News Update: Mil Potrero Mutual Water Company Blends High Arsenic Levels to Healthy Standards

By Patric Hedlund
Pine Mountain (November 2, 2010, 5 p.m.)—A newsletter notice was distributed to residents of Pine Mountain on October 22 reporting that the water system has one well, Well 7, which has tested for arsenic levels above the state’s current standards. The state standards were changed recenlty, according to Mil Potrero Mutual Water Company employee Cameron Acosta. She said that the water in Well 7 has tested at .019 mg/L for many years—and that was within state acceptable levels (which were .050 mg/L) as the Maximum Contaminant Level (MCL) until the acceptable state MCL standard for arsenic was recently lowered to .010 mg/L.

"But," Acosta continued, "Although the tests are taken at the well, none of the water in the tanks that supply our homes has readings at that level; all readings at all tanks are below the state standards."

How do they do that? All water from each of the active wells is pumped to the MPMWC water treatment plant (located near Lampkin Park) where it is filtered and blended with water from other wells, then pumped to the storage tanks, Acosta explained.

Below is the notice from the MPMWC website (


Our water system recently violated a drinking water standard. Although this is not an emergency, as our customers, you have a right to know what you should do, what happened and what we are doing to correct this situation.

We routinely monitor our water supply for the presence of drinking water contaminants. Based on the resulting samples collected from November 9, 2009, (4th Quarter 2009) to July 27, 2010, (3rd Quarter 2010) the drinking water produced by Well 07 in our water system contained an average of 19 ug/L (0.019 mg/L) of arsenic. Well 07 produces water that is above the standard, or maximum contaminant level (MCL), set by the State of California Department of Public Health of 10.0 ug/L (0.010 mg/L). This standard is based upon the running annual average of the most recent quarterly arsenic monitoring.

What should I do?
You do not need to use an alternative water supply (e.g., bottled water).
This is not an emergency. If it had been, you would have been notified immediately. However, some people who drink water containing arsenic in excess of the MCL over many years may experience skin damage or circulatory system problems, and may have an increased risk of getting cancer.
If you have other health issues concerning the consumption of this water, you may wish to consult your doctor.

What happened? What is being done?
We are working with the California Department of Public Health to find a solution for our high arsenic problem.

For more information, please contact Steve Wieneke, General Manager, Mil Potrero Mutual Water Company at (661) 242-3230 or the California Department of Public Health at (661) 335-7315. This notification of all water users is being performed in compliance with law and regulations of the California State Department of Public Health to keep you, the affected public, fully informed.




This is part of the October 29, 2010 online edition of The Mountain Enterprise.

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