Colorado Noxious Weed Advisory Committee (CNWAC) members from across the state came to the U.S. Department of Energy Office of Legacy Management’s (LM) the Rocky Flats Site, Colorado, near Denver on a partly cloudy June day. The committee saw a restored natural landscape where a small city once stood, thanks to revegetation and noxious weed management efforts.
CNWAC liaises with the Colorado Department of Agriculture, the citizens of Colorado, and other organizations. CNWAC gathers and synthesizes information and strategies related to vegetation control in public and private sites and then recommends action plans tailored to specific environments and situations.
Legacy Management Support Partner (LMSP) Ecologist Jody Nelson led the tour and knows the site well. He has supported Rocky Flats ecology activities for 30 years. After closure and cleanup of Rocky Flats Site in 2005, Nelson advised LM on the ecological management of the site and helped transition barren land into a thriving ecosystem. Today, Nelson and LMSP Ecologist Karin McShea support LM by managing the site’s natural resources.
During the tour, CNWAC members learned about LM’s ecological strategies that address challenges since site closure 19 years ago.
LM has a vegetation management plan for the Rocky Flats Site, which includes various options to control noxious weeds and future infestations while minimizing environmental damage and optimizing the use of available resources. For example, Nelson discussed the five biocontrols used to manage knapweed growth. A biocontrol is a living organism (often an insect) used to reduce the population of a weed species. Diffuse knapweed used to cover large areas of the site and is now much less prevalent. LM staff also recently found hairy willow-herb, another noxious weed, at the Rocky Flats Site, as well as at the Rocky Flats National Wildlife Refuge. LM and refuge staff are working together to manage it on both properties.
Nelson spoke proudly of a particularly interesting feature found at the site: xeric tallgrass prairie. This type of prairie is a very rare plant community. Considered a remnant from the last ice age, it’s found in a narrow band on mesa tops along Colorado’s Front Range.
The tour stopped at the forb nursery, where the site team seeded 30 to 40 different species of wildflowers that had been hand-collected on nearby open space properties by past volunteers. These wildflower seeds were given to the site to increase diversity in revegetation areas. Nelson noted that in the fall, the area abounds with white and yellow flowers.
The group also saw the Original Landfill and heard about the large underground anchors that were installed in 2020 to stabilize the hillside. The use of erosion control blankets, including coconut mat and turf reinforcement mat, along with compost filled wattles and wood straw, protects the ground surface from erosion while allowing the establishment of the seeded grasses. Products such as these are particularly useful since they tend to withstand the tramping hooves of large elk herds.