This is the sixth post in my series Drought in California. In Part 1: California Climate and Drought, I found that drought is projected to be the “new normal” climate in California. In Part 2: The Status of California’s Current Water Resources, I found that California is already depleting both it’s groundwater and surface water resources. In Part 3: California’s Total Water Deficit, I constructed an overall estimate of California’s future water deficit, concluding that it will be about 25.1 million acre-feet per year, about 39% of California’s current dedicated water supply. In Part 4: The Potential to Procure Additional Ground and Surface Water, I found that a variety of obstacles and problems made it unlikely that California could cover the predicted future water deficit by tapping additional groundwater or surface water resources. In Part 5: The Potential of Desalination, I found that using desalination to cover the projected water deficit was within the realm of conceptual possibility. However, it would involve a massive infrastructure construction program. Whether such a program could be completed within the needed time frame was unknown. Further, desalinating such a large volume of water would have an annual cost roughly equal to 1% of California’s total GDP.
This post will examine the potential for water conservation by limiting population growth and by limiting environmental uses of water. At the beginning of each part, I have noted that there are problems with the type of exercise I’m attempting, and problems with the data and analyses I’m having to use. If you want to read more about them, see the introduction to the series.
The Basics of Water Consumption
Water consumption gets a bit complex, and one needs a little foundation to understand it. The water literature uses several terms to discuss water use. Total supply is all of the water that comes into the state, by whatever route Dedicated supply is that portion of total supply that is available for human use. Withdrawals refer to water taken from the dedicated supply and used for human purposes. Consumptive withdrawals are used in a way that makes the water unavailable for use in the same water basin. Such a use might involve evaporation, conversion to steam that is lost to the atmosphere, or contamination. Non-consumptive withdrawals return the water to the basin in a way that it can be used again. An example might be irrigation water that either sinks into the ground and then into an aquifer that is tapped by wells, or that flows into a collection pond from which it is used again.
In Part 2 of this series I reported that the California Department of Water Resources estimated dedicated supply to be 65.1 million acre-feet in 2001, a dry year. Figure 5b, repeated from that post, shows the uses to which that water was distributed.
(Click on graphics for larger view.)
Total water withdrawals in California during 2005 were about 51.2 million acre-feet per year. About 28% of California water was withdrawn for thermoelectric generation, which parallels findings in other states. Figure 22a shows the amounts by sector, with withdrawals for thermoelectric generation included. Figure 22b shows the same data with withdrawals for thermoelectric generation excluded. With thermoelectric generation excluded, irrigation accounted for about 76% of all water withdrawals in California. Industrial use (including mines) consumed a mere 1%. Domestic withdrawal is water used in homes. The bulk of it is supplied by public water supply companies, but a small amount is self-supplied, as in a home well. Public supply is water delivered by a state certified public water utility. Most of the water delivered for urban use comes from public supply. In 2005 about 57% of publicly supplied water was delivered to homes, with about 43% going to commercial and other uses. (USGS, 2005)
Why have I netted out water withdrawn for thermoelectric generation? Because it is one of those non-consumptive withdrawals discussed above. Nuclear and coal power plants use huge volumes of cooling water. The cooling water is typically returned to the environment. It may cause local problems because it is hot, but it is not usually otherwise polluted. In this sense, it is used, but not consumed.
Could California reduce water consumption by limiting population growth or by limiting the amount of water returned to the environment?
When I constructed an estimate of California’s future water deficit in Part 3, about 3.1 million acre-feet of it was based on population growth. Should the population stop growing, it would reduce the projected deficit by that much. Figure 23 shows California’s decadal population growth rate in blue, and the USA’s in red. California’s rate of growth has declined over time, and between 2000 and 2010, California’s population grew 10%, the same as the USA as a whole. (U.S. Census Bureau (a), U.S. Census Bureau (b))
To conserve water, California could enact policies to reduce, halt, or reverse population growth. The idea would likely encounter significant resistance, however. Businesses and governments generally assume population decline to be socially and economically destructive, and over the last several decades several countries around the world have taken steps to reverse slowing rates of population growth because of these concerns. (Coleman and Rowthorn, 2011) In addition, policies to limit population growth fairly and equitably would be complex to devise. Some policies, such as the one child policies in China and India, have been oppressive, if not brutal.
