This new fence at Swanshurst Park is a typical example of excessive safety measures put in place by Birmingham City Council and is also typical of the emerging 'nanny state'. Thankfully, the fence is only around part of the lake/pond.
Swanshurst Park is a fairly small park off Swanshurst Lane and Yardley Wood Road, comprising a sloping field, a few grassy paths and a path around a small lake/large pond.
Until the end of the Second World War, the park was used as common grazing land, then the land was given to the City as parkland and a nine hole pitch and putt were added in the 1950s. In the 1990s this was closed down and most of the site has returned to its more natural heathland condition making it an important nature conservation habitat.
According to Birmingham City Council's website, there are two large pools within the park, but I only know of one and Google Maps shows only one. I've sent an enquiry to the council about this - it will be interesting to hear from them about it.
EDIT: I received a reply today (24th July) from the council:
Hello [name] - thank you for your recent enquiry regarding pools in Swanshurst Park. The second pool identified on the website relates to a pool/boggy wetland area located in the bottom portion of the park. During winter this is quite a large body of shallow water but in drier months tends to dry out and become more boggy.
Hope this answers your question