The branch covers the River Nene below Thrapston (above this point is covered by the IWA Northampton Branch) the Middle Level Waterways, Forty-Foot Drain (Horseways to Welches Dam) and the Old Bedford River (including the part from Welches Dam to Salters Lode Tidal Doors).
The River Nene links the waterways of the fens (the Middle Levels, The Cam, the Great Ouse and it tributaries) to the national waterways network through the Grand Union Canal Northampton Branch that joins the Nene just above Northampton Bridge. One of the best known features of the river are the guillotine gates at the bottom end of the locks. These are now being reduced in number as the Environment Agency has replaced some with conventional mitre door lock gates. The river is mainly rural in character as it progresses through 37 locks taking the boater from the Midlands plateau down to sea level. Although facilities on the river have improved in the last few years, with new moorings and services at Irthlingborough and the increased number of electrically operated guillotine gates, the river is still less well served than the Great Ouse or most canals.