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Integrating Climate Adaptation into Water System Planning: CIG’s Collaboration with WA Dept. of Health

Drinking water systems have long planned for an uncertain future— a difficult task made more challenging due to a changing climate.

Climate-change driven impacts in Washington’s water supply and quality directly challenge the infrastructure and capacity of water systems. While water systems face uncertainty around future conditions, there are strategies water systems can undertake now to build climate resilience. This past year, the Climate Impacts Group worked with the Washington State Department of Health (DOH) to develop a water system planning climate resilience element to help Washington’s water systems prepare for climate change and increase climate resiliency.

Climate Change Impacts on Water Systems

Climate change will continue to alter the environmental and hydrologic conditions Washington’s water systems rely upon. Year round warming will lead to more winter rain instead of snow, less snowpack, and increased warm-season evaporation. Compounded with less summer rain, these changes are expected to continue exacerbating drought, and increasing demand when water is least available. Crucially, dwindling snowpack provides less recharge to rivers and aquifers that many water systems rely on.

The increasing frequency of extreme weather also creates acute challenges to drinking water infrastructure and quality: for example, flood waters from extreme rainfall and rapid snowmelt events can damage drinking water reservoirs, pipes, and treatment plants, thus interrupting services. Wildfires can increase turbidity and release hazardous compounds into drinking water sources, increasing water treatment costs. Flooding, and rising sea levels also elevate the risk of contamination in drinking water. With proactive, long-term planning that incorporates impacts of a changing climate, water systems can better anticipate these challenges, prepare for the impacts, and adapt infrastructure to ensure that communities have reliable & safe water.

“Whether a system is just beginning to consider climate impacts  or has decades of experience, the WSP Climate Resilience Element aims to meet water systems where they are and support forward-looking, locally grounded planning.”

 

Anne Thebo, Research Scientist

Water System Planning in Washington

Water System Plans (WSP) are a longstanding planning framework that support water systems in identifying and responding to current and future challenges. In Washington state, the Department of Health (DOH) and the Department of Ecology (Ecology) require WSPs to describe current demand, project future needs, and outline actions and water resource needed to maintain system reliability, sustainable water supply, and protect public health. By identifying both present vulnerabilities and emerging risks in collaboration with the water resource authority, Ecology, WSPs are well-positioned to support water systems’ development of a locally-tailored roadmap for addressing the long-term impacts of climate change.

Historically, however, consideration of climate impacts in water system planning has varied widely across Washington. To address these disparities, the state legislature passed House Bill 1181 in 2023. The Bill updates the state’s planning framework by requiring WSPs to include a ‘Climate Resilience Element (CRE),’ ensuring systems evaluate and plan for emerging climate-related risks. The aim of this requirement is to help build water systems capacity to respond to climate impacts and reduce disparities in climate preparedness across systems.

Climate Impacts Group Involvement

HB1181 tasked the Climate Impacts Group with supporting DOH’s development of the WSP CRE, recently published in the updated Water System Planning Guidebook. Resources developed as part of this effort include the supplemental DOH WSP Climate Resilience Element workbook and a webpage with curated resources. “This new requirement provides an important opportunity to connect water system practitioners with a broad array of established tools and resources designed to strengthen system resilience to emerging climate-related risks,” describes Ryan Hasert, CIG Scientist and co-author of the CRE.

State and local decision-makers can use CIG’s tools to find relevant information to plan for climate resilience in their water system plans, like Climate Mapping for a Resilient Washington, Average projected changes in temperature and precipitation in the PNW, and Future projections of sea level change across coastal Washington.

“This new requirement provides an important opportunity to connect water system practitioners with a broad array of established tools and resources designed to strengthen system resilience to emerging climate-related risks.”

 

Ryan Hasert, Research Scientist 

The Water System Plan Climate Resilience Element

To comply with the new WSP CRE requirement (RCW 43.20.310), systems are required to identify climate related challenges & actions needed to address these challenges, and incorporate these actions into their infrastructure and financial plans. Essentially, “the Climate Resilience Element provides a guiding framework designed to help water systems identify locally-significant climate risks and prioritize strategies to manage them,“ explains CIG Scientist and co-author of the CRE, Anne Thebo.

The table below provides an idea of what each requirement can look like in practice:

Resilience Requirement

Requirement Criteria

Example
Understand Exposure & Assess Vulnerability Identify climate-related challenges and impacts 2015: The City of Vancouver was concerned about changes in water demand associated with climate change and, in response, conducted an analysis evaluating historical relationships between temperature, precipitation, and demand. Lack of local data, uncertainty around the timing of future events, and weak correlations in the historical data limited their inclusion of future climate projections at that time, though the WSP notes potential impacts and makes recommendations for future work.
Investigate Options Identify actions needed to respond to climate-related impacts 2019:  After analyzing climate-related challenges to their water system, the City of Port Townsend’s WSP identified a series of priority actions. These actions included implementing conservation measures, improving water use efficiency, creating drought-resistant landscaping, and expanding water storage capacity.
Prioritize and Plan Incorporate climate resilience actions into WSP capital improvement and financial programs. 2021: A 1992 report identified saltwater intrusion from sea level rise as a risk to Olympia’s water supply wells. In the intervening years, planning for a secondary well field and investments in demand management were prioritized. Olympia’s 2021 WSP details major investments in climate resilience strategies such as the construction of the upland wellfield, but also interties with neighboring systems, water reuse projects, and extensive community engagement efforts.

Footnote: Above examples demonstrate how the resilience requirements have been previously implemented in water systems before HB1181, not in response to HB 1181.

Looking forward

Water systems in Washington state are facing an increasingly diverse set of climate-related stressors and uncertainties, often compounding existing technical, managerial, and financial challenges. The requirements defined in the WSP CRE build on each other, culminating in a locally grounded plan for building water system resilience to anticipated climate challenges. “Whether a system is just beginning to consider climate impacts or has decades of experience, the WSP Climate Resilience Element aims to meet water systems where they are and support forward-looking, locally grounded planning,” Thebo summarizes. A flexible, inclusive approach offers a practical path for all water systems –regardless of their starting point–to make meaningful progress toward climate resilience.

For more information, contact Anne Thebo (UW) at thebo@uw.edu or John Freitag (DOH) at John.Freitag@doh.wa.gov.