[1] The course continues through Rushford, Thetford, Brandon, and Hockwold before the river joins the Great Ouse north of Littleport in Cambridgeshire.

More recently, Prof Richard West carried out a detailed field study of the area between 2002 and 2007, and his work was published by the Suffolk Naturalists' Society in 2009.

He concluded that the valley was caused by the runoff from a large glacial lake, which eventually melted, leaving the valley as it is today, with the sands of the lake bed becoming the sands of the Breckland, a large area of gorse-covered sandy heath that spans the border between Norfolk and Suffolk.

[9] Passing along the northern edge of Knettishall Heath Country Park, there are two weirs, after which the Peddars Way and Norfolk Coast Path cross on a footbridge.

The Black Bourn river joins from the south, and the combined flow turns to the north to reach Thetford.

The southernmost bridge, crossing the Little Ouse, dates from the late 18th century, and has two elliptical arches with a central cutwater.

[14] The northernmost crosses the River Thet, dates from the late 18th century, and has two elliptical arches, with splayed parapets and stone coping slabs.

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.

At Santon Downham, the Little Ouse Path continues along the north bank of the river, on the original towpath.

It lies at one end of the Foss Ditch, a waterway dating from the Saxon period that ran for 6 miles (9.7 km) between the Little Ouse and the River Wissey, which may have been used for defence.

[19] 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.

[20] 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).

[21] 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.

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 rodham, can easily be traced in the landscape, as its light-coloured bands of silt contrast with the dark, low-lying peat soils.

[5] The Environment Agency has designated the section from Thetford to Brandon, where it flows through the afforested Breckland, as a Flood Warning Area.

The Channel is a 28-mile (45 km) drain which runs from Barton Mills to Denver along the south-eastern edge of the Fens, and was constructed in the 1950s and 1960s.

[25] On its east side are two sluices, so that flood water from the upper river can be diverted into the Cut-off Channel and the section between there and the Great Ouse isolated.

The flood banks on this lower section are up to half a mile (0.8 km) apart, so that the meandering river can form a large lake.

Nearer the mouth of the river, the Brandon Engine was the main outlet for the drainage of the northern half of Burnt Fen from 1830[26] until 1958.

[30] There are references to its use by boats carrying goods to Brandon as early as the 13th century, and barges are known to have reached Thetford, some 6 miles (9.7 km) beyond Santon Downham when the river was tidal.

[31] Stone from Barnack, used in the construction of Thetford Priory in the 12th century, was almost certainly moved along the river, and improvements to the channel were authorised by the Commissioners of Sewers as early as 1575.

The tolls were leased to private individuals from 1850, but an attempt to transfer £320 to the Council finance committee from the navigation in 1859 resulted in nearly a year of legal wrangling, and ultimately the money was repaid in 1860.

[36] The state of the navigation declined steadily, although there was still commercial traffic, and a 25-foot (7.6 m) paddle steamer ran trips to Cambridge and around the local waterways in the 1880s.

[19] There is a campaign to re-open the river for navigation to Thetford, and the Environment Agency commissioned consultants in 2003 to look at the feasibility of such a project.

Like most rivers in the UK, the chemical status changed from good to fail in 2019, due to the presence of polybrominated diphenyl ethers (PBDE) and perfluorooctane sulphonate (PFOS), neither of which had previously been included in the assessment.