 Use has changed from pre-treatment water storage to first-stage run-off settling of suspended solids from the water filter beds at the adjacent works.This unused water flows in pipes to Sunnyside Reservoir for further settlement from which pipes discharge it to a lower reach of the river Thames than from which it was taken.The lakes narrowly exceed the embankments in size and have significant populations of moulting and wintering waterfowl, particularly where the water is shallow and marginal vegetation has developed.