The Problem of Weeds on the Clackamas River

The Clackamas is a remarkably scenic river and a beautiful place to live, work, and recreate. The lower half of the river is home to many private residences, farms, public parks, quarries, golf courses, and natural areas. Unfortunately, and partly as a natural result of all this activity, it is also home to many invasive weeds.

Invasive weeds can cost landowners and managers a lot of money to control. They can degrade pastures and agricultural land. Some weeds can clog shorelines and smaller waterways, and some are even toxic. Furthermore, many of these weeds can spread upland or downstream, causing problems in other areas.

The CRISP hosted a 4-County Cooperative Weed Management Area field day, highlighting collaborative weed control and restoration along the Clackamas River. Photo by Samuel Leininger, CSWCD

Partner Collaboration

Many of our partners are doing great work along the Clackamas River. In particular, there has been a lot of work between Carver and Milo McIver State Park in Estacada. For example, the Clackamas River Basin Council has been removing weeds and planting native shrubs and trees at many streamside sites through their Shade Our Streams Program. Metro has many active restoration and weed control activities at multiple properties they manage. Both Oregon State Parks and Clackamas County also have multiple parks in this area where land managers control invasive weeds. The WeedWise program also controls high-priority weeds at many private and public sites along the Clackamas.

Despite all this great work, we needed shared strategies, increased coordination, and a way to seek sustainable sources of funding. The Clackamas River Invasive Species Partnership (CRISP) has provided these things, allowing us to accomplish more weed control. CRISP partners submit weed control project ideas and then meet to discuss and prioritize the projects. While we carry out projects throughout the whole watershed, the area between Carver and Milo McIver State Park is our key focus area. We highlight 3 focus area projects below.

Contracted crews spray false brome near Milo McIver State Park, Photo by Lindsey Karr, CSWCD

Milo McIver State Park (and surrounding areas) Project

Milo McIver State Park is an important area for both recreation and wildlife habitat. Aside from a few satellite weed patches, it also has the most upstream population of both garlic mustard and false brome. Because of its location on the River, and its importance as a recreation destination, it has a high potential to be a source for the spread of these weeds to other areas. For example, a camper, hiker, or disc golfer can come to the park from out of the area, get a bit of mud (with seeds!) on their boots or wheels, and then track it back home or to another park.

As a result of CRISP, Oregon Parks and Recreation Department has been able to go after these weeds more effectively and aggressively. Furthermore, the increased coordination has brought attention to the area and the WeedWise program has controlled these weeds on neighboring properties. Furthermore, the WeedWise program has been able to control two Oregon Class A noxious weeds, giant hogweed and oblong spurge, on neighboring properties. This prevents the weeds from entering the park, thus reducing the chances they will spread elsewhere.

Across the river, there is further collaboration to control several high priority weeds. Portland General Electric, Columbia Land Trust, the Clackamas River Basin Council, and the WeedWise program are working together to control garlic mustard, knotweed, policeman’s helmet, false brome, and spurge laurel.

Bohemian knotweed growing along Deep Creek. Photo by Clackamas River Basin Council

Knotweed Project

Originally from Asia, but introduced to Europe and North America in the 1800s, invasive knotweeds are aggressively invading streams, rivers, and other landscapes. Many people who live on the Clackamas or its tributaries are all too familiar with this weed. While all of the CRISP partners would love to completely eradicate it, there is simply too much for anyone to control at a large scale. The good news is that CRISP has increased both coordination and resources to allow us to control more knotweed than we could without the partnership.

In 2017, 2018, and 2019, after coordination with CRISP partners, the WeedWise team tackled knotweed along the Clackamas upstream from where Richardson Creek flows into the Clackamas (near the junction of Highway 224 and Tong Rd). The WeedWise program was also able to survey and treat knotweed along upper/middle Clear Creek, Eagle Creek, Dubois Creek, North Fork Deep Creek, and other smaller streams that flow into the Clackamas. The surveys are important for us to understand where the knotweed is coming from and how to prioritize our control efforts. We are also coordinating work with the Clackamas River Basin Council to control knotweed along Deep Creek. In the future, we hope to expand this work to other Clackamas tributaries and further downstream on the Clackamas.

