Police were call by the ambulance service shortly before 7am on Friday following reports that a woman’s body had been found in the water (pictured are Police at the scene today)
The force said the country park is closed while its investigation continues.
Detectives were said to be treating the woman’s death as ‘an isolated incident’.
Detective superintendent Andy Smith earlier said: ‘The investigation is still in its early stages but we suspect that the parties involved are known to each other, with no wider threat to the community.
‘We understand this will have shocked and alarmed many people but officers will remain at the scene over the coming days and extra patrols are taking place to provide reassurance.
Suffolk Police said it detained the 46-year-old suspect at around 12.15pm (pictured are police at the scene today)
‘We would like to thank local residents who have so far assisted us with this investigation.’
Anyone with information is asked to contact the Major Investigation Team either by using the online portal at mipp.police.uk/operation/363718M87-PO1 or by calling 101 and quoting reference 37/17570/21.
Alternatively people can contact the charity Crimestoppers anonymously on 0800 555 111.