1938: Not until after a goal is scored….

"Anything goes in Water Polo …if you can get away with it”: “Not until after a goal is scored and the water is temporarily clear the referee be able to see if there have been any casualties in this scrimmage. Broken bones and ear drums are by no means rare in Water Polo, nor is it unusual for a man to sink to the bottom conscious…”.
Source: article of magazine “Look” of August 30, 1938