Garlic mustard control on a property near the Clackamas River. Photo by Samuel Leininger, CSWCD

Garlic Mustard Project

Garlic mustard is another serious invasive plant in North America. Highly adaptable, garlic mustard is difficult to control, spreads through copious seed production, and forms dense stands that out-compete native vegetation. Eradicating garlic mustard is a long process that can take years, even decades, before eradication is even possible. Thankfully, garlic mustard has not spread along the Clackamas as badly as knotweed, and CRISP partners have been able to make control efforts at most of the known populations each year. Part of the problem we face is that we don’t know about all the garlic mustard patches or don’t have access to them.

CRISP has helped the WeedWise program to reach out to more property owners. We’ve sent letters to inform people about our program and our efforts to control invasive weeds. Currently, there are about 510 landowners in the Clackamas watershed that are signed on to participate. CRISP has also supported WeedWise efforts to survey those properties. In addition to these plant surveys, WeedWise and Metro collaborated to survey some of the islands in the Clackamas River. Afterward, we worked with restoration contractors to control the weeds we found, thus preventing them from spreading downstream.

Working Together to Control Weeds

The Clackamas River Invasive Species Partnership (CRISP) was formed to improve the management of invasive species within the Clackamas River watershed in northwestern Oregon. This partnership was initiated through the cooperative efforts of the Clackamas River Basin Council (CRBC) and the Clackamas Soil and Water Conservation District (CSWCD), with additional funding and support from Metro regional government.

Before the group’s formation, the Clackamas River Basin Council and the Clackamas Soil and Water Conservation District both had strong landowner assistance programs for control of priority invasive weeds and to restore riparian habitat in targeted areas of the watershed. Development of the CRISP has provided an opportunity to coordinate the efforts of these two organizations, as well as other partners across the Clackamas River watershed.

Developing a Plan

Bohemian knotweed growing along Deep Creek. Photo by Clackamas River Basin Council.

The first goal of the partnership was to identify current invasive species control efforts underway within the watershed. Tools such as online surveys and stakeholder meetings provided this information. Second, a Technical Advisory Group (TAG) of federal, state, regional, and local land managers convened to discuss existing efforts, long-term goals and outcomes, available resources, and management strategies. Information provided by the TAG served as the foundation for the development of the Clackamas River Invasive Species Management Plan, a comprehensive approach for managing invasive species within the watershed. The TAG meetings revealed strong support for invasive species planning among participants. During these meetings, TAG members broadly agreed to participate in ongoing planning and implementation efforts.  The partnership grew to include the 22 TAG members from 13 organizations.

In addition to the information provided by the TAG, a prioritization model known as the Weed Heuristics: Invasive Population Prioritization for Eradication Tool (WHIPPET), developed in California, was adapted for use within the Clackamas River watershed. The WHIPPET model helped prioritize infestations of 19 priority invasive species based on their potential impact, potential spread, and feasibility of control. Criteria related to specific populations, the ecology of the invasive species, and the quality of the area under threat, were all included in the WHIPPET model analysis.

Due to the size and complexity of the watershed, as well as resource scarcity, CRISP partners also sought to prioritize specific geographic areas for action. They  ranked sub-watersheds based on:

• data from the Intertwine Alliance’s Regional Conservation Strategy;
• existing partner participation; and
• rare, threatened, and endangered species.

The findings of this assessment were considered alongside additional factors including partner investments and engagement and resulted in the establishment of four priority areas within the Clackamas River watershed.

Partners created action plans for each of the four priority areas based on land use, the likelihood of invasive species introduction, survey and control needs, and restoration opportunities. These priority area action plans collectively form the Clackamas River Invasive Species Management Plan, which was completed in 2015. This plan outlines a clear and objective approach to managing invasive species in the Clackamas River watershed.

