The Royal Parks advise that the swimming area in the Serpentine is open for swimming to the general public daily between June and September. Members of the Serpentine Swimming Club may use the swimming area throughout the year. The Serpentine swimming area was not closed during January 2009.
The Royal Parks (TRP) advise that they do not keep records going back 30 years about when and why the Serpentine swimming area was closed. In recent years TRP has never closed the swimming facility due to icy conditions. During the recent cold weather, access to the path immediately adjacent to the swimming area by the general public was restricted, because of safety concerns, after some visitors had walked on to the ice. The Serpentine Swimming Club has been allowed to operate throughout the period and has been issued with keys to the gates to allow the club access.
The Royal Parks does not retain full records going back to 1980 about the times the Serpentine has been closed to swimmers. I understand that there was only one short period during the late 1990s when the whole of the Serpentine was closed while remedial treatment was undertaken to deal with serious problems relating to algae.