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Marion Soil & Water Conservation District

Invasive Plant Survey

The staff at the Marion Soil and Water Conservation District (District), with approval from the Board of Directors, created a Weed Inventory Program in 2008. Our goals for the invasive plant survey program are to: create and prioritize education, control, and restoration efforts for invasive species that are found along the waterways, and to assist landowners with reducing/controlling/eradicating invasive weeds on their property by offering identification assistance and advice on best management practices for controlling invasive species. This project is a partnership between the District, US Forest Service-Willamette National Forest, Oregon Department of Forestry, North Santiam Watershed Council, Mid-Willamette Cooperative Weed Management Area, Marion County Weed Control District, Bureau of Land Management and Cascade Pacific Resource Conservation and Development Area, Inc.

Plant Surveys

2011 Survey: Zollner & Bochsler Creeks and a portion of the Pudding River

In 2011, Invasive weed surveys were conducted along the banks of Zollner and Bochsler Creeks and a portion of the Pudding River between Zollner Creek and the Little Pudding River in Marion County during July and August. The goal of this survey was to record all the Marion County Weed Board Listed plant species that occurred throughout the riparian sections of the survey area.

The survey crew found only 4 species from the weed list along approximately 30 miles of water way. Weed occurrences were spread throughout the entire survey area; however species distributions differed within the survey area. Numerous occurrences of tansy ragwort (Senecio jacobea) were found throughout the survey area and a significant infestation of yellow toadflax (Linaria vulgaris) was found along the Pudding River. Also found were dense areas of Traveler's Joy/Old Man's Beard (Clematis vitalba) along the Pudding River between Zollner Creek and the Little Pudding River, and one location of yellow flag iris (Iris pseudacorus) on an upper branch of Zollner Creek.

This area is predominantly agricultural land with cultivated fields, many nurseries, and some livestock grazing. Weed locations were almost entirely found on the field edges between the cultivated areas and the riparian vegetation. It is important that these infestations are controlled and managed, because agricultural practices can aid in the spread and transport of invasive plant species to other locations within the watershed, within Marion County, and beyond.

2010 Survey: North Santiam and Santiam Rivers

The Marion Soil and Water Conservation District (SWCD) has completed the Invasive Plant Survey along the banks of the North Santiam and Santiam Rivers in Marion County. The surveys began west of the Stayton city limits and ended at the Willamette River. The lower portions of selected tributaries were also surveyed, including: Cold Creek, Sidney Ditch, Morgan Creek, Jefferson Ditch, Marion Creek, Talbot Slough, Edgar Slough and Logan Slough. The surveys included both public and private lands, and crews surveyed for 4 weeks: 2 weeks each in June and July.

The survey crew found a total of 8 species from the weed list along a 27 mile stretch of river, and the lower portions of 8 tributaries. Weed occurrences were spread throughout the entire survey area; however species distributions differed within the survey area. Numerous occurrences of knotweed were found throughout the survey area, mainly in 3 large concentrations. False brome was more prevalent in the upper section of the survey area near Stayton. The lower section of the survey area is less populated and less accessible than the upper section. We believe that the limited access prevented the spread and transport of invasive species to some downstream locations. In areas where there was direct access to the river, there were significantly greater concentrations of invasive species.

2009 Survey: North Santiam River

The Marion Soil and Water Conservation District conducted an Invasive Species Survey on public and private property along the North Santiam River in the summer of 2009. The surveys began at Whitewater Creek above Idanha, and continued through the Stayton city limits. The goal of this survey was to record all the Marion County Weed Board Listed weed species that occurred throughout the riparian section of the river.

The survey crew found 8 species from the weed list along a 53 mile stretch of the North Santiam River and the lower portions of 27 tributaries. There was a greater concentration of weed occurrences in the lower stretches of the survey area from Gates downstream to Stayton than in the upper portion of the survey above Big Cliff and Detroit Dams. The lower section of the survey area is more populated than the upper section and is associated with increased recreational use and access. This increase in activity leads to the increased spread and transport of invasive species. Future projects include working with private landowners and federal, state, and county personnel to develop control and restoration plans.

2008 Survey: Little North Santiam River

The first weed inventory was conducted along the banks of the Little North Santiam River in August and September 2008. The goal of this survey was to record all the Marion County Weed Board Listed weed species that occurred throughout the visual riparian sections of the river.

The survey crew found a total of 7 species from the weed list along a 25 mile stretch of river. There was a greater concentration of weed species in the lower section of the river near the confluence with the North Santiam River and the town of Lyons, than in the upper and middle sections of the river. These areas downstream are associated with increased recreational use and access, and have a greater population base. Future projects include working with private landowners and federal, state, and county personnel to develop control and restoration plans.