I know this is a silly title but I will explain! This is not a lake but a just a small part of a huge expanse of flooded farmland. The area that you are looking at was, in parts, awash wish floating turnips, particularly by the roadside. The view is from a bridge in the town looking across to the South Downs which are chalk hills that line much of the coast in the area.
Pulborough in West Sussex is liable to flooding but this is apparently the worst in living memory according to a lady who lives there. It flooded several houses and closed the main A29 road which goes south to the seaside resort of Littlehampton. Although the waters had gone down enough for the road to be reopened when we visited yesterday, water was bubbling up through the drain in the street. We have not had much rain in the last few days but the water table is laden with water.
I was inspired to visit the area having seen Brian's (Timecapturer) recent pictures of the floods at the close-by village of Stopham which has an ancient bridge next to a lovely old pub (damaged by the flood). The WS shows a picture of the bridge with the very high water level. Please see Brian's images as they are much better than mine!