The bank notes were spotted floating in the South Drove Drain near Spalding town centre by a dog walker last month.
The money was retrieved from the river by officials, whose initial count estimated the cash to be around sixty thousand pounds.
A large amount of the money has been damaged but there is a good quantity of bank notes that appear to be in fair condition.
"It isn't everyday that an amount of money like this is found. Somebody must have information that will help trace the lawful owner," said Det Con Steve Hull, of Spalding CID.
Police are considering detailed forensic examination of the money. The money will remain with the police until the investigation is complete.