In Victoria Australia at the former brown coal power plant Hazelwood, they did have a large lake of heated power plant water.  Boating was allowed on the lake and encouraged as was watersports.  About 15 years ago went waterskiing on the lake in the winter but as the water was warm you didn't need wetsuits.  The ancient 1950s built dirty coal plant is now closed as it was too expensive to keep running but it's good for the environment because it was the dirtiest coal plant in the western world.