It seems unlikely that California will voluntarily enact policies to intentionally limit population growth; it would be extraordinarily controversial. Besides, only 12% of the projected water deficit was based on population growth, and limiting population would do nothing to address the remaining 88%.
I personally believe, however, that the projected water deficit facing California will cause an involuntary reduction in California’s population. I believe that California will become a much less desirable place to live or to locate a business. There will be a net outmigration, just as there was a migration out of the Midwest during the Dust Bowl. This possible scenario will be discussed in more detail in a coming post.
Returning Water to the Environment
The estimate of dedicated supply (65.1 million acre-feet, see Part 2 of this series) is larger than the estimate of net withdrawals by 28 million acre-feet. That’s a lot of water! There are several reasons for the difference. First, supply is different from consumption; the estimates are constructed using entirely different data sets. You wouldn’t expect them to agree perfectly. Second, dedicated supply was estimated for 2001, while withdrawals were estimated for 2005. While both were dry years, it is likely that the total supply was different, and that affected both dedicated supply and withdrawals. Most important, however, is that 35% of the dedicated supply was returned to the environment for environmental remediation purposes. The supply data from the California Department of Water Resources included this water, but the USGS data on withdrawals did not.
From time-to-time I read a proposal that to solve the water deficit, California should simply stop using water for environmental purposes. Of California’s 65.1 million acre-feet of dedicated supply in 2001, some 22.4 million acre-feet of it were used for environmental purposes. That is close to being enough to cover the future deficit I projected.
There would be problems with this proposed solution, however. For instance, the largest single environmental return is water diverted into the San Francisco Bay Delta. In their natural states, the Sacramento and San Joaquin Rivers provide sufficient flow of fresh water through the delta into San Francisco Bay to prevent ocean water from the bay from intruding into the delta. However, so much water has been diverted from these streams that ocean water threatens to intrude. The water in the California State Water Project that is destined for Southern California is discharged into the delta by the Sacramento River, flows across the delta, and is sucked up by huge pumps on the other side, lifting it into the California Aqueduct, and sending it south. If water were not returned to the delta, salt water would contaminate the water destined for Southern California. Even with water returns, the drought has reduced water flow through the delta to the point that the California State Water System is having to construct an emergency barrier in the delta to prevent salt intrusion. (California Department of Water Resources, 5/29/15)
The situation with the delta is an example of a general principal: water returned to the environment is not wasted, it is used to prevent serious environmental damage. Now, there are places around the world where people have chosen to proceed with unwise water diversions, and they have devastated the environment as a result. Perhaps the Aral Sea is the most dramatic example. Once the world’s fourth largest lake, it has been reduced by water diversion to a small fraction of its former extent. The entire region’s climate has been adversely effected, thousands of square miles of barren salt flats have been created, the regions economy has been devastated, and Kazakhstan has begun an expensive emergency program to try to restore the sea. It has been called one of the world’s worst environmental disasters. (Wikipedia, Aral Sea)
California already over-withdraws water from its rivers, causing environmental damage. Would the state choose to turn itself into another Aral Sea? Would it be allowed to do so? I doubt it. I do not believe that significant additional water can be obtained by taking it from the environment.
Thus, it seems unlikely that California will pursue a policy to voluntarily and intentionally limit population. And it seems clear that California cannot pursue a policy of withdrawing additional water from the environment without serious environmental harm. “Environmental harm,” of course, is a euphemism for some really unpleasant stuff, as they found out around the Aral Sea.
This post was corrected on 8/8/15 to correct an error in Figure 22b.
California Department of Water Resources (b). California State Water Project Water Supply. Webpage accessed 5/21/2015 at http://www.water.ca.gov/swp/watersupply.cfm.
California Department of Water Resources. 5/29/15. Emergency Drought Barrier Nears Completion. News release viewed online 6/12/15 at http://www.water.ca.gov/news/newsreleases/2015/052915.pdf.
