Santa Ana River Watershed Timeline By york43k Period: Jan 1, 1810 to Apr 16, 2015 Santa Ana River Timeline Apr 1, 1810 First Rcorded Flood Apr 1, 1903 James Talbert forms Drainage District Apr 1, 1933 Orange County Water DIstrict is formed Formed to protect water rights Apr 1, 1941 Prado Dam is consrtucted Apr 1, 1955 Orange County adopts its first pollution ordinance Apr 1, 1964 Santa Ana River Mainstream Project is initiated Apr 1, 1983 Santa Ana Watershed Project Authority is formed Apr 1, 1989 Construction of the Santa Ana River Mainstream Project begins Apr 1, 1999 Seven Oaks Dam Completed
