In the small town of Simonton about 50 miles west of Houston, most of the 800 residents living near the raging Brazos River had been evacuated by mid-afternoon Monday, many by airboats, high water vehicles and dump trucks. In Simonton, the parking lot at city hall had become an impromptu staging area for law enforcement and fire fighters, some from as far away as Austin, to bring in residents stranded by the quickly rising waters.