The Challenges for Incorporating Climate Change and Variability Information Into Water Supply Decision Making.

1. The Challenges for Incorporating Climate Change and Variability Information Into Water Supply Decision Making. Presented by Lorna Stickel Portland Water Bureau & Regional Water Providers Consortium Project Manager WGA/WSWC/CDWR Workshop on Climate Change Research Needs May 16-18,2007

2. Topics for This Presentation • Potential impacts of climate change on municipal water systems • Planning for impacts with examples from Portland & Pacific NW area • Climate change strategies • More research and data needed

3. Past Climate Variability • Paleoclimatology research involving ice cores, tree rings,shells,ocean/lake sediments, etc. have been used to simulate past climates. The research indicates significant variation in the past beyond our traditional climate records. • In the Columbia Basin there have been longer extended periods of drought than our typical climate records show. 1840-1855 is the drought of record over the last 250 years. The period from 1950-1987 was notable for having no multiyear droughts in the bottom 15th percentile.

4. How might Municipal Water Supplies be affected by Climate Change? • The hydrology of sources may be more affected than the demands for future growth, likelihood of longer drought periods as well as lower summer stream flows, and potentially larger flood events in the winter. • Competition for water resources is increased, thereby affecting water right status/conflict. • Lower summer instream flows affects ESA species/HCP requirements and water quality/ CWA permit requirements as well as treatment assumptions/operations.

5. Added uncertainty in planning for Municipal Water Supplies • Most planning for water supplies is based on short climate records, not reflective of longer climate variability or future projections thereby creating water supply systems that are not as reliable . • The synergy between lower summer streamflows, less summer rainfall, higher temperatures and increased competition creates an effect that is going to stress municipal systems more than in the past. • Extreme events are likely to be off the chart - affecting system reliability due to sea level rises, saltwater intrusion, more intense storm events, fires, water quality changes, and more.

6. Potential Impacts on Municipal Water Demands • Temperature and precipitation are major factors that affect daily demand patterns. Climate change scenarios with higher temperatures are likely to mean higher overall demand. In some areas this will mean higher peak season demand and in others higher year round demands. In most areas increases in late summer/fall demands may be the most problematic. • Climate change likely to mean higher demand patterns than seen in the past, or greater frequency of “worst” weather years. • Climate change resonates with customers. Can result in greater acceptance of conservation programs and needed behavioral changes in consumption.

7. Can I determine how climate change might impact my water system? • The impacts are different for each system studied, in some cases no impacts may be found due to large system interactions (e.g. a study done for the Eugene Electric and Water Board in Oregon) while in others the impacts will be significant, particularly over longer periods of time (50 years or more). • The impacts of global climate change can be difficult to project at the local or regional level, modeled future temperature trends are more consistent than precipitation. • Yes, it is possible to assess the range of climate change impacts at the local/regional level.

8. Global Climate Models translated to local impacts Five step process outlined by Glieck & Frederick (1999) • Look at several Global Climate Models (GCMs) and look for consensus & ranges • Downscale to level needed using quantile mapping • Apply impact ranges to hydrologic modeling • Develop systems simulation models • Assessment of the results (historic and GCMs at representative time frames. Pacific NW example

9. Climate Change and Water Supply Planning in the Pacific NW • Most Water providers have not considered climate change directly in their Water Master Plans, however, some sources have had climate change studies conducted to look at potential impacts: • Bull Run, Portland, Oregon - 2002 • Tualatin Basin, Oregon – 2004 • Seattle, Washington – 2004 & Present • See U. of Washington Climate Impacts Group (CIG) website for copies of the above reports: www.cses.washington.edu/cig/fpt/caseplanning.shtml • Eugene and the upper Clackamas have had studies done relating to geo-hydrology and climate change.

