Click on the links below for background information about the Willamette Water 2100 project.

Shaded relief map of the Willamette River Basin, looking to the west and the Pacific Ocean.  Image credit: Charles Preppernau, OSU.  Photo credits (left to right): USACE, OSU, OSU.

Project Overview

The Willamette River Basin in western Oregon spans nearly 12,000 square miles (30,000 square kilometers), from its snowy, forested headwaters in the Oregon Cascades to its green valley floor. It is home to 70% of Oregon’s population, and provides water for the region's diverse ecosystems and economy. Currently, the Willamette River Basin is water-rich, but with a warming climate and increasing socio-economic pressures that may not always be the case. Such pressures raise a number of important questions:

  • Will we have enough water to satisfy future needs?

  • Where, when and under what conditions might water scarcity emerge in the coming decades?

  • What policy actions might reduce the potential for water scarcity?

These questions motivated the Willamette Water 2100 project (WW2100), a collaborative research project led by faculty from Oregon State University (OSU), the University of Oregon (UO), Portland State University (PSU) and the University of California-Santa Barbara. The project was funded by the National Science Foundation and the National Oceanic and Atmospheric Administration and ran from October 2010 through September 2016.

Project Purpose

The primary project objectives were to:

  • identify and quantify the linkages and feedbacks among human, hydrologic, and ecologic dimensions of the water system,

  • make projections about where and when human activities and climate change will impact future water scarcities,

  • evaluate how biophysical and human system uncertainties affect these projections, and 

  • evaluate how policy changes or other interventions might affect future water scarcities.

We recognize that the Willamette River Basin is a complex coupled system, one that includes both a natural system (the biophysical components) and a human system (the socio-economic components). The interactions, feedbacks, and evolving characteristics of these different components will control when and where water is abundant or scarce. Modeling such a system has to be selective: it would be impossible to model all aspects of such a complex system in great detail and high resolution. We therefore chose to focus on the elements, relationships, and feedback mechanisms that were most important to the key objectives described above. Fig. 1 describes at a general level the main components of the Willamette River Basin that we modeled in detail. The components include “external drivers” (factors outside the control of people in the basin), including the climate, population growth, and growth in income levels. This conceptual model identifies components related primarily to water supply and demand. Water supply is mainly determined by the biophysical system. Water demand includes human demands for water that are both direct (urban use) and indirect (water allocated by law to protect fish). At a general level, human decisions influence how land and water is used as a result of laws, regulations, and policies, and these in turn influence how individual decisions are made (farmers, consumers), and how society’s representatives (public officials) act to allocate land and water (e.g., reservoir management).

Conceptual diagram of Willamette Envision and its modeling components.

Figure 1. Conceptual diagram of the Willamette water system showing the human and natural system elements that Willamette Envision represents.

Given the complexity of the system, and the detailed spatial and temporal scales at which these different components interact and influence each other, an explicit and quantitative representation of this system requires a computer model to incorporate the many processes and relationships in time and space between and among the natural and human system components, so that we are able to predict how those processes are likely to change over time. As a result, we developed Willamette Envision, a computer model that includes sub-models for each of the biophysical and economic components indicated in Fig. 1. The model captures key biophysical and socioeconomic elements of the system that allow us to address the first two objectives. In addition, the model can be used to ask “What if?” questions of interest to applied scientists, policymakers, and the general public. These questions explore the interactions between land and water use, law and policy, and public management of land and water resources. A more detailed description of Willamette Envision is contained in the model overview section.

Website Purpose

As a companion to the project’s scientific publications, this website provides an overview of project methods and findings, and a portal to access publications, data products, and unpublished project materials. It also contains sections describing the project’s broader impacts activities such as engagement with regional stakeholders, and training provided to university students and K-12 students and teachers. This website is intended for use by scientists, water and land managers, policy and decision makers, and educators.


Project Setting

The Willamette River flows north, draining 29,728 square kilometers (11,478 square miles) of diverse landforms and ecology. To the east, High Cascades volcanoes create the basin’s headwaters, with alpine peaks ranging up to 3,426 meters (11,239 feet). To the west, weathered volcanic and sedimentary rocks of the Coast Range bound the basin. Coniferous forests predominate in both mountain ranges and cover about 70% of the basin. Agriculture and city landscapes predominate in the Willamette Valley, with many cities including Eugene, Salem, and Portland clustered along the Willamette River mainstem. The basin’s river systems are home to diverse aquatic species including 36 native fish species, seven of which are listed by the federal or state government as species of concern.

Shaded relief map of the Willamette River Basin, looking to the west and the Pacific Ocean.  Map credit: Charles Preppernau, OSU.  Photo credits (left to right): Al Levno, USFS; OSU; USACE.

