Chaco Canyon’s Buffer Zone Issue With Oil And Gas Wells In New Mexico.

Originally published on on November 26, 2021

Engineering issues are not compelling in supporting a 10-mile buffer over a 5-mile buffer zone. But other factors, personal and spiritual, provide a different perspective.

On November 15, 2021, the Interior Department placed a 2-year pause of new oil and natural gas leasing on federal lands within a 10-mile buffer zone of Chaco Canyon. The Department is evaluating a longer ban for this area: 20-years.

This part of the San Juan basin has seen drilling of shale oil wells in the past ten years, as the Gallup sandstone in the middle of the Mancos shale can support stable wells that are slowly spreading toward Chaco Canyon.

Is this a standoff between Native Americans and oil and gas companies? Let’s look at the facts and the perspectives.

Buffer zones.

The Chaco Culture National Park in Figure 1 is about 11 miles long and mostly 4 miles wide (although one tiny point is 7 miles wide). A 10-mile extension all round would make this are roughly 31 miles long by 24 miles wide. The perimeter won’t be a box with straight sides, but this is an approximation. The area within the large box is a significant fraction (10%) of the San Juan basin that is 7,500 square miles in area.

The Chaco Park actually lies a little south of the oily Mancos shale, where oil production rose from 2.5 MMb/yr to 8 MM b/yr in the period 2012-2016. 

Figure 1. Present Chaco Park and rough boundaries based on 10-mile buffer zone. Source: EnCana

In an oil and gas conference in 2016 a radio personality declared there was no need for a 10-mile buffer zone around Chaco Park because underground cracks that result from fracking operations do not extend anywhere near 10 miles.

The man had a point. If you drill a 2-mile long horizontal well, and frac it 40 times along its length, the cracked up area is 2 miles long and roughly 1 mile wide. It’s a large area, 2 square miles, and if the well started 2 miles away it would be a problem. If the well started 5 miles away, it shouldn’t be a problem. But if the well started 10 miles away, at the new buffer line, it’s not going to affect Chaco Canyon directly. But what about indirectly?

If the water used in fracking finds itself in an open fault it could flow upward and toward the Canyon. A tremendous volume of fracking water is injected in a typical horizontal well: enough to fill a football stadium to 40 feet over the grassed area — and that increases the chance of this happening.

But many shale fracs, in different basins, have been tracked by their microseismic signals and these signals rarely show significant upwards frac growth. So fault activation by fracking a well at the 10-mile limit has a very low chance of impacting Chaco Canyon.

Earthquakes could be a concern, as they are in the Delaware basin of New Mexico, when wastewater from drilling and fracking operations is pumped down disposal wells. Such earthquakes can be felt at the surface, and can even cause structural damage several miles away.  A simple way to prevent this is to monitor earthquakes, and stop the injections if they become problematic.

If some of the fracking water is sourced from underground aquifers, the huge frac volumes can deplete those aquifers used by ranchers for agriculture or cattle or drinking water.

If the buffer is less than 10 miles, an argument goes, other forms of pollution such as noise and dust and traffic can spread when such complicated drilling and fracking operations are deployed.

But in Colorado, after much debate, the setback distance for a new oil or gas well from houses, schools and commercial buildings is 2,000 feet – based on protection for health, safety and environmental factors. So a 10-mile buffer seems a bit excessive from an engineering viewpoint.

None of these engineering issues provide a compelling preference for a 10-mile buffer over a 5-mile buffer. But there are other voices…

Different perspectives.  

But now Interior has as its Secretary Deb Haaland who is a member of the Laguna Pueblo in New Mexico — and that shifts the perspective. 

The ruins of Chaco Canyon are spectacular, multi-story structures (some 5 stories) built between 800 and 1200 AD (Figure 2). The building timbers must have been dragged from mountains 50 miles away. Linear roads had been constructed that spread out in some cases 50 miles or more.

Figure 2. Map of Chaco Culture National Historical Park.     Source: Wikipedia.

Less than 100 people lived there, based on size of rubbish tips, although the structures could have held thousands. The recent view is that Chaco was a gathering place for festivals or trade, not permanent living quarters. But then around 1150 AD the inhabitants dispersed, perhaps due to a 50-year long mega-drought.

