By Marlena Hartz
About half of New Mexico’s 160 dairies have groundwater beneath them that’s been polluted with nitrate, according to a New Mexico Environment Department internal review completed in January.
Dairy proponents, however, are questioning the meaning of NMED’s report, pointing out that groundwater contamination was a concern across the state before the population of dairy cattle began to swell half a decade ago. And both sides agree public water supplies near dairies are seldom deemed dangerous to consumers.
NMED officials say the report is an alarm bell, urging dairies to take more precautions to avoid contaminating the water supply. Dairy officials say the report inspires a lot of unanswered questions.
Lots of reasons
Sources of nitrate contamination are frequently too varied to be traced conclusively to dairies, said Walter Bradley, a spokesman for Dairy Farmers of America.
“It is premature to say this report pinpoints a single source,” he said. “In fact that’s wrong. Dairy producers are currently working with the Environment Department to gather the missing data in order to find the (offending) source or sources in order to protect our water.”
Buildup of nitrate underground can occur in a myriad of ways: from decomposing grass, from the rubber in tires, from government waste plants and landfills, from playas once used for waste storage, highway runoffs, old feedlots and from septic tanks, Bradley said.
Indeed, said Adam Rankin, NMED director of communications, groundwater pollution associated with septic tanks dwarfs that caused by dairies. And the Department toils to nail down more exact causes of nitrate contamination whenever it occurs, Rankin said.
“Dairies are a problem,” he said, “but they aren’t the largest problem in terms of groundwater contamination. Septic tanks are.”
Feedlots also are a primary source of nitrate contamination, but they do not produce a daily discharge as dairies do. So the state Environment Department does not regulate that industry with a permit system, as it does with dairies. Instead, the federal Environmental Protection Agency regulates stormwater collection ponds at feedlots.
impact drinking water
In the past three to five years, the New Mexico Environment Department has shuffled and fortified monitoring wells used to test pollutant levels in groundwater near dairies, Rankin said. At the urge of the Department, many dairy owners moved monitoring wells closer to their dairy cows. The Department can better gauge nitrate levels that way, Rankin said, as manure is a primary source of nitrate. Other wells, also at the request of the Department, were completely redesigned because they weren’t built properly, he said.
The January review, the first of its kind, was drawn from newly gathered data, available because of the aforementioned monitoring changes. Rankin said: “(The report) is definitely a concern because groundwater is the primary drinking source for most of the state. Without (potable) water, we are in trouble. There is no doubt that the number of dairies with concentrations of nitrate in groundwater is increasing.”
Rankin links the increase to his department’s evolving pollution monitoring.
Excessive nitrate levels in drinking water can cause serious illness and sometimes death, states the U.S. Environmental Protection Agency Web site. Ten milligrams of nitrate in one liter of water deems it contaminated, according to state standards. Milligrams of nitrate underneath dairies, and across the state, vary. But the primary concern at the Department is protecting public drinking water supplies from collecting more than 10 milligrams of the chemical, or any other pollutant, Rankin said.
Nitrates found underneath dairies are almost always diluted before they contaminate public drinking water systems. A slew of factors, including soil density and the location of a drinking water system, affects whether drinking water is contaminated, Rankin said. Unless notified otherwise, public drinking water in New Mexico should be assumed safe, since the Department tests public supplies routinely, he said.
No public water supplies in eastern New Mexico are unsafe for drinking, Rankin said.
Citations of dairies for nitrate contamination are rare, officials said.
“Just because there are exceedences of the state groundwater standard for nitrate does not mean that we automatically cite the responsible party,” Rankin said. “We normally impose additional requirements on their operations to further protect groundwater. … We only move on to compliance orders when the responsible party is uncooperative and that hasn’t happened yet.”
Las Cruces has
More than one-third of the state’s dairies are spread across Roosevelt and Curry counties. Of 21 active dairy sites in Curry County, four have deposited excessive levels of nitrate in the groundwater beneath them. All four contaminations occurred because the ponds used to collect dairy waste, called lagoons, failed, the Department concluded. Of the 17 Curry County dairies that do not show contamination, five have an increasing trend of nitrate in their groundwater, according to the NMED review.
Of 32 active dairies in Roosevelt County, 16 have groundwater with nitrate levels above the state standard, the NMED review shows.
Those figures are sunny compared to other regions in the state, Rankin said.
“The situation in Curry and Roosevelt is better than in other places because the depth to groundwater is several hundred feet,” Rankin said.
Fifteen dairies, the bulk of them in Las Cruces, have been ordered to clean up contaminated groundwater supplies. Elsewhere, the situation has not reached such urgency, he said. “(Las Cruces) is the area we wanted to address first because we saw problems there.”
Best liner debatable
Dairy proponents agree waste management is an important issue. What’s the best way to manage waste? Opinions vary.
Nitrate problems commonly stem from shoddily lined wastewater lagoons, Rankin said. Cracks and leaks in lagoons made of clay are not uncommon, he said. To counter the problem, the Department requires clay lagoons with extensive leakage problems to be lined with a synthetic material separating the sludge inside from the ground.
“We learn, and then the dairies learn, the best way to manage their waste,” Rankin said.
Art Schaap, a Curry County dairy farmer, maintains officials from the Environment Department do not always know how best to operate a dairy — or the best way to confine dairy waste. He praises the very system scrutinized by the Environment Department, clay lagoons.
“Clay is like the skin on your arm,” he said. “If you damage it, it is like cutting your arm. You can fix it easily by adding more clay. Synthetics are like a shirt. If you tear a part of the liner, you will have to replace the whole liner. In actuality, it is better to have clay.”
Lining a lagoon synthetically can cost a dairy farmer more than $200,000, Bradley said.
And Schaap sees the need for environmental regulations even though they can be irksome — especially when they result in costly changes he views as unnecessary.
“There is always a bad apple in any bunch,” he said.