10. Impacts to Municipal Sources of Supply in Pacific NW • Run of River – Changes in snow and rainfall patterns affect the periodicity of streamflows, more intense winter flows and lower summer flows appear to be common outcomes • Storage – Reliability of storage projects changes • Demands are higher in the peak season • Less inflow affects both filling of some projects annually and reduces the amount of surface water inflow during the summer. Reliability of supplies becomes less in the summer. • GW – Not sure of the impact on these systems, but if GW is pumped more to meet increased needs then declines in water levels could result and/or impacts on surface water sources could be greater, some aquifers may gain more recharge if precipitation increases in winter. • The past 60-80 years of record shows great variability for surface water sources, climate change will result in seeing even more variability.

11. Results of the Portland Climate Change Study 2002 • The Bull Run is in a transient watershed where climate change scenarios show more water coming as rain in winter and less snow pack to boost inflows in the Spring. • The Bull Run reservoirs will still fill in every year, however, the number of years with longer drawdown periods increases. • Shows that water supplies will be stressed more by future growth, but that climate change will compound that impact.

12. Bull Run Study: Impacts to Snowfall

13. Bull Run Study : Impacts on Demand • 8% peak season increase by 2040 • 4% annual average increase by 2040 • Water demands shown to be less sensitive to climate change than the hydrology

14. Modeled Demand on the Portland System in 2040

15. Climate Change Strategies Planning • Larger supplies as well as supplies on rivers that have multiple intakes and inflows should consider modeling climate change impacts, particularly where overall precipitation is expected to decrease and/or where snowpack is a significant portion of storage and/or live summer flows. • Assess the effects on multiple sources at the same time if possible, otherwise you have disparate decision making information. • Include climate change effects on both hydrology and water demand patterns. • Assess the role of curtailment and the effects of hardening demand through conservation measures.

16. Climate Change StrategiesPlanning • Work at the watershed level appropriate for larger scale impact assessment. • Use integrated models to simulate climate impacts on supply operations including fish flows and water quality issues (e.g. CWA/TMDL’s). • Look at the newer climate change models being developed for the 2007 Intergovernmental Panel on Climate Change Conference, for the Pacific NW these indicate a somewhat slower pace of temperature increases than earlier models, but could be different for other areas. • Identify “No Regrets” strategies which deal with both climate change and other current issues (e.g. growth, fish, vulnerabilities, new regulations, wastewater, maintenance) so that there are multiple benefits regardless of climate change.

17. Climate Change StrategiesInfrastructure Development & Use • Consider more conjunctive use of sources including surface, groundwater, and ASR. • Build more system reliability through interconnections and backup supplies for emergencies and more frequent shortages of primary supplies. • Assess climate impacts on fire regimes in municipal watersheds (including vegetative changes due to climate change) • More close monitoring & modeling of short term system operations and put in place strategies for dealing with summer supplies in real time.

19. Climate Change StrategiesInfrastructure Development & Use • More storage (dams and ASR) may be necessary to capture the higher winter flow events. • Assess the potential impacts of changing flood rule curves on municipal and multiple purpose storage projects. • In some areas climate change could positively change the cost/benefits of reuse and non-potable supplies. • Evaluate the extreme events possibilities that apply to your situation, particularly multi-year droughts, flooding and sea level rises, and assess various system vulnerabilities.

20. Mitigation by Utilities Are there mitigation strategies that utilities can adopt to limit the impacts of climate change? • Assess sustainability actions and adopt practices that incorporate reducing greenhouse gas emissions. • Use full cost or triple bottom line accounting for decision making (economic, social, environmental). • Reduce fossil fuel use, switch to other sources for fleet or electrical energy, change out vehicles • Reduce energy use overall (lighting, paper, etc.) • Provide more dual programs for conservation that reduce energy and water use. • Purchase carbon offsets if available

21. Climate Change StrategiesProgrammatic and Institutional Actions • Work with statewide and multi-state entities to engage multiple stakeholders: • Look to NOAA Regional Integrated Sciences and Assessment agencies (RISAs) in Pacific NW, Central Rockies,Cal/Nev, Arizona/NM, SE and NE US for scientific and technical assistance. • Western Regional Climate Center in Reno, NV. Covers all of the Western states. • Sponsor or participate in local, state, and regional climate conferences such as the one recently held in Seattle, Washington (see CIG website). • Build more relationships with non-profit agencies working on climate change issues such as NCAR/AWWARF studies.