The walls of the main building complexes are aligned with the end points of sunrise at the winter and summer solstices (June 21 or December 21). These points can be measured only once a year.  But some walls are aligned with a similar solstice for the moon, called a Lunar Standstill, which occurs only once every 18.6 years and requires patient measurements over a long time.

This is key. To Anglo visitors or companies who have drilled in the San Juan basin for oil and gas for the past 100 years, Chaco Canyon tends to be viewed as an outstanding collection of ancient ruins built with astronomical precision.

But to Native American Pueblos and Tribes, the perspective can be different. Some Puebloan people feel an attachment, even a reverence, for Chaco, as was explained to me by a Zuni tribal member who was looking over the kivas when I was visiting.  Other Pueblos also claim some heritage to Chaco Canyon.   

Figure 3. Kin Kletso Great House viewed from the clifftop.    Source: Ian Palmer.

Deb Haaland visited Chaco Canyon on November 22 to meet with Pueblo and Navajo leaders to get their inputs on the announced pause in leasing within 10 miles of the Chaco Canyon Park.

To Haaland, Chaco Canyon seems alive. “It’s not difficult to imagine, centuries ago, children running around the open space, people moving in and out of doorways, singing in their harvests, or preparing food for seasons to come. A busy, thriving community.”

Haaland said natural resources like Chaco Canyon need to be cared for by the government, like they were by the Chacoan peoples of 800-1200 AD.

Ownership of properties around Chaco Canyon. 

The land around sites like Chaco Canyon is like squares in a checkerboard that are owned by different entities. About a third of these is owned by the feds and administered by the Bureau of Land Management (BLM).

But some squares are owned by the state of New Mexico (trust lands), and they had declared a previous moratorium on new oil and gas activity on these lands within a 12-mile buffer zone.

When drillers in 2012 started finding oil in the Mancos shale, wells spread southward toward Chaco (Figure 1). Even though Chaco Canyon is nominally outside the oil window, the long horizontal wells and massive fracking operations seemed to reduce the separation underground.

Some alterations are permanent including well-pads, oil tanks, pipelines and roads. When added to the noise and dust and smell of fracking pumps, clanging rigs and roaring trucks, it’s easy to see why some communities put up their hands and cry out, enough is enough.

Daniel Tso was the only Navajo to attend the meeting with Deb Haaland on November 22. His opinion was that oil and gas activity, if not checked, could cause pollution that meant health problems for local inhabitants.

“(Navajo people) have great ties to the land,” Tso said. “Yes, we want the landscape protected. We want better air quality for the area. We want to protect the water.”

But the perception shifts when it comes to royalties. The Department of Interior indicates perhaps 50 leased allotments to 5,500 Navajo residents that receive over $6 million oil and gas royalties each year – within the 10-mile buffer zone. During Haaland’s visit some of these residents posted signs in protest of the leasing ban.

These existing leases, tribal allotments, or oil/minerals owned by various owners — private, state or tribal — would not be affected by the proposed 10-mile buffer zone.

But since production rates of oil and gas wells decline over time, such declines could not be replaced by new wells on new leases that are now forbidden. So this will have a negative effect for some owners.

Apparently because of this, in 2020 The Navajo Nation Council recommended a 5-mile buffer zone instead of the new 10-mile buffer zone.

The split Navajo position on the 10-mile buffer zone complicates the story, but more opinions will be solicited in an “open” discussion period with BLM lasting a few months.


None of the engineering issues provide a compelling preference for a 10-mile buffer over a 5-mile buffer zone.

The Pueblo Tribes support the 10-mile buffer zone, and seem to look at Chaco Canyon from a spiritual angle that includes awe and reverence for their ancestors and places where they lived and died. It appears to reflect a deep respect for the land and more sensitivity to pollution of various forms.

But the Navajo nation is split on the issue of the 10-mile buffer. One side wants to protect and preserve lands beyond the Chaco monument while another side doesn’t want to lose the royalty income from new oil and gas wells when present wells decline in production.

An open period for presentation to the Department of the Interior, via BLM, will be announced soon. BLM promised to formally consult with Tribes on the 10-mile buffer zone pause and its proposed extension to 20 years.

The Interior Department will also engage in evaluating the greater Chaco Canyon landscape, where outlier buildings were connected to Chaco by roads oriented by astronomical observations.


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