River canyon
  1. Home
  2. Documents
  3. Programs
  4. Projects
  5. Watersheds
  6. About Us
User Menu Search

Hybrid Knotweed Mapping

The District encompasses many tributaries to the Snake, Salmon, and Clearwater Rivers. Through resource inventories and public meeting processes the District identified weed control as one of its top five priorities in order to achieve riparian restoration and protect stream health.

Steelhead were listed as threatened on the Endangered Species list in 1997. Steelhead habitat in the Lapwai Creek watershed is limited by lack of in stream structure, high water temperatures, low summer flows, and sediment.

The 2003-2007 field season data indicated a lack of riparian vegetation was contributing to the habitat limitations. These limitations include; poor in stream cover (from lack of woody debris), high water temperatures (lack of vegetation to provide shade), low summer flows (low organic matter in banks to store water) and sediment (lack of root mass in stream banks to prevent erosion). Weeds are a major concern in the ability to establish riparian vegetation. One of the weeds identified is hybrid knotweed (Polygonum cuspidatum).

The District completed a hybrid knotweed control demonstration project in 2004. The demonstration project was developed to identify treatment methods and educate landowners. The demonstration project results were used to develop a District-wide hybrid knotweed treatment strategy. Knotweed mapping is a component of this strategy. Funding for the completion of this plan was obtained from the District’s general operating funds and the Bonneville Power Administration’s Columbia Basin Fish & Wildlife Program for project # 2002-070-00.


  1. Identify areas containing knotweed.
  2. Prioritize control areas.
  3. Schedule and implement treatment

The District’s long-term goals are to inventory the entire District. Due to labor shortages the District prioritized areas for inventory. The priority is based on 1) current watershed inventory activities, 2) current watershed implementation plans and 3) areas identified with infestations during public listening sessions and field observations of District and other agency staff and ease of access.

Priorities are identified in the Hybrid Knotweed Control Plan. Lapwai Creek is the number one priority. The mapping in Lapwai Creek has been completed on lower Sweetwater, Mission, Garden Gulch and Tom Beall tributaries. Approximately 50% of the inventory work is completed on mainstem Lapwai Creek.

Lapwai Creek Hybrid Knotweed Control Plan - 2011


Nez Perce Soil and Water Conservation District
27880 Chambers Road
Culdesac, ID 83524

Mailing Address:
P.O. Box 131
Culdesac, ID 83524

Contact Us

Phone:  208-843-2931

Fax:  208-843-2234


Terms Of UsePrivacy StatementCopyright 2024 by Nez Perce County
Back To Top