From 1960 to 1965 the population in the San Gabriel Valley increased by more than 31 percent. It was a rate of 30,000 new residents per year. By this time the Upper San Gabriel Valley Metropolitan Water District was purchasing water from the Colorado River to replenish the local groundwater supply for the increasingly thirsty valley.

In 1961, the City Council adopted the City’s first zoning ordinance to keep the robust building organized and controlled. The zones provided were Commercial, Manufacturing, Manufacturing-Agricultural, and Manufacturing-Public Buildings.