California Water Challenge Methodology
09/02/2014 Revision
Policy Option
N/A
Description
The estimated 2030
California “Water Gap"
By 2030, the US Bureau of
Reclamation estimates that
California will have an
annual unmet water
demand of almost 4.9
million acre-feet in an
average year, or just over 6
million acre-feet in a dry
year.
Increase
residential
water rates
Reduce demand by 0.438
MAF by raising residential
water rates by an average
of 20%.
Provide
incentives for
residential
conservation
efforts
Reduce demand by 0.274
MAF by offering rebates to
residential water users to
cover approximately half of
the incremental cost
difference for purchasing
highly efficient vs. standard
toilets, showerheads, and
clothes washers, and for
half the cost of faucet
aerators.
Reduce demand by 0.037
MAF by investing an
additional $10 million per
year in education and
outreach programs at the
local, regional and state
level to promote
conservation and other
behaviors to reduce water
use.
Conserve 0.298 MAF of
water by implementing
more efficient irrigation
techniques on irrigated land
devoted to vegetables,
orchards and vineyards in
the Sacramento River, San
Joaquin River, and Tulare
Lake hydrologic regions.
Education &
Outreach
Irrigation
Efficiency
Improvements
Promote
Alternative
Irrigation
Practices
Conserve irrigation water by
applying regulated deficit
irrigation to 50% of the
state’s current almond and
pistachio acreage, resulting
in savings of 0.283 MAF.
Methodology and Sources
Methodology: The 2030 water gap was estimated in a 2008 report by the US Bureau of Reclamation, and represents the
statewide difference between estimated future water needs and water supplies. The gap is estimated separately for each of the
state's 10 hydrologic zones, and by use (Urban, Agricultural, and Environmental). Excess supplies for a specific use in any region
cannot be used to meet excess demand within that region. All regions are then added together to get the statewide total, but
again excess supplies in one region are not used to offset excess demand in a different region. For the purpose of the Challenge,
the Environmental water gap is added to the Agricultural water gap.
It should be noted that the gap analysis approach is no longer the preferred approach at the California Department of Water
Resources because it runs contrary to DWR’s support of Integrated Water Management objectives, a more complex approach.
The gap analysis is used here, however, to provide the user with a basic understanding of how, even in an average year, future
water supplies are not expected to meet future demands under current policies. It is also useful for providing context for how
effective specific policy options can be for addressing this expected future water shortfall.
Sources:
Water Supply and Yield Study, U.S. Department of the Interior, Bureau of Reclamation, March 2008, pp. A-5 and A-6.
(http://www.usbr.gov/mp/cvp/docs/Water%20Supply%20and%20Yield%20Study.pdf)
Methodology: This analysis estimates the water savings and costs by using the Census Bureau's estimate that there are about
12.5 million households in CA, which in total use about 5.4 million acre-feet of water annually according to California's
Department of Water Resources. The average monthly water charges per household are $42.05 in 2013 dollars as reported in a
2006 survey by Black and Veatch, adjusted to 2013 dollars using the CPI. This implies total statewide annual residential water
charges of $6.3 billion. The same 2006 survey also found that 93% of California's water bills include a fixed component and either
a uniform or tiered volumetric component, with the average water bill having 35% of the charges from fixed costs and 65% from
volumetric charges. Studies on the elasticity of demand for water show an average price elasticity of -0.384, indicating that a
20% average increase in rates would result in a 7.7% decrease in water use, or 0.438 million acre-feet annually. We assume the
fixed component of water charges would not change, while the variable component would go up 20% and result in 7.7% less
water being used for a net statewide increase in water charges of $756 million annually. This translates to an average monthly
increase of about $5 per month per household.
Sources:
DWR 2013 Water Plan, Vol 3, Ch 28. (http://www.waterplan.water.ca.gov/cwpu2013/)
2006 California Water Rate Survey, Black and Veatch (http://www.kqed.org/assets/pdf/news/2006_water.pdf)
Dale, Larry, S. Fujita, F. Vasquez, Mithra Moezzi, Michael Hanemann, S. Guerrero, and L. Lutzenhiser. Price impact on the demand
for water and energy in California Residences, California Climate Change Center (2009).