Coleman, David, and Robert Rowthorn. 2011. “Who’s Afraid of Population Decline? A Critical Examination of Its Consequences.” Population and Development Review. (37), Issue Supplement s1, 217-248. Retrieved online 6/6/15 at http://www.oisp.ox.ac.uk/fileadmin/documents/PDF/WP57_Who_s_afraid_of_population_Decline__by_David_Coleman_and_Robert_Rowthorn.pdf.
NASA. 2005. Sacramento River Delta. Earth Observatory, 12/2/2005. http://earthobservatory.nasa.gov/IOTD/view.php?id=6070.
U.S. Census Bureau (a). Part II. Population of the United States and Each State: 1790-1990. http://www.census.gov/population/www/censusdata/Population_PartII.xls.
U.S. Census Bureau (b). Table 1. Intercensal Estimates of the Resident Population for the United States, Regions, States, and Puerto Rico: April 1, 2000 to July 1 , 1010. http://www.census.gov/popest/data/intercensal/national/nat2010.html.
USGS. Estimated Use of Water in the United States. County Level Data for 2005. http://water.usgs.gov/watuse/data/2005.
USGS/NASA. Satellite imagery of the Aral Sea. Visualization by UNEP/GRID-Sioux Falls. Downloaded 6/16/15 from http://na.unep.net/geas/getUNEPPageWithArticleIDScript.php?article_id=108.
Wikipedia. Aral Sea. Viewed online 6/15/15 at https://en.wikipedia.org/wiki/Aral_Sea.
This is the fifth post in my series Drought in California. In Part 1: California Climate and Drought I surveyed the current drought in California and climate projections for the future, finding that drought is projected to be the “new normal” climate in California. In Part 2: The Status of California’s Current Water Resources I found that California is already depleting both it’s groundwater and surface water resources. In Part 3: California’s Total Water Deficit I constructed an overall estimate of California’s future water deficit, concluding that it will be about 25.1 million acre-feet per year, about 39% of California’s current dedicated water supply. In Part 4: The Potential to Procure Additional Ground and Surface Water I found that a variety of obstacles and problems made it unlikely that California could cover the predicted future water deficit by tapping additional groundwater or surface water resources.
In this post, I will explore whether California could use desalination to cover some or all of the projected future water deficit. A report by the National Academies of Sciences concludes that desalination is likely to have a niche in the national water management portfolio of the future. The size of the niche, however, depends on a host of complicated and locally variable social, economic, environmental, and political factors. Thus, this post will be a bit lengthy and technical: my apologies in advance. I have noted with each post in this series that certain limitations and problems apply to the data and analyses used. They apply to this post, as well. You can read about them in the introduction to the series.
Three main problems hold the potential to limit California’s use of desalination: boron, the power infrastructure required, and the cost.
Boron is a naturally occurring chemical element that is present in ocean water. In normal doses, it is harmless. Desalination, however, concentrates it. Desalinated seawater typically exceeds EPA and WHO guidelines for exposure. Desalinators would need to reduce the concentration of boron to acceptable levels. In addition, little is known about long-term exposure to boron at low levels. Research to explore those effects is needed, but presumably it would not occur, and perhaps could not occur, until desalination plants were already constructed and the population exposed. (Committee on Advancing Desalination Technology, 2008)
Whether California would need to address the problem of boron, and how it might do so, is unknowable at this time.
The Amount of Power Required
Desalinating salt water uses a process called reverse osmosis. The salt water is pushed through a series of filters that are so fine that they filter out the salt molecules, but allow the water molecules to pass. It can be accomplished for as little as 3.4 – 4.5 kWh/cubic meter. (Committee on Advancing Desalination Technology, 2008) In Part 3 of this series, I projected that California’s future water deficit would be 25.1 million acre-feet. At 3.5 – 4.5 kWh/cubic meter, the total amount of energy needed would be 105-139 billion kWh per year.
(Click on graphics for larger view.)
California would need to construct the additional generating capacity to provide the power. I will look at three technologies for generating the necessary power: nuclear, natural gas, and solar.
