Broken sewage infrastructure in Tijuana early this week sent roughly 7 million gallons a day of sewage into the Tijuana River, leading to beach closures along the south San Diego coast. The cause was a ruptured collector pipe in a part of the sewage system that has already received millions of dollars in upgrades in recent years, according to the International Boundary and Water Commission (IBWC), a joint U.S.-Mexico agency that oversees binational water issues.