(http://webarchives.cdlib.org/wayback.public/UCGIL_ag_1/20100407220043/http://www.energy.ca.gov/2009publications/CEC500-2009-032/CEC-500-2009-032-D.PDF)
Bureau of Labor Statistics, CPI. (http://www.bls.gov/cpi/cpid1401.pdf)
Census Bureau data. (http://quickfacts.census.gov/qfd/states/06000.html)
Methodology: This policy option is based on a 2010 study from the Pacific Institute. Using the analyses presented in that report,
we estimate the conservation incentives will result in the replacement of 3.5 million toilets with high-efficiency models via $25
rebates, the installation of faucet aerators and showerheads in 3.5 million homes via rebates of $4 and $10 respectively, and the
installation of 425,000 high-efficiency clothes washers via $125 rebates. The total cost of the program is estimated to be just
over $556 million, but the costs would be financed over 20 years at a rate of 5% for an annual cost of $45 million.
Sources:
Cooley, Heather, Juliet Christian-Smith, Peter H. Gleick, Michael J. Cohen, Matthew Heberger, Nancy Ross, and Paula Luu,
California’s next million acre-feet: saving water, energy, and money, Pacific Institute, Oakland, September (2010).
(http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.172.6926&rep=rep1&type=pdf)
Appendices: (http://www.pacinst.org/reports/next_million_acre_feet/index.htm)
Methodology: This alternative would provide an additional $10 million per year on educational programs beyond what is
currently budgeted. While the impact of any particular education program is highly variable and difficult to quantify, this
analysis assumes a cost of $1,348 per AF conserved, a figure estimated in the Colorado Springs Utilities’ 2008-2012 Water
Conservation Plan. For our analysis we assume this program will spend $50 million total ($10 million per year for 5 years), and
that the conservation savings will be permanent and additive; thus, the final cost/AF is estimated to be considerably lower.
Sources:
DWR 2013 Water Plan, Vol 3, Ch. 29 (http://www.waterplan.water.ca.gov/cwpu2013/)
2008–2012 Water Conservation Plan, Colorado Springs Utilities. Colorado Springs, CO. January 30, 2008.
(https://www.csu.org/CSUDocuments/waterconservationplan.pdf)
Methodology: This analysis is based on a 2010 study by the Pacific Institute. That study proposed that 424,000 acres of Central
Valley cropland devoted to vegetables, orchards and vineyards could adopt more efficient irrigation techniques, with land
currently using flood irrigation upgraded to more efficient sprinkler irrigation, and acreage irrigated with sprinklers upgraded to
the most efficient micro or drip irrigation. Ten percent of orchard and vineyard acreage and fifteen percent of vegetable acreage
remains flood irrigated in this proposal. The costs are expressed as annualized capital costs plus annual operation and
maintenance costs. This analysis expands the original proposal by an additional 25% and assumes the same cost structure would
apply to the additional acreage.
Sources:
Cooley, Heather, Juliet Christian-Smith, Peter H. Gleick, Michael J. Cohen, Matthew Heberger, Nancy Ross, and Paula Luu.
California’s next million acre-feet: saving water, energy, and money, Pacific Institute, Oakland, September (2010).
(http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.172.6926&rep=rep1&type=pdf)
Appendices: (http://www.pacinst.org/reports/next_million_acre_feet/index.htm)
Methodology: This analysis follows a 2010 report by the Pacific Institute. That report included a proposal to apply regulated
deficit irrigation to 30% of the state’s current almond and pistachio acreage, resulting in 20% applied water savings over
conventional irrigation techniques. The costs are expressed as annualized capital costs plus annual operation and maintenance
costs. This proposal applies the same methodology but assumes 50% of the almond and pistachio acreage would be converted to
regulated deficit irrigation rather than the 30% proposed in the original study.
Sources:
Cooley, Heather, Juliet Christian-Smith, Peter H. Gleick, Michael J. Cohen, Matthew Heberger, Nancy Ross, and Paula Luu.
California’s next million acre-feet: saving water, energy, and money, Pacific Institute, Oakland, September (2010).
