Sombrillo Area of Critical Environmental Concern

In 1988 8,865 acres of the Nambé Badlands were designated^[1]Resource Management Plan, March 1987, U.S. Department of the Interior, Bureau of Land Management, Albuquerque District, Taos Resource Area, BLM-NM-PT-87-006-4410 as the Sombrillo Area of Critical Environmental Concern (ACEC) in order to protect the internationally significant paleontological resources (fossils) found in the area. Significant paleontological resources found north of the 1988 Sombrillo ACEC, and identification of cultural resources, resulted in the BLM expanding the Sombrillo ACEC to 18,190 acres in 2010^[2]Draft Taos Resource Management Plan and Environmental Impact Statement, June 3, 2010, U.S. Department of the Interior, Bureau of Land Management, Albuquerque District, Taos Resource Area, … Continue reading.

Beginning in 2011, illegal mountain bike trail construction and irresponsible mountain bikers initiated significant damage to these resources and ecologically sensitive soils in this ACEC. The protections defined by the Sombrillo ACEC designation require official geological, paleontological, and cultural assessments prior to any surface disturbing activity. The illegal mountain bike trail construction, ongoing since 2011, includes using tools to carve out trails on sensitive ridgelines, cut trees (both pinyon and juniper), and cut new trails across virgin areas of biological soil crusts and stratigraphic layers.

The illegal trail building has accelerated in the area. What once was a beautiful area to hike, bike, and ride horseback is quickly becoming destroyed.

Map of the Sombrillo Area of Critical Environmental Concern in Northern Santa Fe County.

The Sombrillo Area of Environmental Concern consists of the three separated areas, as shown in this map.

Bureau of Land Management (BLM) Areas of Critical Environmental Concern, or “ACEC” designations, define areas where special management attention is needed to protect important historical, cultural, and scenic values, or fish and wildlife or other natural resources.

The 1987 Bureau of Land Management (BLM) Taos Resource Management Plan^[3]Taos Resource Management Plan, US Department of the Interior, Bureau of Land Management, Albuquerque District, Taos Resource Area, March 1987, BLM-NM-PT-87-006-4410 called for the protection of “significant paleontological resources” by designating the Sombrillo Special Management Area as an ACEC.

The Sombrillo ACEC was officially designated in 1988 with the mandate to protect significant and internationally recognized paleontological, geological, and cultural resources.

The paleontological resources in the Sombrillo ACEC (8,600 acres) are so important that they were specially called out in the 1987 Resource Management Plan for the entire Taos Resource Area (594,000 acres):

“Any surface disturbance within the Sombrillo area would seriously compromise the integrity and usefulness of these areas as internationally recognized bio-stratigraphic reference sections. This would cause irreversible and irretrievable damage to important paleontological resources.“^[4]Taos Resource Management Plan, US Department of the Interior, Bureau of Land Management, Albuquerque District, Taos Resource Area, March 1987, BLM-NM-PT-87-006-4410, Section 4, pp. 20-21

The illegal mountain bike trail, “North Arroyo Loop” (BLM trail segment #2P) was cut using tools into sensitive ridgelines containing paleontological resources in the Sombrillo Area of Environmental Concern (ACEC) in 2019. The BLM designated this area an ACEC in 1988 specifically to protect areas like this from surface disturbances! (Photo 12/11/2021)

The 18,077-acre Sombrillo Area of Critical Environmental Concern (ACEC) is shown on the larger Sombrillo Travel Management Area (TMA) map.

It is comprised of three non-contiguous areas
- 8,587 acres west of NM 503 and south of NM 76 (Zone 6 on this map)
- 653 acres south-east of La Puebla (Zone 2 on this map)
- 8,837 acres north of NM 76 (also Zone 2 on this map)

Zone 6, on the west side of NM 503, shown on this map, is the area where new (illegal) mountain bike trails are being constructed inside the Sombrillo ACEC. They have already caused significant damage to the environment that the ACEC was meant to protect. The fragile soils and exposed sedimentary strata in Zone 6 are easily damaged.

New mountain bike trails are also being constructed inside Zone 5, on the east side of NM 503, which is not inside the Sombrillo ACEC. The soils in Zone 5 of the TMA are firmer and more robust to mountain biking impacts than in Zone 6.

