The remains were recovered in the village of Cressage after a member of the public called the emergency services shortly before 9.15pm on Saturday.
Police and firefighters attended the scene and removed the remains from the water. They were confirmed to be a human shortly after.
West Mercia Police said the remains were likely to have been in the water for a significant amount of time.
“The death is currently being treated as unexplained,” the force said in a statement.
“An investigation has been launched and all lines of inquiry are being explored.”
Detective Chief Inspector John Weaver said: “We are in the very early stages of this investigation and inquiries are ongoing.
“Our priority at this stage is to identify the deceased.
“The remains are being forensically examined and the results will determine the next steps in our investigation. This could be a lengthy process but we will update the public in due course.”
There will continue to be a police presence at the scene over the coming days as inquiries and searches of the immediate area continue.