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The Western Muddy Creek watershed is located on the East side of Oregon's Coast Range mountains, just Southwest of Corvallis, OR and Northwest of Monroe, OR.
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Elevations within the watershed range from approximately 200 feet above sea level in the Northeast corner, to about 2,000 feet at the Western-most crest. | ||
Average annual rainfall is 40-60 inches, but significant periodic flooding does occur. As a result of the Bretz Floods, the melting of Pleistocene ice sheets in Montana that consequently drained and funneled down the Columbia Gorge, a portion of the water was deflected up the Willamette Valley to form a short-lived lake that deposited silt on the flood plains of the rivers and streams within the valley. Despite the retreat of this glacial lake, the Willamette Valley is still dominated by characteristic features created by flowing water. While the Willamette River, now predominantly channelized, once meandered across the broad, flat, alluvial valley floor, its' route can still generally be seen in its remnant terrace deposits, slough, islands, meander scars, oxbow lakes and yazoos. The main stem of the Muddy, a yazoo, is an example of one of the Willamette's pervious courses, remnant of it's once meandering nature that allowed it to cross the valley's floor. |
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Christmas tree plantations occur extensively in the midlands.
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| The upper elevation lands are mostly managed for timber production (the mill town of Dawson is show to the right). |  | ||
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The 5,325 acre (2,155 hectare) Finley National Wildlife Refuge is located in the central eastern portion of the watershed. The reserve hosts an abundance of wildlife, although its primary mission is the protection and management of wintering habitat for dusky Canada geese. | ||
| Currently approximately 3000 residents live within the watershed. Housing is primarily low-density "rural residential" with typical lot sizes ranging from 2-5 acres. Most houses are dependent on well water and have septic systems. |
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Within the framework of Oregon's landuse planning system, the watershed is primarily in "Exclusive Farm Use" (shown in tan - 42%), "Primary Forest" (shown in dark green - 35%) and "Secondary Forest" (shown in light green - 13%). The Finley National Wildlife Refuge (shown in blue - 7%) and Rural Residential Zoning (pink - 3%) make up most of the remainder. There is one small community, Alpine, located in the Southern portion of the watershed and zoned as "Rural Residential." There is also extensive single-family housing in the Northern portion of the watershed which predates the current zoning. | ||
| A Detailed Multimedia Database of 1990 Conditions is available, including our Full 1996 Photo Archive. Quicktime Panoramic Photography fans will want to try out our Map of VR Photopoints. |
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The vegetative cover represented in the 1850 landscape differs significantly from the landscape of today. Vegetative species associations in the present landscape are less complex than those of past. For example, the forests of the present are less diverse in their species mix than in the mid-19th century and cover a greater percentage of the watershed. Changes in the use of land and in the management of natural and human systems are responsible for these differences.
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Prior to Euro-American settlement the practice of burning and extensive flooding were determining factors for vegetative communities in the Willamette Valley. Wet and dry prairie, Oak savanna, and "thinly timbered woodland" covered more than half of the Western Muddy Creek watershed in the valley bottoms and lower slopes of the Coast Range mountains. Native Americans set fires in the dry season which ranged over large areas and had the effect of driving and concentrating game and maintaining grasslands for food gathering of staples such as camas root and acorns. The annual or biannual fires in the bottomlands had the effect of killing shrub and tree seedlings except in the wettest areas along perennial streams or in low-lying swales. Flooding was frequent and the rivers and streams consisted of multiple meandering channels.
The Western Muddy Creek watershed was largely comprised of wet and dry prairie along the eastern half in the lower elevations, Douglas Fir-Western Hemlock forest in the higher elevation foothills of the Coast Range mountains along the western edge, and White Oak savanna interspersed throughout the prairie and bordering forestlands. "Thinly-timbered forests" Riparian forest and swamps abounded along the stream channels and in low-lying areas with saturated soils.
| Alpine Near the Turn of the Century |
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Prairie communities were variously made up of plants adapted to wet or moist conditions all year which tended to be in the low-lying valley bottomland and swales, or dry prairie plants adapted to seasonal patterns of winter rains and summer drought. Many of the perennial streams flowing from the forested uplands disappeared into the sandy floodplain soils, reappearing in channels closer to the Willamette River, feeding the larger streams through groundwater.
In some areas, particularly along the margins of the valley, fire-resistant oaks or other large trees were able to survive the low-intensity fires. These areas were characterized by savanna vegetation, with three variations of dominant trees surrounded by an open understory. The first dominant tree type was White Oak, the second was White Oak and Douglas Fir, and the third was White Oak and Ponderosa Pine. The understory throughout the scattering of large trees consisted of grasses and herbaceous plants which varied in composition in response to soil moisture.
Forests occupied the higher elevations and were also influenced to a lesser extent by naturally-occuring fires, particularly in the drier south-facing slopes and ridgetops. The predominately Douglas Fir-Western Hemlock forest included Western Redcedar and some Bigleaf Maple, with Red Alder in riparian corridors and the slow-growing Pacific Yew in the understory. Forests under 1,000ft in elevation included Grand Fir in the mix. The more xeric areas (south slopes and ridge tops) tended towards a thick understory dominated by Chinquapin and Madrone. Forested areas in lower elevations bordering the prairie tended to include a mix of White Oak, Incense Cedar as well as Grand Fir, Western Redcedar and Pacific Yew.
Thinly timbered forests with an open canopy were dominated by Douglas Fir or a mixture of Douglas Fir and White Oak. These woodlands occupied the border between forest and praire-savanna lands. Unlike the relatively open grassy or herbaceous understory of the White Oak-Doug Fir savannas, the understory was thick with shrubs and were designated as nearly impassable by the surveyors. Western Hazel, Bracken, Oak sprouts and other shrubs created the brushy understory of these woodlands.
Unfortunately, contiguous historic airphoto coverage of the watershed was not available. We did find several scenes of smaller areas within the watershed going back far as 1936.
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| Mainstem of Muddy 1936 |
Locating and identifying historic landscape photography of the area proved similarly challenging. Staff at the Finley National Wildlife Refuge generously shared the limited imagery they have available, but these images are very grainy and low in contrast. We found two images of Alpine in the University of Oregon's library, as well as a variety of images from outside of the watershed showing common land use practices.
The process of developing characterizations of past and current conditions was not merely a technical exercise in map making. Rather, the GIS database was an evolving model of which land characteristics were considered to be important by the group as a whole. In this sense, the more important process was that of agreeing on a common language, in the form of a categorization of land use and land cover. The land use / land cover maps were the major form in which stakeholder understandings about the place in which they live were passed on to technical experts in biodiversity and water quality.
Significant benefits resulted from including the stakeholder group in the process of GIS development. It not only resulted in more accurate mapping, it built a common understanding about the watershed for all parties. While maps are a useful abstraction, effective communication using maps requires a shared knowlege base.
These data layers are provided as GIF images and in macGIS and ERDAS map format. They are all derived from 1:24,000 scale maps or better and are in the UTM Zone 10 projection. To examine these themes further, click on the previews below. Full coverages for the 1850 and 1990 landuse/landcover maps are available in thethird section, Envisioning the Future
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