(http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.172.6926&rep=rep1&type=pdf)
Appendices: (http://www.pacinst.org/reports/next_million_acre_feet/index.htm)
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California Water Challenge Methodology
09/02/2014 Revision
Policy Option
Description
Methodology and Sources
Irrigated Lands
Retirement
Reduce demand by 3.906
MAF by funding the
retirement of irrigated
farmland in the San Joaquin
Valley that has been
identified as either
currently having or
potentially having drainage
problems.
Seawater
Desalination
Increase water supply by
0.54 MAF by completing all
of the 17 seawater
desalination plants
currently proposed along
the California and Mexico
coast that are designated
for California water
deliveries.
Produce an additional 0.023
MAF of water through the
installation of 1,000
dewvaporation facilities
throughout the state, each
with a capacity of 20,000
gallons per day, at an
annual cost of $9.72 M.
Produce an additional 0.400
MAF of water through the
expansion of cloud seeding
projects throughout the
state.
Produce an additional 0.100
MAF of water by
transporting fresh water in
waterbags from coastal
areas with water surpluses,
such as Washington State or
British Columbia, to
California coastal
communities in need of
water, such as Monterey or
San Diego, at a cost of $97
million per year.
Increase water supply by
1.2 MAF by investing in
municipal wastewater
recycling for non-potable
uses or indirect potable
uses such as groundwater
recharge.
Reduce residential water
use by 0.045 MAF by
installing one million
residential gray water
systems, which divert
wastewater from clotheswashers, showers and
bathroom sinks to provide
water for landscape
irrigation.
Methodology: This policy option is based on a 2008 report by the Pacific Institute. The analysis assumes the land that is retired
is irrigated farmland that has been identified as currently having or potentially having drainage problems, representing just over
1.2 million acres statewide. The estimates presented here assume approximately half of this land (slightly more than the
irrigated acreage of the Westlands Water District), will be purchased at fair market prices by the state government. The value of
an acre of irrigated farmland in California is currently estimated to be $12,500 by the US Department of Agriculture. The cost
estimates presented here assume most of this land would then be restored to natural habitat, with some leased back to farmers
for dryland agriculture, which requires no irrigation. These lease fees would generate revenues to offset the remediation and
ongoing maintenance costs for the purchased land. The total costs for purchasing the land would be approximately $7.5 Billion,
financed over 20 years at a 5% interest rate for an annual cost of $630 million.
Sources:
Cooley, Heather, Juliet Christian-Smith, and P. H. Gleick. More with Less: Agricultural Water Conservation and Efficiency in
California, Oakland, California: Pacific Institute, September 2008.
(http://www.pacinst.org/wp-content/uploads/2013/02/more_with_less3.pdf)
Land Values: 2013 Summary, US Department of Agriculture (ISSN: 1949-1867), August 2013.
(http://www.nass.usda.gov/Publications/Todays_Reports/reports/land0813.pdf)
Methodology: This analysis is based on work published by the Pacific Institute in 2008 and 2012. Note that the costs presented
here represent the annual costs and include both the financed capital costs to construct the desalination plants and the ongoing
annual operation and maintenance costs, including estimates for the energy required.
Sources:
Cooley, Heather, and Kristina Donnelly. Key Issues in Seawater Desalination in California: Proposed Seawater Desalination
Facilities, Pacific Institute (July 2012).
(http://www.pacinst.org/wp-content/uploads/2013/02/full_report34.pdf)
Cooley, Heather, and Newsha Ajami. Key Issues for Seawater Desalination in California: Cost and Financing, Pacific Institute
(2013). (http://pacinst.org/wp-content/uploads/2013/12/desal-marine-imapcts-full-report.pdf)
Methodology: This analysis is based on the results of a 2008 pilot project study conducted by the US Bureau of Reclamation.
They estimate the capital cost for each plant to be around $112,000 for a total cost of $112 million which, financed over 20 years
at 5%, is just under $9 million per year, plus an additional $733,000 per year in operating costs (including energy).
