11

City of EverettCity of Everett

Water SupplyWater Supply

December 2008December 2008

Everett Public WorksEverett Public Works

22

Everett’s Water SystemEverett’s Water System

33

Everett’s Water Source Everett’s Water Source StorageStorage

Spada Spada Reservoir Reservoir (50 billion (50 billion gallons) with gallons) with Culmback Culmback Dam in the Dam in the forefrontforefront

44

Everett’s Water Source Everett’s Water Source StorageStorage

Lake Lake Chaplain Chaplain Reservoir Reservoir (4.5 billion (4.5 billion gallons)gallons)

55

Everett’s Source at SpadaEverett’s Source at Spada

66

Sultan River – Water Supply Sultan River – Water Supply ChronologyChronology

City of Everett & Snohomish PUDCity of Everett & Snohomish PUD

1917 – 11917 – 1stst Water Right & Diversion Dam #1 Water Right & Diversion Dam #1 1924 – 21924 – 2ndnd Water Right Application Water Right Application 1929 – 31929 – 3rdrd & 4 & 4thth Water Right & Diversion Dam #2 Water Right & Diversion Dam #2 1946 – Storage Right Application #1 (113,700 Ac-Ft)1946 – Storage Right Application #1 (113,700 Ac-Ft) 1954 – 51954 – 5thth Water Right Application Water Right Application 1959 – City/PUD Agreement to share water rights1959 – City/PUD Agreement to share water rights 1960 – Build Culmback Dam – Phase I1960 – Build Culmback Dam – Phase I 1979 – Storage Right Application #2 (153,260 Ac-Ft)1979 – Storage Right Application #2 (153,260 Ac-Ft) 1982 – Build Culmback Dam – Phase II1982 – Build Culmback Dam – Phase II 1982 – Instream Flows Set For Project1982 – Instream Flows Set For Project

77

88

Everett’s Water Supply and Rights Everett’s Water Supply and Rights

Supply YieldSupply Yield Firm Yield = Avg. Annual Withdrawal Available 98% of YearsFirm Yield = Avg. Annual Withdrawal Available 98% of Years

Firm Yield of Sultan Source = Firm Yield of Sultan Source = 200 MGD200 MGDWith Existing StorageWith Existing Storage

Water RightsWater Rights

Existing Water Rights on Sultan =137.5 MGD (QExisting Water Rights on Sultan =137.5 MGD (QAA); 256 MGD ); 256 MGD

(QI)(QI)

Pending Water Right Application: Pending Water Right Application:

QQI I = 200 cfs; if Q= 200 cfs; if QA A = 100 CFS = = 100 CFS = 64.5 MGD64.5 MGD (Est. Q (Est. QAA))

202 MGD202 MGD

99

Climate Change Models General Circulation Models Climate Change Models General Circulation Models (GCM)(GCM)

Warmest(Pessimisti

c)

Warmer

Warm(Optimistic)

1010

Impact on TemperatureImpact on Temperature

1111

Impact on Sultan StreamflowImpact on Sultan StreamflowDHSVM Historic and GCM 2000

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept

Months of Year

Flo

w R

ate

(c

fs)

GISS_2000 ECHAM5_2000 IPSL_2000 DHSVM_Historic Ensemble_Avg_2000

DHSVM Historic and GCM 2025

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept

Months of Year

Flo

w R

ate

(c

fs)

GISS_2025 ECHAM5_2025 IPSL_2025 DHSVM_Historic Ensemble_Avg_2025

DHSVM Historic and GCM 2050

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept

Months of Year

Flo

w R

ate

(c

fs)

GISS_2050 ECHAM5_2050 IPSL_2050 DHSVM_Historic Ensemble_Avg_2050

DHSVM Historic and GCM 2075

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept

Months of Year

Flo

w R

ate

(c

fs)

GISS_2075 ECHAM5_2075 IPSL_2075 DHSVM_Historic Ensemble_Avg_2075

1212

Three ScenariosThree Scenarios

Three operational scenarios were evaluated:Three operational scenarios were evaluated:

Unconstrained Yield Unconstrained Yield (Storage: 153,000 AC-FT)(Storage: 153,000 AC-FT) Yield Constrained by Transmission Upstream Yield Constrained by Transmission Upstream

of Chaplain Reservoirof Chaplain Reservoir (Storage: 153,000 AC-FT) (Storage: 153,000 AC-FT)

Yield Constrained by Hydropower Operations Yield Constrained by Hydropower Operations and Spada Minimum Surface Elevation of and Spada Minimum Surface Elevation of 1,380 ft1,380 ft (Storage: 101,000 AC-FT) (Storage: 101,000 AC-FT)

1313

Impact of Climate Change on Impact of Climate Change on Three ScenariosThree Scenarios

0

25

50

75

100

125

150

175

200

225

250

275

300

2000 2050 2100

Forecast Year

Saf

e Y

ield

(m

gd

)

Unconstrained System Scenario Constrained by Transmission Scenario Hydropower Scenario

Optimistic Forecasts

Optimistic Forecasts

Optimistic Forecasts

Pessimistic Forecasts

Pessimistic Forecasts

Pessimistic Forecasts

1414

Spada Lake Firm YieldSpada Lake Firm YieldResultsResults

24 – 37 % reduction

6 - 13 % reduction

30 - 50 % reduction

1515

1616

0

25

50

75

100

125

150

175

200

225

250

275

300

2000 2050 2100

Forecast Year

Flo

w (

mg

d)

Constrained by Transmission Scenario Annual Water Right Average Day Demand

Optimistic Forecasts

Pessimistic Forecasts

Annual Water Right - Sultan River and Chaplain

Reservoir (137.5 mgd)

2028

2062

Comparison of Existing Conditions and Comparison of Existing Conditions and Projected DemandProjected Demand

Climate Change Impact: 6 - 13 % reduction by Yr 2100

20 Years on Existing Right; 50+ Years on New 20 Years on Existing Right; 50+ Years on New RightRight

1717

Summary of Climate Impact on Summary of Climate Impact on Water SupplyWater Supply

No Impact on Existing Water Right – No Impact on Existing Water Right –

Good for next 20 yearsGood for next 20 years

Firm Yield would be Reduced 6 – 13% Firm Yield would be Reduced 6 – 13% by 2100by 2100

Modification of SPADA Rule Curves Modification of SPADA Rule Curves would probably offset some of this would probably offset some of this impact (To be determined in impact (To be determined in future studies)future studies)

1818

Spada Reservoir Rule Spada Reservoir Rule CurvesCurves

Water Year – July 1 to July 1

December

Ele

vati

on

FT

State 1

State 3

State2

State 4

Flood

Pocket

1919

2020

2121

2222

Questions?Questions?