A changing changing climate in the Pacific Northwest will challenge the Willamette River watershed. The river is lined with cities and towns that are home to more than two-thirds of Oregon’s 3.8 million residents, and the valley’s population is expected to double by 2050, bringing additional stress to a system that has already seen more than 160 years of land-use change.
The river that provided food and transportation to native people for more than 9,000 years and helped to propel Euro-American settlers in the 1800s has undergone a transformation:
• Less than 40 percent of the river’s length is forested today, compared to 87 percent in 1850. Length of river channels in the mainstem has decreased by 25 percent, and wetlands throughout the valley have decreased 95 percent.
• Cities, industries and farms withdraw an average of more than 37,000 cubic feet of water every day from the Willamette. More than 80 miles of small tributary streams that historically flowed year-round now go dry in a moderately dry summer.
• The Willamette basin supports 35 native fish species but now contains an additional 31 non-native species.
• The Pacific Northwest’s climate is uncertain. Air surface temperatures are projected to increase by 0.2-1°F per decade, and precipitation timing and amounts may change, potentially leading to larger water withdrawals and increasing stress on some fish species.
While these trends seem dire, I and many other scientists have a vision of a restored, more resilient Willamette River. The rich and complex river channels witnessed by Lewis and Clark and other explorers in this region will not return, but rather, through deliberate design, we can see a more ecologically sound and livable future in the valley.
Getting there will require solid information about the distributions and habitats of native aquatic species, cold-water refuges, floodplain-inundation extents and opportunities for river and floodplain restoration. Researchers at Oregon State University, the University of Oregon, the Oregon Department of Fish and Wildlife and other agencies are providing the basis for the future.
Meanwhile, restoration initiatives are already under way. The Special Investments Partnership of the Oregon Watershed Enhancement Board and the Willamette River Initiative of the Meyer Memorial Trust have partnered to conserve and restore floodplain forests and channel complexity in the Willamette River mainstem. State and federal agencies are conserving habitats and restoring altered habitats in response to the Willamette River Biological Opinion, Wildlife Mitigation Agreement and other programs. Watershed councils are addressing ecological conditions along the mainstem and the smaller tributaries where their previous efforts have focused. The Willamette Partnership and Clean Water Services have developed systems for carbon-credit and thermal-credit trading that could involve reforestation of riparian areas and floodplains. Cities and industries are exploring options to mitigate for thermal effects of water use and treatment practices. A diverse array of citizens’ groups, ranging from farmers to urban residents to industrial coalitions, are developing grass-roots programs to identify conservation opportunities and find ways to make them happen.
These programs build hope that the trends in resource loss observed in the Willamette River over the last 160 years may be reversed. The decisions we make today in our communities will shape the future of the Willamette River and the cities, farms and forests that depend on this river of change.