On the west a series of small lakes and backwaters receives water from the Juba during the rains.
Between Lechlade and Oxford the main channel sends off many narrow branches; the waters of the Windrush are similarly distributed, and the branches in the neighbourhood of Oxford form the picturesque "backwaters" which only light pleasure boats can penetrate.
These form the Cochin backwaters, which consist of shallow lagoons lying behind the beach-line and below its level.
Birds leave the slow moving river backwaters and streams and tend to move nearer to the coast for the winter.
Adjoining the lower Tana are many backwaters, which seem to show that the course has been subject to great changes.