In 2016, the CRISP grew from its origin as an advisory group supporting the CRISP Management Plan development effort to a partnership. This transformation required the development of basic infrastructure to support the goals and activities of the partnership. The Memorandum of Understanding (MOU) outlines the partnership’s goals and structure and has now been signed by all partners. See the full CRISP MOU here. Since then, the partnership has grown to include 14 organizations.

To further enhance implementation efforts in the basin, the Clackamas SWCD also hired a specialist in December of 2016 to assist with the implementation of CRISP-related activities. The CRISP specialist supports activities between partners and manages many of the projects proposed by partners to cover gaps in management.

Funding the Plan

In order to implement the management plan, the CRISP sought funding to treat invasive weeds within the Clackamas River Basin. In 2016, the CRISP secured $431,250 in grant funding through Portland General Electric’s Clackamas River Hydroelectric Project Mitigation and Enhancement Fund to support implementation over the next five years. In 2020, CRISP received a second round of this funding for $258,192.

To support this grant, several CRISP partners also committed resources to the project. From 2016, through 2019, commitments have included $266,901 in cash and in-kind services from the Clackamas SWCD, $329,182 of in-kind services from Clackamas River Basin Council, and $445,084 in cash and in-kind services from Metro. CRISP partners have also applied for and received retained receipts funding from the Mt Hood National Forest for $51,500 in 2019, and $61,875 in 2020. Additionally, the BLM has awarded a partner agreement to Clackamas SWCD, thus contributing a total of $28,500 since 2016, and this is renewable each year pending available funding.  This BLM agreement is part of a larger funding pool that also includes weed control efforts in Sandy River Basin as well as administration of the Columbia Gorge CWMA and 4-County CWMAs. All of these funds allow the CRISP to do an immense amount of weed control in the Clackamas Basin.

Where are we now?

In 2017, CRISP partners developed a process for proposing and approving projects. Since then, partners have used this process to propose, discuss, prioritize, and carry out 49 projects totaling $359,258 in contractor services. For 2020, eight more projects have been proposed, with more to come later in the year.

Restoration contractors hand-pull garlic mustard in a floodplain area near the Clackamas River. Photo by Lindsey Karr, Clackamas SWCD

Several of these projects have involved invasive knotweed control. The Clackamas River Basin Council has been treating knotweed on Deep Creek since 2017. Because of CRISP support, they have been able to conduct more outreach and treatments each year, making a big difference in streamside habitat on Deep Creek. The Clackamas SWCD has also been treating knotweed on the Clackamas River and its tributaries upstream from Richardson Creek. Another project has focused largely on garlic mustard, a highly invasive weed. In 2019, the Clackamas SWCD was able to treat garlic mustard on 74 different properties. More details on these projects can be found on the Focus Area Weed Control Project Page.

Another large project has focused on the upper Clackamas watershed. The upper watershed contains 74% of the Clackamas watershed and is relatively pristine and undisturbed. Thus, small treatment actions there can make a huge difference in preventing the spread of weeds. CRISP has been surveying locations likely to contain weeds- places like trailheads, campgrounds, and rock quarries. Surveys have also focused on decommissioned roads, where weeds can pop up and then go unnoticed for many years. For more details on these surveys and the treatments that have followed, visit the Upper Watershed Project Page.

These projects and other CRISP partner activities benefit the Clackamas watershed by improving habitat, protecting many restoration planting projects, and preventing invasive weed problems for many landowners.  For detailed reports of CRISP projects, partner activities, funding, and expenditures, check out the annual reports since 2016 in the “Downloads” section below.