22. Climate Change StrategiesProgrammatic and Institutional Actions • Use Conservation Programs and pricing to moderate demand effects, particularly during the peak season. These programs can be justified to offset climate change effects on both demand patterns and instream resources. • Develop curtailment plans in a regional context. • Encouraging more active use of transfers, water markets, water banking, limited duration permits, and “interruptable” water rights to provide added flexibility to deal with change. • Public needs to be included in the decisions about system reliability in times of uncertainty about future supplies. • Forge relationships between local decision makers and academic institutions to understand what the data tells us and how climate change may impact the provision of municipal water supplies, advocate for applied research opportunities.

23. More Research Needed There is a lot that isn’t known about climate change impacts on municipal supplies: • Only limited studies have been done, and even then broad assumptions have to be made about the local effects. More paleoclimate studies should be done to understand past variabilities, this will make future predictions more cogent. • The impacts on hydrology are the most important unknowns that need to be researched, particularly for urban water sources. Impacts of storm tracks and geographic features need to be better understood. • Impacts on groundwater needs to be researched, as well as the relationship of groundwater recharge to surface water flows. • Summer climate change impacts on rainfall patterns are not as well predicted as temperature increases.

24. More Research Needed • Reliable longer term data on production, stream flows, and consumption needs to be collected and available for analysis. • The ability to model complex systems (eg. WEAP model, Stella based models, and others) is increasing, but the application to local systems will take resources and time. Synergistic climate effects between flows, fish, flooding, hydro, and water demand patterns present a complex picture that needs more study. • The role of conservation, reuse, and curtailment need to be better integrated into long supply planning in more parts of North America.

25. Getting Past the Controversy The science of climate change while important, isn’t the where the action is, it’s about the perceptions of the issue and the communications driving changes. An important aspect of research is to agree on the critical potential outcomes. This will help decision-makers to both adapt to climate change and to mitigate where possible.

26. What does all this mean? • We have a fairly narrow record on which we have based our estimates of the variation of climate, even the past 250 years indicates that we have had more significant multi-year droughts. We don’t need to overreact, but we need to either start now or continue to incorporate the flexibility we will need. • Climate change could be pushing us faster towards more prolonged drier multi-year events like the past. • We may not know the specifics, but we still need to consider the trends in our planning for future supplies and contingencies. The public focus will dictate this and it’s better than being poked in the eye with a sharp stick.

27. Final Thought “Climate is an angry beast and we are poking at it with sharp sticks.” Wallace Broecker, Columbia University Doherty Earth Observatory.

28. Contact Information Lorna Stickel Portland Water Bureau 1120 SW 5th Ave., Room 600 Portland, Oregon 97204 Phone: (503) 823-7502 E-mail: lstickel@water.ci.portland.or.us

30. Climate Change study done for the Portland Water Supply • Contracted with the University of Washington - Dr. Richard Palmer and Margaret Hahn (now Margaret Ales of RW Beck) in 2002. • Study based on downscaling 4 global climate change models to create 4 sets of changes in temperature and precipitation, applied to a Distributed Hydrology, Soil-Vegetation Model of the watershed, and placed into a Stella based integration model called the Storage and Transmission Model (STM) developed for Portland. • The STM also used data developed by the Portland Water Bureau on daily water demands and fish flows to protect ESA fish species in the Bull Run watershed. • Different climate change scenarios were developed based on the different climate model results using the patterns of specific past climate years applied to future water demands out to 2040.