Average annual rainfall in the High Weald is 35 inches (900 mm), and most of the underlying geology is impermeable, resulting in rain rapidly reaching the river and flowing down to the sea.

The river valley is thus prone to winter floods, while during the summer months, the flow can be quite low in dry periods, as there are few groundwater aquifers.

If heavy rainfall coincides with a high tide, where outflow is tide-locked, the river above the sluice to Bodiam acts as a huge holding reservoir for flood water, and is managed as such.

[13] Near its mouth, the River Rother no longer follows its ancient course, as it once flowed across Romney Marsh and joined the sea at Dungeness.

It is widely asserted that in 1287 a hurricane, known as the Great Storm, caused large quantities of shingle and mud to be deposited on the port of Romney and the mouth of the river.

[5] Rye became part of the Cinque Ports in the thirteenth century, and although it is situated some distance from the sea, its harbour is still visited by commercial shipping and has a fleet of fishing boats.

The Rother had been routed around the northern side of the Isle since the 1330s, when the Knelle Dam (grid reference TQ 852 269[16]) was built at the western end of the Wittersham Levels.

[17] From the 1600s onwards, much effort and expense had been spent trying to drain the Upper Levels, including the construction of the Great Freshwater Sluice below Appledore.

[19] Disaster occurred on Lady Day 1644, when an exceptionally high tide flooded the Upper Levels, and broke through the walls of the New Salt Channel.

The Commissioners authorised the construction of a new sea sluice at Kent Wall, and work began in May 1646, but in September, they decided that it should be built at Blackwall instead.

The height of Knelle Dam was regularly adjusted, in an attempt to manage the amount of water that still flowed along the Appledore Channel, and the conflicting needs of navigation and drainage.

[24] In 1723, the Commissioners of the Kent and Sussex Rother Levels employed the civil engineering contractor John Reynolds to make repairs to Scots Float Sluice, a timber lock on the lower river.

He built a dovetailed sheet pile wall below the foundations, and the Commissioners offered him the job of maintaining the levels in 1725, for which he would be paid £65 per year.

The main cargoes were manure, fuel and roadstone, and the places served by the river were listed as Appledore, Reading Street, Maytham Wharf, Newenden, Bodiam and Small Hythe.

Scots Float Sluice was described as being "very inconvenient and ill-adapted to the present vessels which navigate the Rother" by the civil engineer John Rennie in 1804.

Hostilities between the two countries ceased with the signing of the Treaty of Amiens in 1802, but in 1803, the Napoleonic Wars began, and there were fears that France would invade England.

The Rennie brothers, John and George, who had taken over from their father on his death in 1821, produced two reports on the river in 1830, as it was difficult to navigate and prone to flooding.

The last commercial barge to pass from the Rother through Iden lock onto the canal was the Vulture, carrying 27 tons of shingle on 15 December 1909.

[29] The river was used by pleasure craft in Edwardian times, when regular boat trips from Scots Float Sluice, then called Star Lock, to Bodiam Castle were offered.

Ten years later, these structures were replaced by unitary authorities, who had responsibility for the supply of drinking water and for the drainage function of rivers.

[40] The River Rother rises from several springs on the south-eastern side of Cottage Hill near Rotherfield in East Sussex.

The Rother flows towards the south east, picking up water from other streams, to reach the western edges of Mayfield, where it is crossed by the A267 road.

[42] The river curves to the east along the southern edge of Mayfield, passing a sewage works on the south bank and crossing under an abandoned railway embankment and a road at St Dunstan's Bridge.

[45] The railway line, which was following the valley of the Tide Brook, runs parallel to the river as it continues eastwards, passing to the north of Burwash.

Another tributary, which flows to the northwest from near a gypsum mine at Brightling, turns to the south and runs parallel to the Rother before joining it in Robertsbridge.

An attic bedroom had a wooden fireplace dating from the 1830s, but surrounded by medieval tiles described by the National Heritage List as being of "superlative quality.

[51] For the final 14 miles (23 km) from Bodiam to the sea, the bed of the river is below the high-water mark of neap tides,[52] and there are numerous drainage ditches traversing the valley floor.

Soon after New Bridge carries Wittersham Road over the river, the channel turns to the south, to run along the eastern edge of Walland Marsh.

[59] Nearby is an Inshore Rescue station, run by the Royal National Lifeboat Institution[60] The river then enters Rye Bay, part of the English Channel.

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 mercury compounds, neither of which had previously been included in the assessment.