Sources:
Dewvaporation Desalination 5,000-Gallon-Per-Day Pilot Plant, Desalination and Water Purification Research and Development
Program Report No. 120, U.S. Department of the Interior, Bureau of Reclamation (June 2008).
(www.usbr.gov/research/AWT/reportpdfs/report120.pdf)
DWR 2013 Water Plan, Vol 3, Ch. 32. (http://www.waterplan.water.ca.gov/cwpu2013/)
Methodology: The cost estimates presented here are provided by the Department of Water Resources in their 2013 Water Plan.
The DWR estimates the program expansion would cost $8 million in initial investment costs and $6 million annually and
calculates the average expected cost to be about $22/AF.
Sources:
DWR 2013 Water Plan, Vol 3, Ch. 11. (http://www.waterplan.water.ca.gov/cwpu2013/)
Methodology: This option is described in the DWR 2013 Water Plan as a potential source of water for California coastal
residents. This analysis assumes water is imported into California from Washington State or British Columbia and delivered to
coastal communities such as Monterey or San Diego at prices comparable to the estimated cost of transporting water from
British Columbia to Monterey, CA. This cost is based on a proposal submitted by Terry G. Spragg & Associates, as reported by
Keith Spain in his 2002 Master's Thesis at the Monterey Institute of International Studies.
Sources:
DWR 2013 Water Plan, Vol 3, Ch. 32. (http://www.waterplan.water.ca.gov/cwpu2013/)
Spain, Keith, Recommendations for the U.S. Trade Representative to Negotiate Trade Rules with Canada Governing Bulk Water
Exports, Master's Thesis, Monterey Institute of International Studies (June 30, 2002).
(http://www.commercialdiplomacy.org/pdf/ma_projects/spain_keith.pdf)
Dewvaporation
Cloud Seeding
Waterbag
Transport/
Storage
Technologies
Water Recycling
Household use
of Gray Water
Methodology: The estimates here are taken directly from a 2003 report on water recycling in California that was published by
the Department of Water Resources.
Sources:
Water Recycling 2030: Recommendations of California’s Recycled Water Task Force, Recycled Water Task Force. Sacramento
(CA): California Department of Water Resources, State Water Resources Control Board, and California Department of Health
Services (2003). (http://www.water.ca.gov/pubs/use/water_recycling_2030/recycled_water_tf_report_2003.pdf)
Methodology: The data used for this policy option comes primarily from a study published by Greywater Action, in collaboration
with City of Santa Rosa and Ecology Action of Santa Cruz. This analysis assumes one million new residential gray water systems
will be installed. These systems are known as "Laundry to Landscaping” and result in gray water being sent directly from the
drain hose of the washing machine to the landscape (usually gravity based). This system is currently the most common type and
the cheapest to install, does not alter the existing plumbing of the house, and does not require a permit in California. According
to the Greywater Action report, the cost to install such a system professionally averages about $750 per household plus an
additional $20 per year for professional maintenance, and self-installed systems average only $250, with maintenance
performed by the homeowner. A 2012 survey cited in the report showed that these systems saved on average 14,565 gallons of
water per household per year. This analysis assumes half of the systems will be professionally installed and maintained and the
other half installed and maintained by the homeowner, and also assumes the systems will last 20 years on average.
Sources:
DWR 2013 Water Plan, Vol 3, Ch 3. (http://www.waterplan.water.ca.gov/cwpu2013/)
Water Recycling 2030: Recommendations of California’s Recycled Water Task Force, Recycled Water Task Force. Sacramento
(CA): California Department of Water Resources, State Water Resources Control Board, and California Department of Health
Services (2003).
(http://www.water.ca.gov/pubs/use/water_recycling_2030/recycled_water_tf_report_2003.pdf)
Allen, Laura, Sherry Bryan, and Cleo Woelfle-Erskine. Residential Greywater Irrigation Systems in California: An Evaluation of Soil
and Water Quality, User Satisfaction, and Installation Costs, Greywater Action, in collaboration with City of Santa Rosa and
Ecology Action of Santa Cruz. November 2012, revised September 2013.