.The rated output of the nuclear power stations currently operating in the United States is 502 – 3,937 MW. (Energy Information Administration, “How Much Electricity Does a Nuclear Power Station Generate?”) If they operated at full capacity 100% of the time, their annual output would be between 4.4 and 34.5 billion kWh per year. Thus, the energy required to operate the desalination plants could be obtained from 3 large nuclear generating plants, or more smaller ones.
It seems unlikely that new nuclear energy facilities would be constructed in California, however. The problems associated with them are notorious, ranging from storage of nuclear waste to interminable delays and cost overruns. But in addition to these universal problems, California is seismically unstable. Utilities in California have decommissioned nuclear plants because making them earthquake-proof would have been cost prohibitive. Further, the contemplated nuclear plants would consume 2.5 – 3.4 million acre-feet of water per year. (Jones, 2008) But this whole exercise is about the fact that there already is a water deficit: the needed water would not be available.
The most common type of generating plant in California is natural gas. The largest natural gas power plant in California is rated at 2,484 MW. (California Energy Commission. 2014) If it operated at full capacity 100% of the time, its annual output would be 21.8 billion kWh. Thus, to provide the needed energy would require 4 – 6 natural gas generating plants of this size.
Natural gas power plants don’t create nuclear waste, and they don’t require a great deal of water. They do, however, emit carbon dioxide, which has been identified as the primary cause of climate change. Burning natural gas to create the power for desalination would emit 44 – 59 million metric tons of CO2, an increase of 47 – 87% in California’s current emissions. (California Environmental Protection Agency, 2013) California has been decreasing CO2 emissions. The California Global Warming Solutions Act of 2006 requires a reduction to 1990 emission levels by 2020. A large increase in GHG emissions would be incompatible with this legal requirement, and it would be socially unacceptable given California’s commitment to reduce its GHG emissions.
Here let me comment that to construct coal-fired generating stations would create even more new emissions than would natural gas stations, roughly twice as much. For this reason, it will be assumed to be completely objectionable, and will not be considered further.
The amount of power produced by a solar farm varies according to weather and location. Topaz, one of the largest solar PV stations in the world, occupies 9.5 sq. mi. about 50 miles west of Bakersfield CA, and provided 1.05 billion kWh of electricity in 2014. (Wikipedia, “Topaz Solar Farm”) Solar panels deteriorate over time. The exact rate is uncertain, as solar power is a relatively new technology, and the quality of solar panels has improved over time. (Jordan and Kurtz, 2012) If the modules were to lose 20% of their capacity over 25 years, then the initial capacity of the solar farms would have to be increased by 20% to allow for the loss. Thus, the initial solar power required would actually be 126 – 167 trillion kWh per year, which would require a solar farm 1,139 – 1,507 sq. mi. in size, more than twice the size of the City of Los Angeles.
In addition, solar farms only generate power during the day, while desalination plants run 24 hours a day. Half of the power generated by the solar farm during the day (or more) would have to be stored for use at night.
A few types of grid scale storage have been proposed. Batteries may eventually become the most practical grid scale storage technology, but currently available systems are only able to provide power for up to 2 – 4 hours, and they degrade when put through long daily cycles of full-charge-to-deep-discharge, which is exactly what would be needed to power desalination plants. (Akhil et al, 2013)
Pumped hydro is the only proven technology available, and it is the most utilized grid-scale storage technology. Two reservoirs are constructed, one at a significantly higher altitude than the other. Combination generator–pumps are built between them. To generate electricity, water flows from the higher reservoir to the lower one, turning the generator–pumps to make electricity. To store electricity, it is used to power the generator–pumps to pump water from the lower reservoir to the higher one.
The largest pumped hydro station in the world is the Bath County Pumped Storage Station in Virginia. Its construction took 8 years and cost $1.6 billion ($6.2 billion in 2015 dollars). Its rated generating capacity is 3,003 MW. (Wikipedia, Bath County Pumped Storage Station) Operating at full capacity every night of the year, it would generate 19 – 25% of the power that would be needed. Thus, 4 – 5 pumped hydro generating plants of this size would be required to power the desalination plants.
