A ruptured water main caused headaches for downtown Petaluma businesses and residents Monday morning. The rupture was reported around 5:30 AM Monday morning and city workers soon discovering that a 4-inch, cast-iron pipe had ruptured underground behind the Keller Street parking garage. Water had to be turned off in the area around 6 AM and remained off until the early afternoon. Initial repairs were actually done around 8 AM but, upon further inspections, crews determined a five-foot section of the pipe needed to be replaced.