Editing River Little Ouse (section)

===Below Thetford===
Below the pool site, the river is joined by the River Thet, where there is a network of channels, sluices and weirs, together with the remains of a water mill, dating from the early 19th century. The building is now used as a masonic lodge. As it threads its way through the town, the river is crossed by Town Bridge, a single elliptical [[cast iron]] span dating from 1829,<ref>{{NHLE |num=1195954 |desc=Town Bridge |access-date=7 October 2017}}</ref> and after it passes under the A11 Thetford Bypass, it is bordered by [[Thetford Forest]]. This is the largest manmade lowland forest in Britain, covering {{convert|72.3|sqmi}}.<ref>{{cite web |url=https://www.forestry.gov.uk/thetfordforestpark |archive-url=https://web.archive.org/web/20190520105617/https://www.forestryengland.uk/thetford-forest |archive-date=20 May 2019 |url-status=live |title=Thetford Forest |publisher=Forestry Commission |access-date=7 October 2017}}</ref> There is a weir beyond the bridge, and the county border rejoins the river as it turns back towards the west. This section is easier to follow, as the St Edmund Way footpath runs along the north bank from the centre of Thetford, but leaves the river where the county boundary joins. The St Edmund Way continues to the north of the river, and the Little Ouse Path runs to the south. At Santon Downham, the Little Ouse Path continues along the north bank of the river, on the original towpath.<ref name=osmap/>

The footpath leaves the river just before the A1065 bridge at Brandon, but rejoins it soon afterwards. Brandon Lock follows, with the lock chamber to the north and a large weir to the south. The [[Breckland line|Ely to Norwich Railway line]] crosses from the north bank to the south, and there is a Romano-British settlement site on the north bank. It lies at one end of the Foss Ditch, a waterway dating from the Saxon period that ran for {{convert|6|mi}} between the Little Ouse and the River Wissey, which may have been used for defence.{{sfn |Blair |2006 |p=78}} The towpath stops following the river to the south of Hockwold cum Wilton, turning to the north.<ref name=osmap/> The river has been diverted from its original course, to cross the [[Cut-off Channel]] in a concrete aqueduct. Large guillotine sluices control whether the water is fed into the lower river or along the Cut-off Channel.{{sfn |Blair |2006 |p=78}} As it rejoins its original course, it passes under Wilton Bridge, and there are footpaths on both sides, set back from the channel on flood banks.<ref name=osmap/>

To the south of the river are a series of washes, meres and wooded stretches.{{sfn |Blair |2006 |p=73}} Parts of this area were formerly arable farmland, but were converted into the Lakenheath Fen wetland by the [[Royal Society for the Protection of Birds]] (RSPB). The reedbeds and grazing marshes have attracted significant populations of reed warblers, sedge warblers, bearded tits, marsh harriers, and increasingly, bitterns.<ref>}{{cite web |url=https://www.rspb.org.uk/reserves-and-events/find-a-reserve/reserves-a-z/reserves-by-name/l/lakenheathfen/about.aspx |title=About Lakenheath Fen |publisher=RSPB |access-date=9 October 2017}}</ref> At the western end of the fens is Botany Bay, where water from Lakenheath Old Lode and the Twelve Foot Drain is pumped into the river. A little further on is the confluence with another drain, called Lakenheath New Lode.<ref name=osmap/>

The final {{convert|6|mi|sigfig=1}} of the river follow a relatively straight course which heads north-west to join the River Great Ouse at Brandon Creek. The channel is man-made, and probably dates from the Roman period. Prior to its construction, the river continued due west, and joined the Great Ouse near Old Bank Farm. Its dry raised bed, known locally as a [[Roddon|rodham]], can easily be traced in the landscape, as its light-coloured bands of silt contrast with the dark, low-lying peat soils.{{sfn |Blair |2006 |p=73}} It is also clearly shown on the modern Ordnance Survey map, delineated by the 0&nbsp;ft contour.<ref>{{cite web |url=http://www.streetmap.co.uk/map.srf?x=559622&y=286246&z=115&sv=559622,286246 |publisher=Ordnance Survey |title=1:25,000 map |access-date=9 October 2017}}</ref> On the river channel, there is a pumping station on the north bank, and the course passes between the hamlets of [[Brandon Bank]] on the north bank and [[Little Ouse, Cambridgeshire|Little Ouse]] on the south. Nearby is the lowest [[trig point]] in Britain, marking a spot which is {{convert|3|ft|m}} below sea level.<ref>{{cite web |url=https://www.bbc.co.uk/news/in-pictures-36036561 |archive-url=https://web.archive.org/web/20201116173845if_/https://www.bbc.com/news/in-pictures-36036561 |archive-date=16 November 2020 |url-status=live |title=The trig pillars that helped map Great Britain |publisher=BBC |date=17 April 2016}}</ref> Its junction with the Great Ouse is immediately after it passes under the A10 road.<ref name=osmap/>