Perchlorate FAQ

Q1: What is perchlorate?
A1: Perchlorate is a salt used in rocket fuel, munitions, fireworks and explosives. It is also a component of air bag inflators, an additive in lubricating oils, tanning and finishing leather, fabrics and dyes, electroplating, aluminum refining, fertilizers and in production of paints and enamels.

Perchlorate helped build Cold War-era weapons. It was used in rockets that put people on the moon and space shuttles in orbit. It also was used for more mundane uses such as in making fireworks in San Bernardino County.

Q2: How far reaching is perchlorate contamination?
A2: Perchlorate water contamination first gained statewide attention as a drinking-water concern in 1985 after the Environmental Protection Agency (EPA) detected perchlorate in wells servicing households in the San Gabriel Valley (Aerojet's original facility, near Los Angeles).

Over the past decade, perchlorate has been found throughout Northern and Southern California.

The cities of Colton and Rialto are currently addressing an underground perchlorate plume that affects 75 wells and closed 20 wells that could supply 120,000 families.

Q3: How does perchlorate impact public health?
A3: The California Office of Environmental Health Hazard Assessment (OEHHA) links perchlorate consumption to impairing thyroid function. The EPA advises that it is premature at this stage to interpret risk estimate in the water standard for this contaminant. At some level, EPA advises perchlorate interferes with the ability of the thyroid to utilize iodine to produce thyroid hormones. It is important to note that perchlorate was used as a medicine for years to tame hyperactive thyroids.

The State Department of Health Services (DOHS) does not believe any health effects would result from a perchlorate level of 6 ppb. OEHHA has set California's current perchlorate Public Health Goal (PHG) at 6 ppb. One part per billion is roughly equivalent to one drop of water in an Olympic-sized swimming pool.

As DOHS makes a determination of the Maximum Contaminant Level (MCL) or Safe Drinking Water Standard, DOHS has set an action level for perchlorate at 6 ppb to be in line with OEHHA's PHG. If the water tested exceeds the action level, then notification requirements must be made.  If the water tested exceeds the action level by a factor of 10 (for perchlorate it's 60 ppb), then the water must be removed or treated prior to use. EMWD has made all of the appropriate notification in Perris Valley and Moreno Valley. None of our wells exceed 60 ppb. In fact, our wells are blended and  perchlorate has not been detected in the blended water used within our system.

Q4: What are the sources of perchlorate contamination?
A4: The Colorado River is a main source of perchlorate contamination. This is a serious problem since roughly a third of Southern California's drinking water comes from the Colorado River. Experts point to a former ammonium perchlorate manufacturing facility in Nevada as the origin of the contamination.

Most of the perchlorate contamination appears to be the result of past activities in the aerospace industry. Kerr-McGee has been a significant manufacturer of perchlorate and began a clean-up effort in 1999. At that time, 900 pounds of perchlorate a day entered the Colorado River through that site.

Currently, 500 pounds of the chemical is finding its way into a wash that empties into Lake Mead. From there, the water is carried to 17 million people in Southern California via the Colorado River Aqueduct. By 2005, the amount is expected to drop to 50-100 pounds a day.

The Nevada division of EPA believes the clean up will allow the river water to meet the state's (Nevada) public notice standard of 18 parts per billion (ppb).

The perchlorate detected in the EMWD wells is coming from the groundwater basins.The source of contamination has not been determined. Potential sources include Colorado River Water as it has been used in the valley for many years or use of fertilizers containing perchlorate as the area is primarily agricultural.

Q5: What is the State of California doing to remedy this problem?
A5: State Senator Nell Soto has introduced legislation to increase water protection and require polluters to replace lost water supplies.

California Department of Health Services has adopted a public health goal of 6 ppb for drinking water. A well that exceeds the current perchlorate action level (6 ppb) can be blended to legal levels and local governments must be notified. State officials expect to enact a maximum allowable drinking water standard some time this year.

Q6: Is there perchlorate contamination in the EMWD service area?
A6: Eastern Municipal Water District has three water wells that contain perchlorate. All three of these wells are blended with State Project water from the Mills Filtration Plant until the perchlorate level is below the detection limit of 4 ppb . All blending is done at each of the well sites and before the first customer service. At no time has EMWD served undiluted well water containing perchlorate to customers .

These wells represent approximately 1.7 % of the total water served by Eastern Municipal Water District.

Q7: Why does EMWD water have higher perchlorate levels than anyone else?
A7: Perchlorate has been detected in many areas in Southern California and in Riverside. EMWD's levels are not considered to be the highest in our area. Water sources that have 60 ppb or more have been removed or are treated prior to use.

Q8: What is EMWD doing to reduce levels of perchlorate in the local water supply?
A8: EMWD strives to remain an industry leader in environmental consciousness by using blending treatment techniques that result in water that complies with all environmental, health and safety regulations.

EMWD is closely monitoring the blended water from affected well systems to ensure that perchlorate is not entering the water system above the current action level of 6 ppb.

EMWD has also requested faster cleanup of the Colorado River chemical contamination from the Henderson, Nevada facility.

updated: March 15, 2006