(http://greywateraction.org/sites/default/files/GW_Study_revised-2013.pdf)
Page 2
California Water Challenge Methodology
09/02/2014 Revision
Policy Option
Description
Methodology and Sources
Urban
Stormwater
Recovery
Increase water supply by
0.45 MAF by investing the
funds necessary to double
the current stormwater
recovery levels in Southern
California at an annual cost
of $167 M.
Solar Panels
Over California
Aqueduct
Reduce 0.04 MAF of water
losses from evaporation by
covering 400 miles of the
California Aqueduct with
solar panels, which will also
generate clean energy.
Infrastructure
Leakage
Conserve 0.348 MAF of
water through the use of
acoustic leak detection
surveys and other costeffective water delivery
system monitoring
techniques.
Surface Storage
Generate an additional
0.342 MAF of water storage
by constructing the Sites
Reservoir and the
Temperance Flat Reservoir,
two water storage projects
that have periodically been
under consideration in
California.
Coordinated
Surface Storage
and
Groundwater
Management
Generate an additional
0.240 MAF of actively
managed groundwater by
initiating more water
banking programs at an
annual cost of
approximately $26.8 M.
Methodology: According to a 2013 presentation by Richard Atwater, 450,000 AF is currently captured and actively recharged
into Southern California groundwater basins each year, with billions more gallons lost annually due to a lack of stormwater
capture systems. This proposal aims to double the current amount of stormwater capture, assuming that these additional
facilities will have costs comparable to existing Southern California facilities. The annual cost estimates presented here represent
$1 billion in capital costs financed over 20 years at 5%, plus ongoing annual operation and maintenance costs.
Sources:
Southern California Water Committee Stormwater Capture Opportunities, presentation by Richard Atwater, Executive Director of
the Southern California Water Committee (April 24, 2013).
(http://www.socalwaterdialogue.org/calendar/papers/4-24-13/Stormwater-Capture-Opportunities.pdf)
Methodology: This policy option assumes 400 of the 444 miles of the California Aqueduct will be covered by fixed solar panels
mounted on trellises. A 2013 article by Chris Clark estimates that such a program would likely use thin film photovoltaic cells,
resulting in 4,800 megawatt-hours of energy production each day. The US Energy Information Association estimates the March
2014 median cost for electricity in the transportation sector to be 7.55 cents/kWh in California, implying $134 million worth of
electricity generation each year. A July 2013 publication by Lawrence Berkeley National Laboratory and the US Department of
Energy estimates the current installation costs to be about $3/kW for large utility-scale photovoltaic systems such as this one,
though this does not include operation and maintenance (O&M) costs, nor does it take into account the additional costs of
mounting the panels over the aqueduct. To account for these additional costs this analysis assumes a cost of $4/kW, for a total
cost of $4.2 billion which would be financed over 20 years at 5% interest for an annual cost of $339 million. After considering the
$134 million worth of electricity generated annually, this represents a net annual cost of $205 million.
For the water savings, a 2004 report by the National Resources Defense Council and the Pacific Institute says that conveyance
losses on the aqueduct are around 5%, and this analysis assumes half is from evaporation and half from leakage. Based on
studies that show covering such canals with solar panels reduces evaporation by 70%, this analysis assumes that of the 2.3
million acre-feet of water that is conveyed via aqueduct annually, 58,000 AF are lost to evaporation, and the installation of solar
panels would reduce this loss by about 40,000 AF each year.
Sources:
U.S. Energy Information Association, Table 5.6.A. Average Retail Price of Electricity to Ultimate Customers by End-Use Sector by
State. (http://www.eia.gov/electricity/monthly/epm_table_grapher.cfm?t=epmt_5_6_a)
Cohen, Ronnie, Barry Nelson, and Gary Wolff, “Energy Down the Drain,” Water Supply (2004).
(http://www.nrdc.org/water/conservation/edrain/edrain.pdf)
Clarke, Chris, “Could California’s Canals Create Clean Energy?” Rewire, KCET Los Angeles (August 13, 2012).
