Hydrologic History of the Sacramento-San Joaquin Delta · 12 Total Delta Impairments (upstream and...

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Hydrologic History of the Sacramento-San Joaquin Delta

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title

Report of the Board of Commissioners on Irrigation

Deltaca. 1873

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Early Complicated Network

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Became Simple Web Network

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Major Inflows to Delta(monthly average flows in maf/mo)

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Major Inflows to Delta(monthly average flows in maf/mo)

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Major Inflows to Delta(monthly average flows in maf/mo)

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Major Inflows to Delta(monthly average flows in maf/mo)

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Major Inflows to Delta(monthly average flows in maf/mo)

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Impacts on the Delta(annual flows in maf/yr)

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Total Delta Impairments(upstream and exports in maf/yr)

0

10

20

30

40

50

Unimpaired 1949-1968 1986-2005

-33%-48%

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Total Delta Impairments(upstream and exports in maf/yr)

0

10

20

30

40

50

Unimpaired 1949-1968 1986-2005

-33%-48%

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Total Delta Impairments(upstream and exports in maf/yr)

0

10

20

30

40

50

Unimpaired 1949-1968 1986-2005

-33%-48%

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Total Delta Impairments(upstream and exports in maf/yr)

0

5

10

15

20

25

30

35

Unimpaired 1949-1968 1969-1985

An

nu

al V

olu

me

(maf

)

Delta Outflow Exports Delta Use Upstream Effects

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Internal Flow Changes

Sum of Old and Middle Rivers

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

-12000 -8000 -4000 0 4000 8000 12000 16000 20000 24000 28000

Per

cent

Exc

eede

nce

of F

low 1925-2000 Unimpaired

1986-2005 Historical

Natural downstream flows (cfs)Upstream flows

A

B

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Western Delta Salinity

0%

20%

40%

60%

80%

100%

40 50 60 70 80 90 100 110X2 Distance from Golden Gate Bridge (km)

Per

cent

Exc

eede

nce

of X

2 Lo

catio

n

1921-2003 Unimpaired

1949-1968 Historical

1986-2005 Historical

A

B

C

CQ MZ CH CO EM RV

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Water Use Trends(annual flows in maf/yr)

Data courtesy of TNC

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