US Warns Mexico Of Massive, Ongoing Sewage Spill Into Rio Grande: '150 Million Gallons Since August' A major pipe rupture on the American side of the US-Mexico border is sending millions of gallons per day of raw sewage into the Rio Grande , International Boundary & Water Commission (IBWC) is warning this week.  The agency formally notified Mexico authorities late this week, saying in a statement to the monitoring organization Border Report  that "The water that is going into the Rio Grande is downstream of the location where Mexico gets the water under the (U.S.-Mexico) treaty. [...]