The top 3 priority weeds: Tall whitetop (Lepidium latifolium), Giant reed (Arundo donax), and Tamarisk (Tamarix ramosissima)

Much of the plant life that you find in the Wash today is not native to the area. As of the year 2000, an estimated 80% of the vegetation in the Las Vegas Wash was tamarisk (Tamarix ramosissima), an invasive plant listed on the state noxious weed list. In 2001, tall whitetop (Lepidium latifolium), also listed on the state noxious weed list, was first identified in the Wash mitigation areas and was soon discovered throughout the Lower Las Vegas Wash area.

In total, more than 1,500 acres of invasive weeds have been documented at the Wash. To address this growing weed problem, the multi-agency Las Vegas Wash Weed Partnership (Partnership) has spearheaded an aggressive weed control program on the Wash. Since 2002, the National Park Service Exotic Plant Management Team with assistance from Clark County Vector Control has biannually surveyed fourteen linear miles along the Wash for weeds. Surveys consist of both on-the-ground and aerial observations and are combined with treatment to increase crew effectiveness. All sites are documented using GPS technology and maps are created.

Just some of the plants targeted by the Partnership include: tamarisk (Tamarix ramosissima), tall whitetop (Lepidium latifolium), giant reed (Arundo donax) , green fountain grass (Pennisetum setaceum cupreum) and Russian knapweed (Centaurea repens). Since the inception of the weed management program, 680 gross infested acres of tall whitetop have been treated, 200 acres of tamarisk have been cleared, 38 stands of giant reed have been removed and an additional 1/4 acre of giant reed is being monitored for resprouts post treatment and the only known population of Russian knapweed has been eradicated from the Wash. To help dispose of cut material from the weed management program; five controlled burns have been conducted at the Wash saving hundreds of thousands of dollars in disposal costs.

Community awareness is essential to the success of this program and several documents and outreach materials have been developed to educate the public about weeds and encourage their involvement at the Wash. Several volunteer weed pulls have been hosted at the Wash, a fact sheet entitled, Weeds: Pretty Plants Gone Bad, has been created and the Wash was the showcase in the educational DVD for the Clark County School District, Las Vegas Centennial Celebration Education Grant Celebrates the History and Importance of the Las Vegas Wash, produced through the Clark County Cooperative Weed Management Area.

Funding for the project has been provided by the National Fish and Wildlife Foundation, Clark County Multiple Species Habitat Conservation Plan, U.S. Bureau of Reclamation, National Park Service, Nevada Department of Environmental Protection and Southern Nevada Public Land Management Act.

Background

Managing invasive weeds is a vital part of the overall stabilization and enhancement of the Las Vegas Wash (Wash). Compliance with the Corps' Section 404 permit requires that the SNWA maintain an 80% survival rate of native species and less than 20% cover of invasive plant species. To improve the progress of compliance and maximize the effectiveness of the revegetation program in the Wash, the SNWA formulated the Las Vegas Wash Weed Partnership in 2002, with the assistance of grant funds from the National Fish and Wildlife Foundation. The mission of the Partnership was "to promote awareness among the landowners and land managers within the hydrographic basin, facilitate cooperation and collaboration, create an integrated weed management plan, and implement on-the-ground weed management activities in the lower Las Vegas Wash." By September 2003, the final "Integrated Weed Management Plan for the Lower Las Vegas Wash" document was completed. The document outlined the Partnerships future activities and methods for accomplishing goals that support revegetation at the Wash. Within the document the weeds that were identified by the Partnership as potential concerns included tall whitetop, giant reed and saltcedar. The ongoing activities to reduce these invasive weeds have been crucial in the overall revegetation program.