VISTA —- The Vista Irrigation District will start adding fluoride to its locally treated water in late 2007 to coincide with a plan by a major Southern California water supplier to fluoridate all of the treated water it delivers to region, according to the district’s annual water quality report.
The report, released this month, describes how the Vista district, which uses a blend of water —- some treated at a local plant and some treated by the Los Angeles-based Metropolitan Water District —- will be affected once Metropolitan introduces the additive intended to prevent tooth decay.
Metropolitan, which supplies 80 percent to 90 percent of the water in San Diego County, expects to start fluoridating Oct. 1, according to spokesman Bob Muir.
Once that happens, the Vista district will start adding fluoride to the water it treats so there won’t be any dilution of the additive in its overall supply, said Roy Coox, the district’s assistant general manager.
In recent years, the irrigation district has received 75 percent to 80 percent of its water from Metropolitan, Coox said. The rest comes from the watershed and well fields around Lake Henshaw, a man-made reservoir about 40 miles east of Vista. The water from Lake Henshaw is piped to a water treatment plant that is jointly owned by the irrigation district and the city of Escondido.
Coox said it will probably cost the irrigation district about $20,000 to $30,000 a year to add fluoride at the treatment plant. Because Escondido already adds fluoride to its portion of the water there, it should be a simple process to fluoridate Vista’s water as well, Coox said.
“The injection point just needs to be changed,” Coox said.
Fluoridation of community water supplies has been a common, but occasionally controversial practice. Proponents, such as the American Dental Association, say fluoridation at the optimal level is a safe and effective way to prevent tooth decay.
Skeptics question those claims. In 2001, a handful of Escondido residents sued the city over fluoridation, arguing that it was dangerous and a violation of constitutional rights. The lawsuit was ultimately thrown out.
Muir said Metropolitan decided in 2003 to fluoridate the region’s drinking water “at the encouragement of the medical and dental health communities.”
The optimal level of fluoride in water is between 0.7 and 1.2 parts per million, according to the Centers for Disease Control and Prevention.
Metropolitan plans to adjust the fluoride concentration in its water from a natural range of 0.16 to 0.23 parts per million to 0.7 to 0.8 parts to million, according to the Vista Irrigation District’s report. The fluoride in Vista’s locally treated water will be raised to the same level from a natural range of 0.18 to 0.29 parts per million, the report states.
The Vista Irrigation District provides water to the city of Vista and portions of San Marcos, Escondido, Oceanside and unincorporated areas of the county.