Figure 1. Shaded relief map of the Willamette River Basin, looking to the west and the Pacific Ocean. Image credit: Charles Preppernau, OSU. Photo credits (left to right): Al Levno, OSU, USACE.

Water in the Willamette Basin

Seasonal patterns strongly influence water supply and demand in the Willamette River Basin. Winters are cool and wet with abundant precipitation that swells the rivers, recharges soil moisture and groundwater, and creates snowpack in the basin’s Cascade mountain headwaters. In contrast, summers are warm and dry, with little precipitation to meet the warm-weather water demands of forests, agriculture, and cities. A system of 13 federal reservoirs managed by the U.S. Army Corp of Engineers (USACE), called the Willamette Project, also exert a strong influence on hydrology by reducing winter flood peaks and augmenting summer flows in the Willamette River mainstem and major tributaries draining the Cascade mountains. The reservoirs were built primarily to reduce flooding in the Willamette Valley, however they also serve other purposes such as power generation, recreation, and water supply for irrigation. Interest in the reservoirs as a water supply source has grown in recent years, and in 2016 the USACE and Oregon Water Resources Department re-initiated a study to consider how stored water is allocated for summer water needs.

Monthly mean precipitation in the Willamette Basin.

Figure 2. Mean monthly precipitation in the Willamette Basin.

Project Team


Photo of participants in the December 4, 2015, WW2100 Learning and Action Network Workshop. Photo credit:  Kayla Martin, OSU

Project researchers and Learning and Action Network team members gathered in Salem in December 2015 for a capstone workshop. Photo credit: Kayla Martin, OSU


Lead Principal Investigators

  • Jeffrey McDonnell, Oregon State University (OSU) College of Forestry, now at University of Saskatchewan, Global Institute for Water Security (2010-2012) 
  • Roy Haggerty, OSU College of Earth, Ocean, and Atmospheric Sciences (2012-2015) 
  • Anne Nolin, OSU College of Earth, Ocean, and Atmospheric Sciences (2015-2016) 

Executive Committee (alphabetical)

  • John Bolte, OSU Biological & Ecological Engineering
  • Barbara Bond, OSU Forest Ecosystems & Society (2010-2012)
  • Samuel Chan, Oregon Sea Grant
  • Roy Haggerty, OSU College of Earth, Ocean, and Atmospheric Sciences (2015-2016)
  • David Hulse, University of Oregon, Landscape Architecture
  • William Jaeger, OSU Applied Economics (2013-2016)
  • Philip Mote, Oregon Climate Change Research Institute
  • Anne Nolin, OSU College of Earth, Ocean, and Atmospheric Sciences (2012-2015)
  • Andrew Plantinga, UC Santa Barbara - Bren School of Environmental Science & Management (2010-2013)
  • Project Coordinator: Maria Wright, OSU Institute for Water and Watersheds

Other Research Team Members (alphabetical) 

  • Adell Amos, UO School of Law
  • Meagan Atkinson, MS Student, OSU Environmental Science (Graduated: 2014)
  • Chris Berger, PSU Civil & Environmental Engineering
  • Joe Bernert, Institute for Natural Resources
  • Dan Bigelow, PhD Student, OSU Applied Economics
  • Heejun Chang, PSU Geography
  • David Conklin, Oregon Freshwater Simulations
  • Matt Cox, OSU Biological & Ecological Engineering
  • Kathie Dello, Oregon Climate Change Research Institute
  • Laura Ferguson, MS Student, OSU Marine Resource Management (Graduated: 2015)
  • Elizabeth Garcia, PhD Student, UCSB (Graduated: 2014)
  • Kelly Gleason, PhD Student, Water Resources Science (Graduated: 2015)
  • Stephanie Graham, MS Student (Graduated: 2012)
  • Gordon Grant, USDA Forest Service
  • Stan Gregory, OSU Fisheries and Wildlife
  • Alexey Kalinin, MS Student, OSU Applied Economics (Graduated: 2013)
  • Andrea Laliberte, Earthmetrics
  • Stephen Lancaster, OSU College of Earth, Ocean, and Atmospheric Sciences
  • Christian Langpap, OSU Applied Economics
  • Sarah Lewis, OSU College of Earth, Ocean, and Atmospheric Sciences
  • Maria Lewis Hunter, MS Student, OSU Water Resources Policy and Management (Graduated: 2013)
  • Kayla Martin, Oregon Sea Grant
  • Myrica McCune, Institute for Natural Resources
  • Linda Modrell, Former Benton County Commissioner
  • Kathleen Moore, PhD Student, OSU Geography (Graduated: 2015)
  • Hamid Moradkhani, PSU Civil & Environmental Engineering
  • Anita Morzillo, OSU Forest Ecosystems & Society
  • Phil Neumann, MS Student, OSU Water Resources Science (Graduated: 2012)
  • Anne Nolin, OSU College of Earth, Ocean, and Atmospheric Sciences
  • Beau Olen, MS Student, OSU Applied Economics (Graduated: 2012)
  • Charles Preppernau, OSU Geography (Graduated: 2015)
  • Travis Roth, PhD Student, Water Resources Science 
  • David Rupp, Oregon Climate Change Research Institute
  • Mary Santelmann, OSU Water Resources Graduate Program
  • Cynthia Schwartz, OSU Biological & Ecological Engineering
  • Eric Sproles, PhD Student, Water Resources Science (Graduated: 2012)
  • Adam Stebbins, Benton County
  • Dan Stephens, OSU Geography (Graduated: 2016)
  • James Sulzman, OSU Biological & Ecological Engineering
  • Christina (Naomi) Tague, UC-Santa Barbara
  • Desiree Tullos, OSU Biological & Ecological Engineering
  • David Turner, OSU Forest Ecosystems and Society
  • Kellie Vache, OSU Biological & Ecological Engineering
  • Eric Watson, PSU Geography (Graduated: 2016)
  • Scott Wells, Portland State University (PSU) Civil & Environmental Engineering
  • Josh Williams, MS Student, OSU Fisheries and Wildlife (Graduated: 2014)
  • Junjie Wu, OSU Applied Economics


