New fence to protect Niwot's rare Fox Hills Sandstone formation

Boulder County Parks & Open Space has recently completed a new fence along the Niwot Loop Trail on the south side of Somerset to protect a critical and rare habitat.

Working in conjunction with the Niwot Community Association and the Somerset Estates HOA, Boulder County installed the four-foot-tall Jackleg fence as a barrier to help protect the natural area.

Therese Glowacki, manager of the Resource Management Division of Boulder County Parks & Open Space, was part of the team that helped identify and then take the necessary steps to protect this open space area. Glowacki has been working with Boulder County Park Services for over 21 years and noted that there are several different layers in the process of designating open space as a protected natural area.

This particular area, known as the Niwot White Rocks, is an area of white and buff-colored exposed Fox Hills Sandstone found on the hillside south of Somerset. The land, which Glowacki said was purchased as open space a few decades ago, most recently came to the county's attention in 2014 when they updated the environmental resources element of the Boulder County Comprehensive Plan.

"In doing that, we looked at unique habitats and determined that the Niwot White Rocks had rare species, both plants and animals," Glowacki said. "We also knew that it had lichens, even though they hadn't been thoroughly determined yet,"

After the update to the BCCP in 2014, lichen researcher Erin Tripp from the University of Colorado discovered a new species of lichen found at both the White Rocks in Niwot and the White Rocks in Boulder off of 75th Street.

The area is also home to other rare and important species such as miner bees. A species of Perdita opuntia, miner bees are a type of ground-dwelling bee that burrows into the ground or makes nests in the natural cracks of the Fox Hills Sandstone formation.

"There's a huge issue with pollinator decline in the United States and around the world," Glowacki said. "Part of our mission is to protect any sort of rare or unique pollinator habitats."

And more broadly, the area is part of a Needle and Thread grass community which is home to several rare grasses and also rare forbs, a type of herbaceous flowering plant.

"We had those pieces of information-critical plants, rare plants, rare bees-and then we'd been working with a geologist who brought it to our attention that Fox Hills Sandstone is a rare geologic formation that has made its way to the surface, and we need to protect it," Glowacki said.

Sue Hirschfeld, a retired geologist and Boulder County volunteer naturalist, was an instrumental part of the team. Her work helped highlight the significance of the Fox Hills Sandstone formation specifically, as there are only three areas in Boulder County where this type of sandstone formation is exposed.

The sandstone, which is also called turtleback sandstone based on the polygons formed by the crust that resemble a turtle's shell, not only is a critical habitat for lichen and miner bees, but is also a unique remnant of a time when this area was a shallow inland sea. Several fossils including tiny sharks teeth and ophiomorph burrows-remnants of shrimp that once used the shoreline-have been found in the sandstone.

"Even though there's not a shrimp fossil, you can see the evidence of their life by seeing these fossilized excrement burrows," said Glowacki.

If you want to see any of these fossils, you will need to be part of a volunteer-led naturalist walk as this area is closed to the public, and collecting fossils on open space is a fineable offense. Groups interested in a naturalist-led walk can call Larry Colbenson at 303-678-6214 to schedule a geologist tour of this closed open space area.

"For all these reasons, we decided through our county process that we needed to close the area to the public, and that's why we put up the fences as well," said Glowacki.

There was initially a low log fence around the area and small signs asking visitors to please stay off the fragile sandstone habitat. But Glowacki noted that this didn't seem to be working as people were still walking, exercising and riding bikes on the sandstone.

"Fox Hills Sandstone is really fragile. If you ride a bike over it, you can disturb that top layer which erodes, and then it's gone for good and you can never get that layer back," she said.

When Boulder County Open Space personnel found that the low fence didn't seem to be keeping people from entering the area, they approached the NCA looking for solutions.

"So that's when we started conversations with the Niwot Community Association, and we took them on field trips and started talking about making this place off-limits so that we would not have any further deterioration of this rare geologic formation," Glowacki said.

"We also took it to our county commissioners and declared the area as closed. So really it's closed open space. If you're out there, you can get a ticket now," she said.

The fence was funded by Boulder County Parks & Open Space and built primarily by Boulder County Youth Corp leaders. The logs for the fence came from Boulder County's forestry project where logs from forest thinning are used to build fences to protect critical habitat.

Only time will tell if this new fence will more effectively keep visitors from venturing off the Niwot Loop Trail onto the closed open space. Glowacki noted that one way the community can help is to report trespassers or anyone who might be illegally collecting plants, animals, or fossils in the area.

"We are just asking the community to look out for the larger interests like preserving this rare geologic formation and all its lichens and animals and plants, and restrict ourselves from using the open space in a way that can damage it," Glowacki said.

"Open space has many values, and even just being able to look at it is often a value that we can appreciate without disturbing it in any way," she said.