There are several watercourses around the Thames in Cookham which play an important role in drainage and flood recovery. They are a long-standing part of local farming activity and are important habitats for wildlife. They also provide the critical water supply to the 'Maidenhead ring' of the Maidenhead Waterways Project.
The River Thames splits into four channels downstream of Cookham Bridge: Odney Weir, the Cookham Lock Cut, Cookham Weir and the southernmost channel is called Lullebrook. West of these channels, the Fleet Ditch/Strande Water runs roughly north-south from Cock Marsh to Widbrook Common, running under the Moor Road (and over it during a flood) next to the NT car park. South of Cookham are the White Brook, which runs through Widbrook Common and under Sutton Road (or over it during a flood), and the Northtown/Maidenhead Ditch.
If you own land adjacent to a watercourse you have rights and responsibilities associated with it. In some cases the responsibilities include clearing vegetation and fallen trees. The government has this general guidance for landowners and the EA has published detailed advice about riverside trees (pdf, 586 kb).
The EA maintains parts of the main river and publishes its work programme on the gov.uk River and Coastal Maintentance Programmes page.