Climate Change and Climate Change and Municipal Water SuppliesMunicipal Water Supplies

Presented by Lorna StickelPresented by Lorna Stickel

Portland Water Bureau and Portland Water Bureau and Regional Water Providers Regional Water Providers Consortium Project ManagerConsortium Project Manager

How are Municipal Water How are Municipal Water Supplies affected by Climate Supplies affected by Climate Change?Change?

1.1. Water demands are increased by Water demands are increased by increases in temperature in the summer increases in temperature in the summer months, beyond the effects of growth.months, beyond the effects of growth.

2.2. The hydrology of sources is affected even The hydrology of sources is affected even more than the demands.more than the demands.

3.3. The competition for water resources is The competition for water resources is increased, thereby affecting water rights.increased, thereby affecting water rights.

4.4. Summer instream flows are less affecting Summer instream flows are less affecting ESA species/HCP requirements and CWA ESA species/HCP requirements and CWA permit requirements.permit requirements.

Topics for This Topics for This PresentationPresentation

1.1. Past Regional Planning and Past Regional Planning and Climate ChangeClimate Change

2.2. Potential impacts of climate Potential impacts of climate change on municipal supplies, change on municipal supplies, some examples from the Portland some examples from the Portland metro area.metro area.

3.3. How municipalities might deal How municipalities might deal with climate change including with climate change including more research that is needed.more research that is needed.

Water Supply Planning in Water Supply Planning in Portland RegionPortland Region

Most Water providers have not considered climate Most Water providers have not considered climate change directly in their Master Plans, however, change directly in their Master Plans, however, two sources have had climate change studies two sources have had climate change studies conducted:conducted: Bull Run - 2000Bull Run - 2000 Tualatin Basin - 2004Tualatin Basin - 2004

Regional planning between 1993-2004 did not Regional planning between 1993-2004 did not consider the direct effects of climate change, but consider the direct effects of climate change, but did recognize the potential for impacts.did recognize the potential for impacts.

The RWSP Update of December 2004 does contain The RWSP Update of December 2004 does contain two pages on climate change and the two studies.two pages on climate change and the two studies.

Regional Water Supply Regional Water Supply Plan Plan

Planning for supplies in the Portland area Planning for supplies in the Portland area included aspects of meeting drought needs included aspects of meeting drought needs within the Regional Water Supply Plan (RWSP) within the Regional Water Supply Plan (RWSP) & Update through:& Update through:• Water Demand Forecasting – Uses the actual climate Water Demand Forecasting – Uses the actual climate

patterns of the years 1940-2003 within an patterns of the years 1940-2003 within an econometric model that predicts daily water econometric model that predicts daily water demands.demands.

• Integrated modeling in Confluence allowed looking at Integrated modeling in Confluence allowed looking at weather events of the past so that those (eg. 1968 weather events of the past so that those (eg. 1968 for peak season and 1981 for peak day) that drove for peak season and 1981 for peak day) that drove demands higher were selected for analysis.demands higher were selected for analysis.

Regional Water Supply Regional Water Supply Plan Plan

Conservation Programs selected that Conservation Programs selected that focus on summer peak season uses.focus on summer peak season uses.

Interties have been constructed and Interties have been constructed and more are proposed to connect sources more are proposed to connect sources better and to encourage conjunctive better and to encourage conjunctive and efficient use of existing supplies.and efficient use of existing supplies.

Non-potable and reuse are also Non-potable and reuse are also encouraged where feasible and cost encouraged where feasible and cost effective.effective.

Climate Change and Impacts Climate Change and Impacts to Municipal Sources of to Municipal Sources of SupplySupply

Impacts to Sources of SupplyImpacts to Sources of Supply• Run of River – Changes in the periodicity of streamflows, Run of River – Changes in the periodicity of streamflows,

more intense winter flows and lower summer flowsmore intense winter flows and lower summer flows• Storage – Reliability of storage projects changes Storage – Reliability of storage projects changes

– Demands are higher in the peak seasonDemands are higher in the peak season– Less inflow affects both filling of some projects annually and Less inflow affects both filling of some projects annually and

reduces the amount of surface water inflow during the reduces the amount of surface water inflow during the summer.summer.

• GW – Not sure of the impact on these systems, but if GW GW – Not sure of the impact on these systems, but if GW is pumped more to meet increased needs then declines in is pumped more to meet increased needs then declines in water levels could result and/or impacts on surface water water levels could result and/or impacts on surface water sources could be greater.sources could be greater.

• The past 60 years of record shows great variability for The past 60 years of record shows great variability for surface water sources, climate change will result in seeing surface water sources, climate change will result in seeing even more variability.even more variability.

Bull Run Summer Inflow 1940-2004 Millions of Gallons (June-Oct)

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

Mill

ion

s o

f G

allo

ns

Highest Yield1955 - 71.8 BG

Lowest Yield 1987 - 10.9 BG

Bull Run Study: Impacts to Bull Run Study: Impacts to SnowfallSnowfall

Climate Change and Impacts Climate Change and Impacts to Municipal Water Demandsto Municipal Water Demands

DemandsDemands• Temperature and rainfall are major factors Temperature and rainfall are major factors

that affect demand patterns during the peak that affect demand patterns during the peak season.season.

• Even higher demands in peak season at the Even higher demands in peak season at the same time that supplies might be less.same time that supplies might be less.

• Climate change likely to mean more severe Climate change likely to mean more severe demand patterns than seen in past, or greater demand patterns than seen in past, or greater frequency of “worst” weather years.frequency of “worst” weather years.

• Fish & water quality instream needs also will Fish & water quality instream needs also will compete more frequently with out of stream compete more frequently with out of stream demands.demands.

