By definition, invasive weeds pose a threat whenever they occur, but some of these weeds can be more damaging than others.  As a result, invasive weeds are prioritized based on their relative risk, negative impact, and the potential return on investment.  Below are the rankings and classifications for various listing entities in our region.

WeedWise Classification

Priority:  These weeds are the highest priority and are actively being targeted for eradication by the WeedWise Program.  Landowners are encouraged to notify the WeedWise program for assistance with these weeds and to actively control them on their property.

Containment:  These weeds are a priority for management.  In some areas, these weeds are so widespread that treatments are not feasible in all locations.  For these weeds, infestations will be targeted for eradication when they occur outside of established containment areas.  For infestations within containment areas, landowners are encouraged to contact the WeedWise program for technical assistance in developing plans to improve the management of these invasive weeds.

Maintenance:  These weeds are damaging and widespread.  The WeedWise Program encourages control by landowners and can assist with the development of a plan to control these weeds.

No designation:  Some weeds listed below have no designation.  This is because the listed weed is either not a state-listed noxious weed or because it is not known to occur in or near Clackamas County.

Oregon Noxious Weed Classification

Class A – a weed of known economic importance which occurs in the state in small enough infestations to make eradication or containment possible; or is not known to occur, but its presence in neighboring states make future occurrence in Oregon seem imminent.  Recommended action: Infestations are subject to eradication or intensive control when and where found.
Class B – a weed of economic importance which is regionally abundant, but which may have limited distribution in some counties. Recommended action: Limited to intensive control at the state, county or regional level as determined on a site specific, case-by-case basis. Where implementation of a fully integrated statewide management plan is not feasible, biological control (when available) shall be the primary control method.
Class T – a priority noxious weed designated by the Oregon State Weed Board as a target for which the ODA will develop and implement a statewide management plan. “T” designated noxious weeds are species selected from either the “A” or “B” list[/quote]

Washington Noxious Weed Classification

Class A noxious weeds are usually newcomers. They are often found in only a few places in the state, and state and local weed boards hope to completely eradicate them before they get a foothold in Washington. Class A weeds are the ones you are least likely to see – but the ones that are most important to report. (If you see a plant you think might be a Class A noxious weed, please report it to your County Weed Board.)

Class B noxious weeds are abundant in some areas of the state, but absent or rare in others. The goal for Class B weeds is to control and reduce their occurrence where they are abundant, and to prevent them from spreading to those parts of the state where they are rare or absent.

Class C Noxious weeds are already widespread in Washington. In some cases, counties may require property owners to control Class C weeds, but more often counties simply try to educate residents about why controlling them is a good idea.

4-County Cooperative Weed Management Area Weed Classification

A = red alert, most invasive, still controllable on a regional or local scale or limited spread
B = most invasive, locally abundant
C = most invasive, widespread
D = less aggressive, wildland invaders, less impact on natural systems
E = aggressive primarily in horticultural/agricultural situations;  note: this category is incomplete
F= needs more info, should be noted if and where it’s a problem
W= watch list

Columbia Gorge CWMA Ranking:

‘A’ Listed Weeds: Early Detection.  Some of these weeds are found outside the CWMA region but could invade the region at any time in the future.  Some have been found in the CWMA in isolated populations.  Management focuses on developing an Early Detection Rapid Response (EDRR) network of people and organizations to identify sites.

‘B’ Listed Weeds: High Importance.  These weeds can be locally abundant, but may also occur in spotty distribution across the landscape.  Management focuses on inventory to determine distribution, followed by eradication of small, isolated populations, and control or containment of larger infestations.

‘C’ Listed Weeds: Common.  These weeds occur across the landscape at a level where eradication, containment or control is not economically feasible.  Management focuses on removing them from ecologically, socially and economically important sites and slowing their spread through prevention actions.  When available, biological controls should be used.

‘W’ Listed Weeds: Watch list.  These weeds display invasive qualities in our area or similar ecosystems, but they have not yet proven to be problematic. Management focuses on inventory to determine if the plant is behaving aggressively followed by eradication or close observation going into the future. The purpose of the “Watch list” is to gather more information on suspect weeds, as well as monitor for occurrence or spread. Information collected may be used to justify future inclusion on the state


WeedWise Program