(http://www.kcet.org/news/rewire/solar/photovoltaic-pv/could-californias-canals-create-clean-energy.html)
Woody, Todd, “Solar on the Water,” The New York Times (April 19, 2011).
http://www.nytimes.com/2011/04/20/business/energy-environment/20float.html?pagewanted=all&_r=0
Barbose, Galen; Naïm Darghouth, Samantha Weaver, and Ryan Wiser, Tracking the Sun VI: An Historical Summary of the
Installed Price of Photovoltaics in the United States from 1998 to 2012, Lawrence Berkeley National Laboratory and Sun Shot (US
Dept of Energy) (July 2013). (http://emp.lbl.gov/sites/all/files/lbnl-6350e.pdf)
Methodology: The data for this policy option comes from a 2010 study by Southern California Edison and a 2007report by the
California Urban Water Conservation Council. This analysis assumes that statewide water audits and subsequent testing and
repair will result in 0.348 MAF of water no longer being lost to leaks between the treatment facility and the customer, at an
average cost of $393/AF, the average of the costs reported in two recent audits, one conducted by the San Francisco Public
Utilities Commission (SFPUC) and one by the Los Angeles Department of Water and Power (LADWP).
Sources:
The Link between Water Loss and Energy Consumption –Southern California EDISON’s Embedded Energy in Water Pilot,
WaterSmart Conference, Las Vegas, NV (2010).
(http://www.watersmartinnovations.com/posters-sessions/2010/PDFs/10-F-1013.pdf)
Methodologies for Water Loss Management and Updated Costs and Benefits for Distribution System Water Loss Management
Programs, California Urban Water Conservation Council (Draft Revision 6, 2 July 2007).
(http://www.cuwcc.org/WorkArea/downloadasset.aspx?id=8820)
Methodology: This analysis follows a 2010 report by the Pacific Institute. This option specifically assumes that the Sites and
Temperance Flat reservoirs will be completed by 2030, providing an additional 184,000 and 158,000 AF of water storage,
respectively. Cost estimates reported in the Pacific Institute's 2010 report are based on USBR estimates that show capital costs
of $3 billion and $3.4 billion for the Sites and Temperance Flat projects respectively, financed over 100 years at 4 7/8%. As the
report’s authors point out, it should be noted that a shorter financing period or higher interest rates could result in higher annual
cost estimates, but for the purposes of this analysis we have used the cost estimates as presented.
Sources:
Cooley, Heather, Juliet Christian-Smith, Peter H. Gleick, Michael J. Cohen, Matthew Heberger, Nancy Ross, and Paula Luu;
California’s next million acre-feet: saving water, energy, and money, Pacific Institute, Oakland (September 2010).
(http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.172.6926&rep=rep1&type=pdf)
Appendices to report: (http://www.pacinst.org/reports/next_million_acre_feet/index.htm)
Methodology: This analysis assumes one or more additional conjunctive management programs will be initiated that are
comparable in scope and cost to the Kern Water Bank, one of the largest such programs currently active in California. Cost
estimates are assumed to be comparable to those of the Kern Water Bank as provided in the 2013 presentation by Jon Parker,
and includes $40 million in capital costs financed over 20 years at 5% plus annual recharge, recovery and O&M costs.
Sources:
DWR 2013 Water Plan, Vol 3, Ch. 9. (http://www.waterplan.water.ca.gov/cwpu2013/)
History of Groundwater Conjunctive Use in Southern California, presentation by Richard Atwater at the Managed Aquifer
Recharge Symposium, Irvine, California (anuary 25-26, 2011).
(http://www.nwri-usa.org/pdfs/AtwaterPresentationfinal.pdf)
Christian-Smith, Juliet, Improving Water Management through Groundwater Banking: Kern County and the Rosedale-Rio Bravo
Water Storage District, Published in California farm water success stories, Pacific Institute, Oakland, CA (2010).
(http://www.pacinst.org/wp-content/uploads/2013/02/groundwater_banking3.pdf)
The Kern Water Bank, presentation at the Butte Water Forum on February 22, 2013 by Jon Parker, General Manager, Kern Water
Bank Authority (accessed 1/20/2014)
(http://www.buttecounty.net/Portals/26/Education/ConjunctiveUse/THEKERNWATERBANKforconjunctiveuse.pdf)
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