Poche Beach, a county-owned spit of sand between Dana Point and San Clemente, California had a problem with water quality as a result of storm water runoff with pollutants and bacteria that flowed right into the Pacific making the water unsafe for bathers. Recently, officials in the area dedicated a $3 MM treatment facility using UV to reduce the amount of bacteria entering the beach area.
The city of Dana Point in 2006 invested in a $6 million treatment plant in Salt Creek. That project used ozone instead of ultraviolet light, the first time ozone was used to treat urban runoff. Ozone was used against runoff in Dana Point because the Salt Creek water was not clear enough for UV light to penetrate it and kill bacteria. The state contributed $4 million to that project. Salt Creek has not had a single water-quality advisory while the plant was running. Dana Point also has added a smaller ozone system to a creek that runs between San Juan Creek and Dana Point Harbor.
The project demonstrates that ozone can be an effective means to treat storm water runoff to reduce bacterial loads. In this case, to make the beach safer for those who want to enjoy ocean bathing, ozone can provide excellent disinfection, especially where the water cannot be economically treated with UV. Ozone not only purifies the water, but also leaves behind no residual that other disinfectants such as chlorine might.