These small ponds can be found scattered across the South Downs, wherever sheep and cattle traditionally went for summer grazing.. Surviving ponds probably number at least 500 across England, although they are often overgrown nowadays, their banks badly trampled by livestock, serving as little more than picturesque havens for butterflies or a romantic spot for picnicking ramblers.
They still have a magical and highly significant property. ‘People have noticed that they rarely run dry, even in the hottest summer, and it is apparent that, during the night, they receive a supply of water sufficient to counter-balance the great drags that are made upon them by cattle and evaporation,’ notes Edward Martin, in a research paper entitled Dew Ponds: History, Observation and Experiment.
The great mystery is where the water that fills them up at night can come from. These ponds – also known as ‘mist ponds’ or ‘fog ponds’ lie on the downs far above the level at which streams begin to form, nor does any piped-water supply reach them. The name ‘dew pond’ is the clue. According to folklore, it is the overnight dew itself, falling on the round-backed downs and on the ponds themselves, that keeps them full, whatever the weather …