Lincolnshire Police are continuing to work with specialist diver teams after a concern for safety call at Cradge Bank.
Police said they were called to Cradge Bank on Wednesday, January 9, at 10.50pm and had reason to believe a person had gone into the water.
They said: “An underwater dive team and police officers have been searching the area but we have not located anyone.
“Searches are on-going.”
Police have also launched an appeal, asking anyone with any information to call 101, quoting incident number 392 of January 9.