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 when 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.