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Nitrate levels in groundwater have SLO County water quality officials concerned about rural residential wells

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Get tested. 

It sounds like that oft-repeated mantra from a sex education textbook. But, this time it has nothing to do with STDs. Actually, it’s all about groundwater. And specifically, it deals with nitrate—often used as a growing aid for row crops like strawberries and leafy greens.

Before your eyes roll back into your head and you stop reading, think about this: Wouldn’t you want to know what you’re drinking? 

Leslie Terry, an environmental health specialist with the SLO County Office of Environmental Health, thinks you should. And so does Angela Schroeter, a senior engineering geologist with the Central Coast Regional Water Quality Control Board. Why? During the most recent board meeting, Schroeter presented the results of two-plus years’ worth of testing about 4,000 groundwater wells on Central Coast farmland for nitrate contamination. 

“The important thing that we’re learning from this data is that nitrate contamination is pretty widespread on the Central Coast,” Schroeter told New Times. “And that’s significant because of the health impacts.” 

Too much nitrate can inhibit the blood’s ability to carry oxygen. It can lead to something known as blue-baby syndrome: Babies start to turn blue because oxygen isn’t getting where it needs to go in their bodies.  

In SLO County, of the 1,398 wells sampled, 14 percent exceeded the maximum contaminant level (MCL) for nitrate, which tops out at 10 milligrams per liter of water. Concentrations higher than that are considered to be unhealthy for humans to consume. Basically, if SLO’s city water tested above that standard, the water wouldn’t be delivered to customers. One well in the county tested at 12 times that standard, ringing in at 124 milligrams per liter. 

Monterey County is definitely worse off, with 34 percent of the 1,244 wells tested showing above that MCL. And Santa Barbara County? Of the 867 wells tested, 28 percent had nitrate levels above the MCL. One well held water with 870 milligrams per liter of nitrate: That’s 87 times what’s considered to be safe. 

“Many domestic well owners, and even the staff at county environmental health—the many counties: Monterey, Santa Barbara, SLO—were unaware of the scope,” Schroeter said. “So what we are trying to figure out at the water board is the best way to inform [people].”

A 2013 update to the Ag Order was put into place in part to make sure that people drinking water with excess nitrate levels are notified. Owners of farmed land with domestic wells that tested above the MCL are also required to provide safe drinking water to the people living on that land. 

However, Schroeter said the Regional Water Quality Board’s regulatory authority ends on farmed land—technically speaking, potential polluters. Residential properties without commercially irrigated land in the rural areas of the county are not required to test domestic wells for nitrate contamination.

“They’re not polluting, but they are being impacted,” Schroeter said. “If you’re on a domestic well, you should get your water tested every year.”

But nobody can make you do it. 

And that’s unfortunate, according to Terry with SLO County environmental health, because often people who live on wells don’t really know that much about them. They don’t know what’s in the water they consume—whether it’s nitrate, pesticides, arsenic, or whatever else. 

South SLO County had the majority of the hits for wells testing over the maximum nitrate level, which makes sense because it’s an agricultural area, Terry said, adding that it’s not the only area the county is worried about as far as drinking water goes.

“We’re concerned about everybody; we want everybody to test their water at the end of the day. And people are so reluctant to test their water, and I don’t really understand why,” Terry said. “A nitrate test is like $20. It’s like fill up a bottle and drop it off. … It’s so shocking why people don’t do it.” 

Editor Camillia Lanham found out it costs $25 to get water tested for nitrate at Abalone Coast Analytical. Email her at clanham@newtimesslo.com.

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