Technical Advisory Group (TAG) (alphabetical)

Beginning in project year 5 (fall 2014), we invited a core group of 25 citizen stakeholders to participate in a series of meetings to define the assumptions for two stakeholder scenarios and provide feedback on communicating project findings.  TAG members included: 

  • Rick Bastasch, Straub Environmental Center
  • Jason Bradford, Vitality Farms
  • Kevin Brannan, Oregon Department of Environmental Quality
  • Stephanie Eisner, City of Salem
  • Bob Heinith, Columbia River Inter-Tribal Fish Commission
  • Johan Hogervorst, USDA Forest Service
  • Gary Horning, Horning Farm
  • Allison Inouye, City of Hillsboro
  • Niki Iverson, City of Hillsboro
  • John Harland, Pacific Northwest Pollution Prevention Resource Center
  • Margaret Matter, Oregon Department of Agriculture
  • Matt McRae, City of Eugene
  • Jim Meierotto, Tualatin Valley Water District
  • Linda Modrell, Benton County
  • Karl Morgenstern, Eugene Water and Electric Board
  • Alyssa Mucken, Oregon Water Resources Department
  • Laurie Nicholas, US Army Corps of Engineers
  • Dan Obrien, Greenberry Irrigation District
  • Michelle Plambeck, Multnomah County
  • Kimberley Swan, Clackamas Water Providers
  • Gregory Taylor, US Army Corps of Engineers
  • Tom VanderPlaat, Clean Water Services


Learning and Action Network (LAN)

Throughout the project, the science team met with regional water managers, stakeholders, and educators.  This group was called the Learning and Action Network (LAN) and grew to include county commissioners, managers, and scientists from state and federal natural resource agencies, farmers, K-12 educators, and representatives from water utilities, conservation organizations, and industry.  Over 120 people participated in at least one LAN event over the project's six years.  LAN events consisted of fieldtrips, workshops, and webinars, where we encouraged dialogue about water issues in the basin and introduced and received feedback on WW2100 modeling approaches and analysis. 

Project Outcomes

The goal of the Willamette Water 2100 project was to develop tools and understanding that will help anticipate water scarcity and inform integrated water system management. Here we highlight some of the key outcomes from the project:

Outcome 1: Development of Willamette Envision

The Willamette Water 2100 project team developed Willamette Envision, a computer model of human and natural controls on water supply and demand across the Willamette River Basin.

Some of the unique aspects of the model include:

  • Landscape modeling at a fine spatial and temporal resolution,
  • A process-based hydrologic model that incorporates human influences such as dam operations, water diversions, and the water rights system, and
  • The ability to run alternative scenarios to explore uncertainty and the affect of changes in land and water management policies.

Outcome 2: Development of a quantitative water budget for the Willamette Basin

The water budget illustrates some of the key characteristics of Willamette water system and how it might respond to coming pressures from climate change and populations growth.

