of many meanders, from as far back as 1768. The name 'New-haven' itself indicates man's influence on this estuary: the current location of the mouth is not entirely natural. Prevailing winds from the south and south west cause the net movement of beach material along the Sussex coast to be eastwards (longshore drift), which has forced the mouth of the Ouse to move steadily in that direction. In the sixteenth century, the mouth flowed out at Seaford Head, approximately 5km to the east. Successive cuts through the shingle spit have allowed a much more direct route for shipping and prevented river water from backing up the estuary and flooding the fertile 'Levels' between Newhaven and Lewes. The current position of the mouth is held permanently by concrete harbour arms, the western one of which interrupts the longshore drift.

In more recent time, the Ouse has experienced problems with flooding, particularly in October 2000 when flood defences in Lewes were breached by a 1 in 200 year event which caused parts of the town centre to be covered by 3.6m of water. Downstream, however, the waters stayed within their channel all the way to Newhaven, which is the area the STONE project is focusing on.