An internationally significant paleontological area

The BLM has documented the importance of protecting the paleontological, geological, and cultural resources that exist in the Sombrillo ACEC in ALL of its official Resource Management Plans (part of the BLM’s implementation National Environmental Protection Act and the Federal Lands Policy Management Act). Protection of the paleontological resources in the Sombrillo ACEC has been an enduring priority for the BLM and its stakeholders since at least 1987.

Below are excerpts from the official BLM land use plans on the requirements to protect paleontological and geologic resources in the Sombrillo ACEC.

1987 BLM Taos Resource Management Plan

Expand this section to see excerpts from the 1987 RMP...

“Paleontological resources are unique and non-renewable resources…” “The role of the BLM is to therefore manage and protect, where necessary, paleontological resources occurring on public lands.”

“Within this SMA are extensive exposures of the three most fossiliferous subdivisions of the Tesuque Formation, the Nambe, the Skull Ridge, and the Pojoaque, all part of the Santa Fe Group.”

“This fossil record in the Santa Fe Group is significant because it allows us to visualize the environment these animals lived in with great accuracy. In addition, the type sections ( or original references ) for the Skull Ridge and Nambe Members are located in this SMA. Although typically Santa Fe deposits are restricted to the Santa Fe- Espanola- Abiquiu area, they are best represented in this SMA.”

“This Alternative [B] places primary emphasis on maintaining or improving the condition of important paleontological values through the identification of the Sombrillo SMA. This recommendation and ACEC designation would protect significant fossils and ensure that important time and biostratigraphic benchmarks would remain undisturbed and available for future scientific study”

“ACEC designation of the Sombrillo SMA would facilitate preservation of a fossil record representing important evolutionary developments 15 to 5 million years ago. ACEC relevance criterion is met because it contains an important geologic reference section. ACEC importance criterion is met because the SMA contains time and biostratigraphic benchmarks, which are recognized both nationally and internationally. Without special management attention, these paleontological values will be susceptible to adverse and irreparable change in their natural condition and scientific function”

“This [Sombrillo] SMA is relatively undeveloped, as far as surface-disturbing activities are concerned. Because the area is scientifically important it should be managed to protect and preserve paleontological resources.”

2010 BLM Taos Resource Management Plan

Expand this section to see excerpts from the 2010 RMP....

“paleontology — coordinate with New Mexico Museum of Natural History to develop an inventory database for the ACEC”

“soils – restrict activities that disturb soil and vegetation to reduce soil loss and water quality impacts”

“visual resources – discourage land-use practices and development which adversely alters or eliminates the character of the badland topography in the ACEC”

“water – protect ephemeral channels to maintain stable hydrologic processes and appropriate vegetative communities as measured by diversity and cover density”

“wildland fire – implement limited fire suppression strategies to assist in the protection of paleontological resources”

Illegal trail, "Razor's Edge", illegally constructed using tools in the Sombrillo ACEC

Another illegally constructed mountain bike trail, “Razor’s Edge“, BLM trail segment #4P, freshly cut using tools into the sensitive resources the Sombrillo Area of Critical Environmental Concern was designated to protect by the Bureau of Land Management Taos Field Office

Requirements for Managing the Sombrillo Area of Critical Environmental Concern

The two pages to the right are copied directly from the BLM Taos Resource Management Plan, May 2012, BLM/NM/PL-12-09-1610, which is required by law under the National Environmental Policy Act.

Damage from newly constructed (between March 3-20, 2021) Illegal Mountain Bike Trail Construction in the Sombrillo Area of Critical Environmental Concern

↑1	Resource Management Plan, March 1987, U.S. Department of the Interior, Bureau of Land Management, Albuquerque District, Taos Resource Area, BLM-NM-PT-87-006-4410
↑2	Draft Taos Resource Management Plan and Environmental Impact Statement, June 3, 2010, U.S. Department of the Interior, Bureau of Land Management, Albuquerque District, Taos Resource Area, BLM/NM/PL-10-01-1610
↑3	Taos Resource Management Plan, US Department of the Interior, Bureau of Land Management, Albuquerque District, Taos Resource Area, March 1987, BLM-NM-PT-87-006-4410
↑4	Taos Resource Management Plan, US Department of the Interior, Bureau of Land Management, Albuquerque District, Taos Resource Area, March 1987, BLM-NM-PT-87-006-4410, Section 4, pp. 20-21