Many thanks to all of the CRISP partners, including:

• 4-County CWMA,
• Bureau of Land Management- Salem District,
• Clackamas County Parks,
• Clackamas County Water Environment Services,
• Clackamas River Basin Council,
• Clackamas Soil and Water Conservation District,
• Columbia Land Trust,
• Metro,
• Natural Resources Conservation Service- Clackamas,
• North Clackamas Parks and Recreation District,
• Oregon Department of Agriculture- Noxious Weed Program,
• Oregon Parks and Recreation Department,
• Portland General Electric,
• United States Forest Service- Mt Hood National Forest

Downloads:

• Clackamas River Invasive Species Management Plan

• Memorandum of Understanding

• 2016 Annual Report

• 2017 Annual Report

• 2018 Annual Report

• 2019 Annual Report

• 2020 Annual Report

• 2021 Annual Report

• 2022 Annual Report

For more information about the Clackamas River Invasive Species Partnership, contact:

Samuel Leininger

WeedWise Program Manager

Clackamas Soil and Water Conservation District

[email protected]

503-210-6006

OR

Monte Mattsson

WeedWise Specialist- CRISP

Clackamas Soil and Water Conservation District

[email protected]

503-210-6018

The WeedWise Program is dedicated to helping protect Clackamas County from the ongoing threat of invasive weeds.  These projects are often based around the prevention or management or priority invasive weeds. We currently working on projects across the county, but focus largely on priority invasive weeds, priority sites, or on partnership projects.

Priority Weed Control Projects

Orange hawkweed control is an example of a priority weed control project underway at several locations in Clackamas County.

The priority weed control program focuses on the Early Detection and Rapid Response (EDRR) of new or rare invasive weeds where the goal is either eradication or containment.  These projects allow us to focus our resources for maximum impact.  Priority weed control projects typically occur at the landscape level and impact multiple landowners either public or private.  These project focus on the control and eradication of a priority weed species.  Some examples of our current priority weed control projects include the active management of:

• Garlic mustard (Alliaria petiolata)
• False brome (Brachypodium sylvaticum)
• Spurge laurel (Daphne laureola)
• Oblong spurge (Euphorbia oblongata)
• Japanese, Giant, and Bohemian knotweed (Fallopia japonica, F. sachalinensis, and F. x bohemica)
• Goatsrue (Galega officinalis)
• Orange hawkweed (Hieracium aurantiacum)
• Giant hogweed (Heracleum mantegazzianum)
• Policeman’s helmet (Impatiens glandulifera)
• Blessed Milk Thistle (Silybum marianum)
• Puncturevine (Tribulus terrestris)
• Gorse (Ulex europaeus)

The priority weed control projects are one of our highest priorities and target all known infestations across the county or within a given management area.

Priority Site Projects

The Bull Run Gate Project was initiated to protect the city of Portland’s municipal watershed from encroaching birds dispersed invasive weeds

Priority site projects are projects that are designed to protect areas of exceptional quality or of unique ecological, economic, or cultural importance.   Some examples of projects that the WeedWise program is currently working on or have spearheaded in the past include:

• Barton Area Priority weeds project
• Bull Run Gate weed control project
• Coral Creek weed control project
• Molalla River confluence project
• Newell Creek restoration project
• Salmon River priority weed control project
• South Creek-Abernethy project
• Lolo Pass priority weed control project

The priority site project areas are typically local or regional significance and are designed to protect or buffer these areas from  the encroachment or spread of invasive weeds.  The goals of these projects is typically focused on exclusion and maintenance of natural areas within the project areas.

Partnership Projects

Knotweed control efforts undertaken in conjunction with the Clackamas River Invasive Species Partnership, focus area project.

Partnership project are those projects that are typically undertaken in conjunction with local and regional partners.  These projects are often complex and have diverse interests.  These projects involve working in cooperation with partner organizations to implement projects across broad geographic areas or across jurisdictional boundaries.  Examples of partnership projects include:

• The Backyard Habitat Certification Program Clackamas County Expansion
• The Clackamas River Invasive Species Partnership Upper Clackamas Surveys
• The Clackamas River Invasive Species Partnership Focus Area weed control project
• The Portland Metro Garlic mustard working group
• The Mt Hood National Forest Working Group
• The Sandy Basin Vegetation Restoration Coalition priority weed control

Learn More

To learn more about our projects please check the project drop downs in the navigation menu above, or contact us about information pertaining to a particular project mentioned.