Including climate change information in water resource planning and management can reveal new vulnerabilities of a system to climate change and uncover ways to improve system resilience. This aligns with the traditional planning process, which tests system responses to a range of hydroclimate conditions (from normal to extreme) along with a broad range of other factors that determine system performance, including changes in demographics, system demands, environmental constraints, infrastructure concerns, and finance scenarios. Evaluations of a system’s vulnerability to climate change must be undertaken via the addition of a broader range of possible futures than are indicated by historical records alone, although they need not be a separate project (e.g., mainstreaming climate change considerations, Vogel et al. (2016b)).

A major benefit of considering how a water system will be impacted by future change is that it raises questions of how the current system is understood and how it might be understood better (Vanrolleghem 2010). This can lead to innovations that can help improve a water system’s hydrologic modeling capabilities generally. For example, the Portland Water Bureau used a climate assessment as an opportunity to set up an in-house hydrologic model for the Bull Run watershed, Portland’s primary water supply (Vogel et al. 2016a). Additionally, understanding ways to be more prepared for climate-driven impacts and addressing the inherent uncertainties in future climate in planning can improve a water system’s adaptive capacity for non-climate-driven impacts as well (Olsen et al. 2015; Frietag et al. 2012) and motivate and facilitate improvements in ongoing management, including drought monitoring, streamflow forecasting for floods and droughts, and enhanced water conservation.

Climate change evaluations also build human capacity. They often require decision makers address difficult questions such as how to value dissimilar types of impacts (Willows and Connell 2003). They can motivate people with different management goals such as irrigation districts and environmental groups to work together (Eberhart et al. 2013; Malloch and Garrity 2015). Ultimately, the ability of a community to rapidly recover from a disaster is increased when a diverse group of stakeholders can work together to monitor potential hazards and modify plans and activities to accommodate future change (NRC 2011).

The American Society of Civil Engineers’ Committee on Adapting to Climate Change recommends a modified version of the Observational Method as a useful approach for including climate change in planning that would also make the system more adaptable to other changes (e.g., population and land use change). The goal of the Observational Method, developed in geotechnical engineering over 60 years ago, is to design a system with contingencies for all foreseeable problems the system might face. Then, the system is continuously monitored (in a reliable, transparent way) for metrics which indicate when it is time to enact the contingencies. This assures safety and allows for more economic design, as long as changing conditions are monitored and design modifications are possible including funds, authority, and willingness. An example would be increasing water storage incrementally through time to store water to compensate for disappearing snow pack. If future flexibility is not guaranteed or there is no solution for all hypothetical problems, even those with low probability of occurrence, then the design should be based on least favorable conditions (Olsen et al. 2015). The method is helpful for gradual changes that can be monitored. For water resources, this could help in adapting to sea-level rise or changing permafrost, but may not be appropriate for extreme events where damages may occur before changing conditions can be observed (Olsen et al. 2015).

Consideration of climate impacts can provide motivation to overcome longstanding differences. As a newspaper article jointly written by an irrigator, an environmentalist, and a tribal member states, “After 30 years of conflict and increasingly frequent drought in the Yakima River Basin, a diverse coalition of farmers, conservationists, the Yakama Nation, and government officials have hammered out a national precedent-setting vision to improve water security for farms and communities, bring back salmon and steelhead, and protect and restore the streams and forests of the river’s headwaters” (Eberhart et al. 2013). This unusual coalition was largely motivated by climate concerns, coupled with endangered fisheries and a failed attempt to build the Black Rock Reservoir (Malloch and Garrity 2015). The climate impact studies, done at the University of Washington from 2007 to 2009, showed the basin was especially susceptible to loss of snowpack, a water supply source that allows the basin’s five constructed reservoirs to hold water for irrigation from the region’s wet winter to the dry summer (Elsner et al. 2010; Vano et al. 2010b).