Officers were called to Fourth Avenue shortly before 2pm on Saturday 31 December following reports of a suspicious object in the water.
Specialist forensic officers have since confirmed that these are human remains.
An investigation with Essex and Kent Serious Crime Directorate is underway and early enquiries are ongoing.
Detective Chief Inspector Antony Alcock said “It’s the really early stages of this investigation and we are working to determine what has happened.
“ I understand that this is concerning news for local residents and our officers are likely to remain in the area for the next few days to continue enquiries.
“We ask that the public respect the cordons in place and we will be updating the public as the investigation develops.”
More news from Essex