2005 Portland Regional Peak Season (Jun-Oct) Average Water Demand in MGD Over the Weather Years 1940-2000

220

230

240

250

260

270

28019

40

1942

1944

1946

1948

1950

1952

1954

1956

1958

1960

1962

1964

1966

1968

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

MG

D

Highest Value272.8 MGD

1968

Lowest Value 238.2 MGD1954 Peak Season

Maximum Variation 34.6 MGD

Bull Run Study : Impacts on Bull Run Study : Impacts on DemandDemand

• Water demands shown to be less affected Water demands shown to be less affected

by climate change than hydrologyby climate change than hydrology

• 8% increase in 2040 drawdown demand8% increase in 2040 drawdown demand

• 4% increase in 2040 average annual 4% increase in 2040 average annual

demanddemand

Climate Change and Impacts Climate Change and Impacts to Municipal Water Systemsto Municipal Water Systems

• Most planning for water supplies is based on Most planning for water supplies is based on past history, and often not a very long past history, and often not a very long history.history.

• The synergy between lower summer The synergy between lower summer streamflows, less summer rainfall and streamflows, less summer rainfall and higher temperatures creates an effect that higher temperatures creates an effect that is going to stress municipal systems more is going to stress municipal systems more than past.than past.

• If suppliers only evaluate the past history If suppliers only evaluate the past history then we may be creating water supply then we may be creating water supply systems that are not as reliable.systems that are not as reliable.

Dealing with Climate Dealing with Climate ChangeChange

PlanningPlanning• Larger supplies as well as rivers that have multiple Larger supplies as well as rivers that have multiple

intakes should model climate change impacts as has intakes should model climate change impacts as has been done for Portland’s Bull Run and for the Tualatin been done for Portland’s Bull Run and for the Tualatin Basin.Basin.

• Assess the effects on multiple sources at the same Assess the effects on multiple sources at the same time if possible, more study is needed in the Portland time if possible, more study is needed in the Portland area to include the Clackamas River particularly, but area to include the Clackamas River particularly, but also the Willamette and the impacts on storage.also the Willamette and the impacts on storage.

• Include climate change effects on both the hydrology Include climate change effects on both the hydrology and water demand patterns.and water demand patterns.

• Assess the role of curtailment, particularly in light of Assess the role of curtailment, particularly in light of more extreme events (drought and flooding) and more extreme events (drought and flooding) and hardening of demand through conservation.hardening of demand through conservation.

Dealing with Climate Dealing with Climate ChangeChange

Infrastructure Development & UseInfrastructure Development & Use• Consider more conjunctive use of sources Consider more conjunctive use of sources

including surface, groundwater, and ASR.including surface, groundwater, and ASR.• Build more system interconnections and Build more system interconnections and

backup supplies for emergencies or more backup supplies for emergencies or more frequent shortages of primary supplies.frequent shortages of primary supplies.

• More close monitoring & modeling of short More close monitoring & modeling of short term system operations and put in place term system operations and put in place strategies for dealing with summer supplies in strategies for dealing with summer supplies in real time.real time.

• More storage may be necessary to capture More storage may be necessary to capture the higher winter flow events.the higher winter flow events.

Dealing with Climate Dealing with Climate ChangeChange

Programmatic ActionsProgrammatic Actions Assess the potential impacts of changing flood rule Assess the potential impacts of changing flood rule

curves on multiple purpose projects.curves on multiple purpose projects. Use Conservation Programs to moderate demand effects, Use Conservation Programs to moderate demand effects,

particularly during the peak season. These programs can particularly during the peak season. These programs can be justified to offset climate change effects on both be justified to offset climate change effects on both demand patterns and instream resources. demand patterns and instream resources.

Develop curtailment plans in a regional context.Develop curtailment plans in a regional context. Encouraging more active use of water markets and water Encouraging more active use of water markets and water

banking to provide added flexibility to deal with change.banking to provide added flexibility to deal with change. Public needs to be included in the decisions about system Public needs to be included in the decisions about system

reliability in times of uncertainty about future supplies.reliability in times of uncertainty about future supplies.

Better Knowledge NeededBetter Knowledge Needed

There is a lot that isn’t known about climate change impacts There is a lot that isn’t known about climate change impacts on municipal supplies:on municipal supplies:• Only limited studies have been done, and even then broad Only limited studies have been done, and even then broad

assumptions have to be made about the local effects.assumptions have to be made about the local effects.• The impacts on hydrology are the most important unknowns The impacts on hydrology are the most important unknowns

that need to be researched, particularly for urban water that need to be researched, particularly for urban water sources.sources.

• Summer climate change impacts on rainfall patterns are not Summer climate change impacts on rainfall patterns are not as well predicted as temperature increases.as well predicted as temperature increases.

• Reliable long term data needs to be collected and available for Reliable long term data needs to be collected and available for analysis.analysis.

• Synergistic effects between flows, fish, flooding, hydro, and Synergistic effects between flows, fish, flooding, hydro, and water demand patterns present a complex picture that needs water demand patterns present a complex picture that needs more study.more study.

• The role of conservation and curtailment need to be better The role of conservation and curtailment need to be better integrated into long term climate change impacts.integrated into long term climate change impacts.

Parting ThoughtParting Thought

We need to be open We need to be open minded to the reality minded to the reality that the future won’t that the future won’t be like our recent be like our recent historic past. We don’t historic past. We don’t need to overreact, but need to overreact, but we need to start now we need to start now to incorporate the to incorporate the flexibility we will need flexibility we will need to deal with the to deal with the impacts of climate impacts of climate change on our water change on our water resources.resources.