California s s Water Supplies and Uses

Transcription

1 California s s Water Supplies and Uses Presented to Delta Stewardship Council Presented by Joe Grindstaff September 21 1

2 Place to Place: Most precipitation falls in the mountains in the north and east From 1998 to 25, precipitation runoff varied from 72% to 171% of average SOURCE: 29 California Water Plan Update SOURCE: 2

3 Variability in precipitation Precipitation varies from year to year Supply over 11 year running mean (orange line) remains relatively constant California Statewide Precipitation (Oct-Sep.) 3

4 Federal, State, and local water projects work together to balance supplies and demands The system of reservoirs and canals were built over the last century to store and move the water to users SOURCE: 29 California Water Plan Update 4

5 Redding To meet demands, water supplies are moved south (2 data) 2,1 1, San Francisco 6, Sacramento 465 3,1 1,375 1,27 Delta Watershed (equal to Sacramento and San Joaquin Hydrologic Regions as defined by DWR) Annual Magnitude of Regional Diversion from Within the Delta Watershed (1, af) (Dashed arrows represent return flows after diversion) 2,875 1, Annual Magnitude of Water Directly Diverted from the Delta Watershed (1, af) Annual magnitude of Water Diverted from a Delta Tributary (1, af) 1,3 Annual Magnitude of Significant Transfers and imports Outside the Delta Watershed Los Angeles DWR Hydrologic Region Boundaries SOURCE: Delta Vision Strategic Plan, 28 1,3 San Diego 5,35 5

6 Population centers rely heavily on water imported from other regions of the state = Net Exporters* Net Importers (Percent of Urban and Agricultural Use met by Imports) = Less than 3% = 3-6% = More than 6% Water Basins In-State Flow of Water for Use * While the Colorado River is a net exporter of water within California, its main source of water is imported from the Upper Colorado Basin SOURCE: California Water: An LAO Primer, 28 6

7 8% In-Delta Use, Mostly Agriculture 65% Outflow to Suisun and San Francisco Bays 74% Sacramento River Valley The Delta is at the heart of the California water system 1% Eastside Tributaries/In-Delta Precipitation 16% San Joaquin River 15% State Water Project, Mostly Southern California Urban and Industrial Use 12% Central Valley Project, Mostly Agriculture Los Angeles = Sources of Water Into the Delta = Water Deliveries and Flow Out of the Delta SOURCE: California Water: An LAO Primer, 28 San Diego 7

8 Environmental Water Use (25) 17,8 TAF North Coast 14,8 TAF Sacramento River 45 TAF North Lahontan 1,4 TAF San Francisco 4,8 TAF San Joaquin River 2 TAF Central Coast 2,4 TAF Tulare 9 TAF South Lahontan LEGEND: Million Acre Feet (1, TAF) Hydrologic Region SOURCE: 29 California Water Plan Update 43 TAF South Coast 3 TAF Colorado River 8

9 Agricultural Water Use (25) 66 TAF North Coast 7,9 TAF Sacramento River 44 TAF North Lahontan 9 TAF San Francisco 6,6 TAF San Joaquin River LEGEND: 9 TAF Central Coast 9,9 TAF Tulare 32 TAF South Lahontan Million Acre Feet (1, TAF) Hydrologic Region SOURCE: 29 California Water Plan Update 3,8 TAF 61 TAF South Coast Colorado River 9

10 Urban Water Use (25) 16 TAF North Coast 82 TAF Sacramento River 4 TAF North Lahontan 1,2 TAF San Francisco 66 TAF San Joaquin River LEGEND: 28 TAF Central Coast 71 TAF Tulare 27 TAF South Lahontan Million Acre Feet (1, TAF) Hydrologic Region SOURCE: 29 California Water Plan Update 72 TAF Colorado River 4,1 TAF South Coast 1

11 Environmental, Agricultural, and Urban Water Use Compared (25) 17, North Coast 18, TAF 17, 16, 15, 14, 13, 12, 11, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, SOURCE: 29 California Water Plan Update 1,4 San Francisco 2 9 1, Central Coast 2, TAF 1, 2,4 2, TAF 1, 9, ,8 7,9 82 Sacramento River 1, TAF 9, 8, 7, 6, 5, 4, 3, 2, 1, 15, TAF 14, 13, 12, 11, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 4,8 6,6 66 San Joaquin River 7, TAF 6, 5, 4, 3, 2, 1, ,1 9 South Lahontan 5, TAF 4, 3, 2, 1, , TAF 4 North Lahontan 1, TAF TAF 3 3,8 72 Colorado River 4, TAF 3, TAF 2, TAF 1, TAF TAF Tulare South Coast 11