California contains lots of high mountainous terrain, seeming to offer mountain valleys between which sufficient head could be obtained to build pumped hydro stations equivalent to the Bath County Station. Many prime reservoir location are already occupied, however. The California Department of Water Resources lists over 1,200 named dams within its jurisdiction, and 200 named reservoirs. (California Department of Water Resources 2015c, California Department of Water Resources 2015d). In addition, most of the mountainous territory lies within national parks or national forests. In the past, that has not prevented the construction of dams and reservoirs – many existing ones lie wholly or partially inside federal boundaries. However, national sentiment has changed somewhat, and it would introduce an unpredictable political variable. Because pumped hydro power stations require both an upper and a lower reservoir, 8-10 new reservoirs would be required, together with the dams to impound the water, and the pumping/generating equipment. Proposals to build several additional reservoirs have circulated in California for years, but have not been pursued. The Sites Reservoir, for instance, proposed in the 1980s, has not been pursued (Wikipedia, “Sites Reservoir”). It is not known whether 4-5 additional pumped hydro generating stations would be built, and even if they were, whether they could be built quickly enough to prevent widespread dislocations from water shortages.
Another limiting factor in using solar energy to power the desalination plants would be the availability of solar panels and their limited life expectancy. In 2013, about 38,352 MW (peak output) of new solar energy was installed worldwide. (Wikipedia, Growth of Photovoltaics) However, solar panels operate at less than peak output most of the time. To provide the 105-139 billion MWh needed to power the desalination plants would require an installed capacity of 58,167-76,986 peak MW. (National Renewable Energy Laboratory, PVWatts Calculator) That is 1.5-2.0 times the total world installed capacity in 2013. Now, PV manufacturing capacity is growing all the time, and the envisioned project for California would unfold over multiple years. Still, California would need to access a substantial fraction of the world’s PV production.
The need to access a huge supply of PV panels would be ongoing, not a one-time project, because PV panels degrade over time. The exact rate is a matter of controversy, as solar power is a relatively new technology, and the quality of solar panels has improved over time. (Jordan and Kurtz, 2012) A reasonable assumption, however, seems to be that after 20-25 years, the solar farms would either need to be enlarged to replace the lost capacity, or begin a program of module replacement. Were the solar farms to replace their solar panels, each replacement cycle would require a supply equal to the originally installed supply.
In summary, nuclear power has been judged to be too great a seismic risk in California. It also creates nuclear waste, and it consumes large a large quantity of water, which is not available. Natural gas would be seismically more safe. It would emit millions of metric tons of new carbon dioxide, however. This would be contrary to existing California law, and it would be highly problematic for climate change. It seems potentially possible to build solar farms to power the desalination plants. It would require the construction of solar farms on an almost unimaginable scale, more than 100 times larger than any constructed to date. Simultaneously, it would require the construction of a power storage infrastructure. A significant portion of the world’s production of solar panels would be consumed. Appropriate locations for pumped hydro storage would have to be secured, and the necessary permitting and planning issues resolved. Overall, it would be an immensely huge, complex infrastructure construction project, but not impossible on the face of it.
Because the construction of nuclear and gas-fired power stations were found to be problematic, they will not be considered further. Only solar power will be considered in estimating the costs of desalination.
It may be physically possible to desalinate sufficient water to cover the projected deficit, but are there economic barriers that make it impossible?
Available sources emphasize that various problems limit the ability to derive a reliable estimate of the cost of desalination. To date, most discussions of the cost of desalination have occurred in the context of other available water sources. Desalination may have been judged unfeasible because other water sources were less expensive. That may no longer be the case in California; the lack of other alternatives may make feasible a technology that would otherwise be thought too expensive. Worse, many of the estimates have been net of included subsidies that lowered the cost of the water, they have varied widely in which costs were included and which were not, and they have varied in assumptions about the operating life of the plant and its components. Further, many of the costs were site-specific, and were not be generalizable. (Committee on Advancing Desalination Technology, 2008) For these reasons, it is difficult to construct apples-to-apples comparisons.
