Mineral monsters, skanky rocks, crazy egg cartons: Welcome to the aquifer!

 

mineral-monsterImage courtesy New Mexico Bureau of Geology & Mineral Resources. The obstruction, discovered in a 3200-foot well at nearly 1900-feet down, is believed to be zinc carbonate.

 

Through murky half-light, a subterranean water world percolates with activity. A video camera lowered into a 3,200-foot deep well in order records the scene:  large white flakes swirling, colliding and…growing.

Within a week, the resulting “mineral monster” sealed off the foot-wide casing, clogging it with an impenetrable barrier.

Hydrologist Peggy Johnson explained it to Taos County commissioners at their June 28 meeting, adding: “It’s Flint, Michigan. In reverse.”

Needless to say, her statement caused commissioners to sit up and take notice.

Johnson and husband-collaborator and principal geologist Paul Bauer are well known to water engineers, rafting guides, government officials, and well-drillers. They’ve spent twenty years reporting on the hydrogeology of the county. They provided critical data to negotiators of the Abeyta water rights settlement.

I had the chance to talk rocks and water with them over lunch in Socorro, home of New Mexico Bureau of Geology and Mineral Resources, where the two have built their careers and considerable reputations.

“We’ve taught each other a lot over the years,” said Johnson, looking across the patio to a row of giant sunflowers. “This is our last report.”  Johnson, who received a Community Service Award from the county, retired in August.

The report was commissioned in 2011 and cost the county $150,000, with an additional grant from the Healy Foundation. Johnson and Bauer estimate a truer figure for their Hydrogeologic Investigation of the Southern Taos Valley would be $600,000-$700,000.

Key partnering with USGS Denver on aeromagnetic, ground-magnetic and gravity surveys and analyses helped defray costs.

From 2011-2015, the team sampled 43 wells, three springs, and discharge from the Waste Water Treatment Plant.

The report is designed to help elected officials make data-driven decisions about development in neighborhoods that include Los Cordovas, Ranchos, Talpa, Vista Linda, Llano Quemado, and Tierra Blanca (the Stake Out area).

At the June commission meeting, commissioners appeared to emphasize different aspects of the data. For example, upon hearing that acequias play a crucial role in replenishing the shallow aquifer, Commissioner O’Donnell commented, “Retiring water rights from irrigation ditches could have the effect of lowering the aquifer.”

Commissioner Blankenhorn, on the other hand, highlighted the rich and plentiful groundwater supply. “These are great aquifers,” he said. Bauer would later tell me, “Taos is sitting pretty.”

Johnson told commissioners, “This area has the most complex hydrogeology of any place in New Mexico. I’ve never seen anything like it.”

What’s going on? Here’s the short and simple of a cautionary tale.

Near Ponce de Leon springs on the north side of Miranda Canyon, three complex fault systems converge. Blankenhorn, in a separate interview, described the area as “the crazy land.” And it is a kind of Bermuda Triangle.

The Embudo faults angle southwest from Talpa through the Rio Grande canyon and across the Espanola Valley.

The Picuris-Pecos system slices through deep basement rocks from Pecos northward through the Picuris Mountains and out along—but deep below—an apron of sediments that fill Taos valley.

The Sangre de Cristo fault marks the massive uplift of this range.

Rock layers span time from 1.7 billion years ago (back when New Mexico was a land of beaches and ocean) to the present.

Their make-up is extraordinarily diverse: deep crystalline rocks, limestones, sandstones, gravels, and more recent basalts (locally called, “lava rocks”).

Each fault system displaces these rock units up, down and sideways. When the systems collide in the Talpa area, the already displaced rock units are further stressed into an off-kilter maze of tilting, fractured blocks.

Now, imagine ground water trying to make its way through all this.

And as it flows, it picks up the particular chemistry of surrounding rocks. The geochemical analysis in this report sets it apart from previous studies.

The study area revealed three distinct—but interconnected—aquifers. Generally, water flows in a shallow aquifer along the valley’s rivers and also down slope from the mountains, and then drains northwest across what the report labels the Picuris Piedmont toward the Rio Pueblo.

  • The most productive water wells in the Picuris Piedmont aquifer are drilled in the valley-fill sediments of Ojo Caliente Sandstone and the Chama-El-Rito member.
  • Below these formations lie what Johnson calls “skanky rocks.” Water from this aquifer tends to be clay-rich and muddy.
  • Deeper still is highly fractured crystalline bedrock, which is where we find the deep confined aquifer.

A “zone of no recharge”—south of Miranda Canyon to the Stake Out—prevents ground water from even reaching the valley sediments. The Stake Out area has good water because it lies outside that zone and within a “hydrogeologic window” that allows water to flow through bedrock.

To understand the deep confined aquifer, Johnson asked me to imagine it as an egg-carton. “It’s like water comes up from below into an egg carton, but then gets stuck in these compartments.”

Water in the egg-carton can be 26,000 years old. Having flowed into the egg-carton from the crystalline rocks, it is super hot and bears a load of metallic elements.

Sometimes, as in the Ponce de Leon hot springs, this water rises through faults to the surface. Johnson and Bauer theorized that “there may be many little Ponce de Leons” out in the valley that never make it to the surface.

As you may have guessed, the “mineral monster” resulted from drilling into the deep aquifer and allowing water with widely different chemistries to mix. Rapid mixing led to rapid growth of what Johnson suspects is the mineral zinc carbonate.

The most vulnerable area to this kind of mixing extends from a few miles east of Rio Grande del Rancho westward beyond the golf course.

Could this happen elsewhere in the county?

“We just don’t know,” said Johnson. The craziness referred to by Blankenhorn could, in fact, “wrap around the base of the Sangre de Cristos.”

What about the regional ground water flow model related to the Abeyta water rights settlement? Johnson was unequivocal: “Groundwater flow models typically don’t consider the geochemistry.” Settlement provisions that call for drilling and developing deep supplemental wells may need to be examined in light of additional geochemical modeling.

Johnson offered this parting advice: “Make good decisions. Maximize what you have. Don’t be bold and stupid.”

 

2 thoughts on “Mineral monsters, skanky rocks, crazy egg cartons: Welcome to the aquifer!

  1. Lindsey Enderby

    Meg, Very impressive article in that you are able to outline a very opaque subject in lay men’s terms. Your friend, Lindsey

    PS: when you have time, I would appreciate my neighbor John Woods phone number and email address.

    Sent from my iPad

    >

    Like

    Reply

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