Monet's famous lily pond at Giverny is not natural. Rather he had it made, diverting the Ru River into it. He enlarged it several times, necessitating permission from the city council, which included the proviso that "if this pond, which is for the cultivation of aquatic plants, should become a health hazard, the authorization granted to M. Monet could be withdrawn".
(Quote source: Monet's Years at Giverny, Metropolitan Museum of Art, p28.)
(Quote source: Monet's Years at Giverny, Metropolitan Museum of Art, p28.)