San Francisco Bay is becoming clearer.
Decades of tidal action have finally washed away most of the mess created 150 years ago by Gold Rush miners who blasted apart hillsides in the Sierra Nevada. The result was millions of tons of mud, gravel and sand that made its way downriver and ended up in the bay, clouding its waters and coating the bottom with a level of silt up to 3 feet thick.
Most of the silt, scientists say, has now moved out to the ocean.
