sortedam lake is first mentioned in 1619 in the form "sorte dam" but it is unclear if "dam" (pond) at this stage referred to a small lake or a dam. the word "dossering" is derived from the french word "dos", meaning 'back', and refers to a path or road running on top of an embankment. the dossering was originally a small path. it later belonged to the water authority and was closed to the public by a locked gate at each end. residents at the bleaching ponds could obtain a key on the payment of a five mark deposit. the shoreline remained closed until the early 1850s.