An aerial view of Valmont Butte in 2006
An aerial view of Valmont Butte in 2006 ( JOSHUA LAWTON )

The Boulder County commissioners approved a cleanup plan for Valmont Butte on Monday with the conditions that the city landmark the four-acre historic mill site as well as parts of the property that may be culturally important to Native Americans and the area's first settlers.

The 100-acre butte, city-owned but located in unincorporated Boulder County, is contaminated with toxic tailings from the gold and fluorspar ore that has been milled at the site in the last century.

The cleanup plan involves excavating about 300,000 cubic yards of polluted dirt and concentrating the earth in a single location that would be covered with a prairie dog-proof rock cap.

Historic preservationists, descendants of early settlers buried in a cemetery at the foot of the butte, and representatives of Native American tribes -- which consider the site sacred -- asked the commissioners Monday to make sure that the area's cultural resources are adequately protected during the cleanup.

Part of the challenge, however, is that the locations of all culturally significant areas are not yet known and some -- such as buried artifacts and, potentially, human remains -- may not be discovered until the excavation begins.

County staffers, with guidance from the Historic Preservation Advisory Board, recommended that the county require the city to apply to landmark the mill site -- which includes accessory structures such as the water clock building and the scale house -- within four months of cleanup completion.


Staffers also recommended that the city be required to apply to landmark the entire, 100-acre butte as an archaeological area within a year of cleanup completion.

But the city argued Monday that it is only necessary to landmark 12 additional acres to protect areas of significance to Native Americans. Another 27 acres of the area are already protected as open space.

Steven Moore, an attorney at the Native American Rights Fund, told the commissioners that he disagrees with the city and supports landmarking the entire area. He told the commissioners that the lines drawn by the city seem arbitrary and that some of the areas not proposed for protection do have cultural value.

"We walked that area with Native American leaders several years ago, and they were pointing out artifacts on the surface," said Moore, who was speaking on behalf of the Valmont Butte Heritage Alliance.

The county commissioners agreed with Moore that there could be important artifacts outside of the area suggested for landmarking by the city.

"My sense of it is that, on the landmark question, I would like to see more of the site landmarked than just the (area proposed by the city)," said Commissioner Cindy Domenico. "I would rather have us not lose potential and cultural resources that are there. I'd rather have the landmark process to protect them."

But the commissioners also did not want to landmark areas that may prove not to be culturally significant.

Ultimately, the three-member board agreed to require the city to file a landmark application for the entire site -- minus the largest tailings pond where the excavation dirt will be centralized -- within a year of completion. County staffers will then work with the city to decide whether more areas can be removed from the landmark application due to lack of cultural importance.

Commissioner Will Toor voted with his colleagues but expressed some concerns over the plan. He said he thought it would make more sense to first identify which areas are significant and then file the landmarking application, not the other way around.

"This seems like a level of requirement that I guess I haven never seen applied in any previous case," he said. "It seems odd."

The commissioners also approved the city's plan to have a tribal monitor and an archaeologist on site when the area is being excavated to identify culturally important artifacts that may be exposed.

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