That storyline never happened in WWE. Here's what actually happened:
* The Rock and Stone Cold Steve Austin had a long-running rivalry. They were the top two stars in WWE during the "Attitude Era" and had many classic matches and storylines.
* The Rock won the WWE Championship multiple times against Stone Cold, including at WrestleMania 17 in a "No Disqualification" match.
* Their rivalry included many memorable moments, including a feud over the WWF Championship and a classic ladder match, but it never involved throwing anyone off a bridge.
It's possible you're thinking of a different wrestling storyline or a different event altogether.