Related findings:

  • In a system where water supply and demand are strongly seasonal and asynchronous, natural and built reservoirs play an important role in sustaining summer flows.
  • Warmer conditions caused by climate change will reduce winter snowpack, stress forests, and could increase the land area burned by wildfires. In model simulations the net effect of these changes and increases in winter precipitation was an increase in annual streamflow.
  • Climate warming could lead to earlier planting dates and an earlier start and end to the irrigation season for annual crops. This shift could reduce out of stream water demands in late summer in some sub-basins.
  • Population growth will increase water demand for cities, while water demand for agriculture may remain relatively constant. Growing cities will displace irrigated farmland, while legal and economic constraints limit the development of new irrigation projects. The trajectory of urban water demand will depend on factors such as population and income growth, development density, water price, and the availability of major water sources outside the Willamette Basin.

Outcome 3: Development of a framework for understanding water scarcity

The framework provides context for understanding water scarcity in the Willamette River Basin and beyond.

Related findings:

  • Water scarcity can be described along a continuum, determined by the value of providing additional water at specific times and places. For example, high water scarcity occurs when and where the value of providing additional water is high. For a more complete discussion of the concept of water scarcity, refer to Jaeger et. al. (2013).
  • Water scarcity has spatial, temporal and qualitative dimensions. Water scarcity in the Willamette River Basin illustrates all of these dimensions:
    • Water is annually abundant but seasonally scarce in summer when demand peaks but little rain falls. 
    • Water may be available regionally, but can be scarce at specific locations in the basin because of legal constraints or the lack of infrastructure. 
    • Water may be abundant, but not of use if it does not meet desired or required water quality standards. In the Willamette, many native fish species require cold water habitats, habitats that may be degraded by climate warming and land development. 
  • Water scarcity can be driven by human decisions, costs, laws and regulations, as much as by a lack of physical abundance. In the Willamette system, summer water storage by the federal dams in the Willamette River Basin provides the biggest single mechanism to mitigate potential water scarcity for humans and ecosystems. However, access to this water is limited by an array of water laws, regulations, and competing needs. Two examples include:
    • Trade-offs between flood risk reduction and water storage for summer use. Reducing spring flood risks requires maintaining reservoirs empty longer, yet that also reduces the time available to fill reservoirs for summer use.
    • Restrictions imposed by federal environmental laws. Rules to mitigate the impact of federal dams on threatened and endangered fish strongly influence dam operations and summer flow releases. In quantitative terms, minimum regulatory instream flow requirements established by ESA-related Biological Opinions are a major summer water use, one that exceeds basinwide agricultural and urban water demands, and will likely limit future access to stored water.

Outcome 4: Capacity building

Adopting a transdisciplinary approach that involved regional water managers and stakeholders in all stages of the research process helped build capacity for integrated water system management.

Related findings:

  • Extensive stakeholder engagement throughout the project helped foster relationships and learning between scientists and stakeholders, and between stakeholders in different sectors.
  • As a university led project with a wide scope, the project provided a neutral forum for learning among water sectors. Interviewed stakeholders valued the opportunity to build relationships with diverse water users, regulators, and researchers, and to discuss possible water availability constraints of the future.

Funding & Disclaimer

WW2100 was funded predominantly by research grants from the National Science Foundation (NSF) with additional support from the US National Oceanic and Atmospheric Administration (NOAA).  Grants included:


  • NSF-EAR 1039192 to Oregon State University
  • NSF-EAR 103889 to University of Oregon
  • NSF-EAR 1038925 to Portland State University, and
  • NOAA NA10OAR4310218 to Oregon State University and the University of Oregon

The project was affiliated with the NSF Water Sustainability and Climate (WSC) program, an effort to enhance understanding of the Earth's water system and interactions between human activity, climate change, and ecosystem functions.  NSF's WSC program supported place-based modeling projects at universities across the United States. The OSU Institute for Water and Watersheds provided administrative support for the project, and the Institute for Natural Resources assisted with data management.

Any opinions, findings, conclusions or recommendations expressed on this website are those of the authors and do not necessarily reflect the views of the National Science Foundation or the National Oceanic and Atmospheric Administration. 

Contact Information

Principal Investigator:

Dr. Anne Nolin, Professor
College of Earth, Ocean, and Atmospheric Sciences
Oregon State University
Phone: 541-737-8051
Email: [email protected]


Project Coordinator:

Maria Wright, Faculty Research Assistant
Institute for Water and Watersheds
Oregon State University
Phone: 541-737-6148
Email: [email protected]

About this Website

This website is a companion to the project’s scientific publications, and provides an overview of project methods and findings, and a portal to access publications, data products, and unpublished project materials. It also contains sections describing the project’s broader impacts activities such as engagement with regional stakeholders, and training provided to university students and K-12 students and teachers. Most of the material on this site was developed in 2015 and 2016 by the WW2100 research team and was edited by Maria Wright, Anne Nolin, and Abby Metzger. The technical sections (under "Analysis by Topic") were written by subject matter experts - refer to the "more information" tab of each section for author name(s) and posting date.