12 Residential Water Use 1.7 mil 115 gpcd North Coast 165 gpcd gpcd 243 gpcd.1 mil NA 1 North Lahontan 1The North Lahontan Agenda Hydrologic Item 9 Region does not have enough PowerPoint usable data Presentation in the Public Water Systems Survey (PWSS) database to compute for baseline values. 157 gpcd 2.9 mil 174 gpcd Sacramento River gpcd gpcd 237 gpcd LEGEND: Population, millions Hydrologic Region Total Urban GPCD Residential water use, gallons per capita day (gpcd) SOURCES: CA Department of Finance, 26., Report E-4 Population Estimates for Cities, Counties, and State, 21-25, with DRU Benchmark 2x22 Agency Team, 2x22 Water Conservation Plan mil 13 gpcd San Francisco mil 19 gpcd Central Coast 2. mil 159 gpcd San Joaquin River 154 gpcd mil 18 gpcd Tulare 1 18 gpcd 19.6 mil 126 gpcd South Coast mil 176 gpcd South Lahontan gpcd.7 mil 255 gpcd Colorado River 12

13 Urban/agricultural water use increases and available water for environmental use decreases in drier years All values in million acre-feet (171% of normal) (97% of normal) (72% of normal) Total supply (precipitation and imports) Total uses, outflows, & evaporation Net storage changes in state Distribution of dedicated supply (includes reuse) to various applied water uses Urban uses 7.8 (8%) 8.9 (11%) 8.6 (13%) Agricultural uses 27.3 (29%) 34.2 (41%) 33.7 (52%) Environmental water (required instream flows, Delta outflow, and managed wetlands) 59.4 (63%) 39.4 (48%) 22.5 (35%) Total dedicated supply SOURCE: 25 California Water Plan Update 13

14 Annual Statewide Changes in Storage ( ) SOURCE: 29 California Water Plan Update 14

15 Cumulative Statewide Change in Storage ( ) SOURCE: 29 California Water Plan Update 15

16 Cumulative change in Central Valley groundwater storage ( ) 23) SOURCE: Faunt, C.C., ed., 29, Groundwater Availability of the Central Valley Aquifer, California: U.S. Geological Survey Professional Paper 1766, 225 p. 16

17 Balancing water supplies and uses from year to year is becoming more challenging Since 196, the State population has more than doubled Increase of 4,4, people from 2 to 29 Further anticipated growth will create more demand; droughts more difficult to manage California Population in Millions SOURCE: CA Department of Finance, 21 17

18 Balancing water supplies and uses from year to year is becoming more challenging Irrigated agriculture shifting to permanent crops in some areas, changing irrigation demand patterns Water conveyance through the Delta restricted due to environmental concerns Climate change predicted to change precipitation patterns, decreasing snowpack and increasing flood risks 18

19 Colorado River Flows The graph above shows the natural flow record for the Colorado River at Lees Ferry, from The annual flows are shown in blue, a running 1-year average in red, and a cumulative average in green. Keeping in mind that the total allocation of water at Lees Ferry is 16.5 million acre-feet (MAF) per year, and actual depletions (use plus evaporation) are now about 14 MAF annually, several features of the natural flow record are worth noting: The annual flows over the past century have varied by a factor of five, from about 5 MAF (1977) to 25 MAF (1984) The period from had 1-year average flows higher than any other part of the record except the mid-198s The cumulative average annual flow declined from about 17 MAF (averaged from ) to about 15 MAF (averaged from ) The 1-year running average has varied from about 12.4 MAF to 18 MAF--in other words, the decadal-scale variability has been high From 1934 to 1984, the 1-year running average was almost always below 15 MAF The 2-24 drought was the most severe multi-year drought in the record, with an average annual flow of 9.6 MAF over those five years Western Water Assessment 19

20 Predictions are for more decreases in runoff SOURCE: Colorado Water Conservation Board (CWCB) report Colorado Climate Change: A Synthesis to Support Water Resource Management and Adaptation. Oct 28 (available online at: 2

21 Projected changes in annual temperature, northern California SOURCE: California Department of Water Resources, 27. Climate Change Research Needs Workshop 21

22 Average annual snowmelt for Upper Feather River Basin decreases with temperature increases 3 25 Average Annual Snow Water Content (inches) SOURCE: 29 California Water Plan Update Base +1 C (+1.8 F) +2 C (+3.6 F) Air Temperature +3 C (+5.4 F) +4 C (+7.2 F) 22

23 Historical and projected decreasing California snowpack SOURCE: 29 California Water Plan Update 23

24 Australia s experience with declining flows 62 GL Total Annual* Inflow to Perth Dams (mm) 3 GL Annual Total av (338 GL) av (177 GL) av (12 GL) Notes: - A year is taken as May to April - 24/5 inflow to date 15 Sep 4 Source: Water Corporation 11 GL SOURCE: David Downie General Manager, Office of Water State Government of Victoria, Australia 24

25 Australia Lessons Learned 1. Wide community involvement 2. Lowest cost water is existing water supply 3. Environmental sustainability 4. Climate change can happen faster than you expect 5. Federal / State / local co-operation 6. Pricing 7. Institutional structures are critical 25

26 Conclusions Delta has a key place in California s water picture Change is coming, perhaps faster than we think Tough decisions are being made that will lead to different futures 26

27 California s s Water Supplies and Uses Presented to Delta Stewardship Council Presented by Joe Grindstaff September 21 27