Rocky Flats has evolved from being a producer of plutonium for nuclear weapons to becoming a refuge for wildlife.

After Rockwell, the company that operated the Rocky Flats plant, pleaded guilty to criminal violations, the plant was shut down in 1992.

During the massive cleanup, over 800 structures were demolished and many tons of contaminated material were removed. In 2001 the 5,237-acre Rocky Flats Wildlife Refuge was established while the cleanup — which did not end until 2005 — was still ongoing.

Because we were concerned about the safety of the site for users as well as the effect of recreation on wildlife, we and many others lobbied for a trail circling the perimeter of the refuge instead of cutting through it. However, in 2018 several trails through the former security buffer zone were open to the public after the zone was declared safe by the Department of Energy. DOE continues to monitor Rocky Flats for safety, and the center portion is a superfund site closed to the public. It’s a contentious issue as many scientists say any part of the site is unsafe.

Although we continue to avoid the former buffer zone and the superfund site, we think trails on the periphery of the refuge pose little danger to hikers who stay in the area for short periods of time. On the other hand, many people think any activity here could be harmful. Caveat emptor.

After years of avoiding the place, we finally decided to walk the 1.4-mile Walnut Creek Loop, located on the far northeast edge of the refuge. If you go, stop at the kiosk for a brochure and map. As we headed west from the trailhead off Highway 128 we enjoyed the expansive blue sky, the wind-swept grassland, and superb mountain views stretching from Longs Peak to Pikes Peak. The windmill farm and the National Center for Atmospheric Research are visible in the distance. Walnut Creek, which lies in the draw below the trail, is typically dry, and in early March the landscape was mostly brown with not even a filaree yet in bloom.

Last year we watched two golden eagles on a power tower, but this year we failed to spot even a red-tailed hawk or prairie falcon. Nor did we see any coyotes, deer, fox, or elk that all live in the refuge. That’s just luck of the draw when you go for a hike. The NWR brochure says more than 630 plant species and more than 239 wildlife species inhabit the refuge including the rare Preble’s meadow jumping mouse.

At the far end of the loop there’s a junction with the Rocky Mountain Greenway Trail. If you turn right onto this trail it leads south to the historic Lindsay Ranch. The Rocky Mountain Greenway Trail will eventually connect Rocky Mountain Arsenal, Two Ponds, and Rocky Flats National Wildlife Refuges. This section of the trail comes a little too close to the Department of Energy Legacy Site for our comfort, so we have not hiked it.

When we visited the Woman Creek drainage section of Rocky Flats in 1996 with the Colorado Native Plant Society, we were impressed by the many wildflowers and by the xeric tallgrass prairie that thrives in the clay and cobble loam. So we were disappointed to find mostly non-native smooth brome with a few patches of little bluestem and blue grama grasses along the Walnut Creek Loop that lies on a high plateau instead of in a valley bottom. Maybe we’ll explore the Woman Creek Trail starting on Highway 72 next time.

Directions: Drive south on Highway 93 to Highway 128 and turn east. The trailhead sign is 3.3 miles from the intersection on the right.

Ruth Carol and Glenn Cushman are the authors of “Boulder Hiking Trails,” available on Amazon.