The 'International Wastewater Treatment Plant (IWTP) is a plant developed by the International Boundary and Water Commission (IBWC) in the South Bay area of San Diego, California.[1] Construction began on a 75-acre site, west of San Ysidro in the Tijuana River Valley. The project, authorised by the US Congress in 1989 and formally agreed between the two countries in July 1990, was part of a regional approach to solve a long-standing problem.
Completed in spring 1997, the official ribbon-cutting ceremony took place on 18 April and the plant came properly on-line in May.