Published: August 10, 2007 11:33 am      

Martindale wrestles with nitrates in water

Martindale — The last time Martindale Water Supply Corporation customers were notified of high levels of nitrates in the drinking water the problem was partially blamed on months of drought.

But a new notice those households received this week may have had its roots in just the opposite, the abundance of rainfall early in 2007.

According to MWSC Director Steven Fonville, a sample of water tested by the Texas Commission on Environmental Quality (TCEQ) in May showed a level of 12.9 milligrams per liter (mg/L); which is 2.9 mg/L higher than the Environmental Protection Agency’s maximum contaminant level (mcl) of 10 mg/L.

The sample was done as part of routine water quality testing and normally, TCEQ follows up with a second test in a week or so but Fonville said that didn’t happen.

“The guy never came back” and the MWSC had no further word from TCEQ until last week, when notice came that letters needed to be sent to all the corporation’s customers.

Fonville said after the May sample came back high, “we started monitoring ourselves four or five times a week, basically daily, getting ratings from 5.9 to 9.2 mg/L and none above 10.”

So, he theorizes the higher levels could have been the result of rainfall washing agricultural nitrate-based fertilizers into the alluvial aquifer from which MWSC draws its water.

“Please use discretion when applying nitrate-based (ammonia) fertilizers before rainfall events,” Fonville’s letter to customers said.

When high nitrate levels were reported in November 2006, Fonville said the MWSC would use water from the Hays/Caldwell Surface Water Plant it is a partner in to dilute the usual well water.

Should high levels return, they’ll do the same thing. “We will blend as necessary to keep levels below the maximum contaminant level,” he said.

Authorities say high nitrate levels don’t normally affect adults, older children, pets or livestock, but that infants under the age of six months should not consume water with high levels because the blood cells are not mature and the substance can interact negatively with hemoglobin.

Boiling water does not remove nitrates.



amiller@sanmarcosrecord.com