Assuming interest rates of 6%, a capital-payback period of 20 years, a $0.05/kWh energy cost, and a consumption of 4.5 kWh/cu. meter of water, the Committee on Advancing Desalination Technology (2008) estimated a total cost of $0.61 cents per 100,000 cubic meters of water. Electrical energy was the highest cost, representing 38% of the total, and annualized capital costs were second highest, at 25%. The levelized cost of solar power, however, is not $0.05 per kWh as assumed in the model, but $0.08 per kWh. (Energy Information Administration, 2015) Adjusting for this difference, the estimated cost of desalinated water becomes $0.75 per 100,000 cubic meters. The estimated water shortfall was 25.1 million acre-feet. Converting that amount to cubic meters, the total cost of the desalinated water would be $23.2 billion per year.
The above estimate uses a levelized cost of solar power, which includes the capital costs of constructing the solar farm. However, the costs of constructing the reservoirs needed for power storage would not be included. The cost of a reservoir is site specific. However, we saw above that the cost of constructing the Bath County Pumped Hydro Storage Station was $6.2 billion in 2015 dollars, and California would need to construct 4 – 5 of them. I will calculate the estimated cost based on 5 reservoirs: even if 4 were sufficient, they would have to be hardened against earthquakes, and would thus be more expensive. This would be a one-time capital cost, not a yearly cost. There would be operating costs, but they are typically low. Thus, if one amortizes the cost at a 5% interest rate over the anticipated life of such a reservoir and power plant, which I will assume would be 20 years at minimum, then the annual cost would be something like $2.4 billion.
Thus, the combined total estimate of the annual cost of desalination would be $25.6 billion dollars.
How should one put that number in context? Below are some comparisons:
- The annual cost of desalination would be equal to 23% of the 2014-15 California state budget.
- The annual cost of desalination would be equal to 1% of the 2013 California GDP.
- The annual cost of desalination would increase the amount Californian’s spent on transportation and water infrastructure by 41%.
To cover California’s projected water deficit using desalination would involve a massive infrastructure construction project. Many potential obstacles, any of which could derail the project, would have to be overcome. The most contentious would likely be the construction of massive power generating facilities, with associated power storage, to power the desalination plants. Nuclear power and natural gas-fired power were thought to be too objectionable. However, the construction of solar farms to power the plants was thought to be within the realm of possibility, at least conceptually. Whether such a project could secure the needed funding, secure the needed land for reservoirs, secure the needed supply of solar panels, and secure the needed public and private will and consensus, is not known. The annual cost of desalination was projected to be about $25.6 billion, roughly equal to 1% of the current state GDP.
In the next post in this series, I will look at some options California may have to conserve water.
Akhil, Abbas, Georgianne Huff, Aileen Currier, Benjamin Kaun, Dan Rastler, Stella Chen, Andrew Cotter, Dale Bradshaw, and William Gauntlett. 2013. DOE/EPRI 2013 Electricity Storage Handbook in Collaboration with NRECA. Sandai Report SAND2013-5131, Sandia National Laboratories.
California Energy Commission. 2014. “Database of California Power Plants. Energy Almanac. http://www.energyalmanac.ca.gov/powerplants.
California Department of Water Resources. 2015c. Dams Within the Jurisdiction of the State of California. Web page accessed on 6/2/15 at http://www.water.ca.gov/damsafety/docs/Jurisdictional2014.pdf.
California Department of Water Resources. 2015d. Reservoir Information, Sorted by Dam Name. Via the California Data Exchange Center. Web page accessed on 6/2/15 at http://cdec.water.ca.gov/misc/resinfo.html.
California Department of Water Resources. 2015e. Dams Under the Jurisdiction of the State of California (map). Web page accessed 6/4/15 at http://www.water.ca.gov/damsafety/images/Dams2.pdf.
California Environmental Protection Agency. 2013. Greenhouse Gas Inventory Data – 2000 to 2012. Accessed online at http://www.arb.ca.gov/cc/inventory/data/data.htm.
Committee on Advancing Desalination Technology. 2008. Desalination: A National Perspective. Washington, DC. National Academies Press. Accessed online at http://www.nap.edu/catalog.php?record_id=12184.
Congressional Budget Office. 2010. Public Spending on Transportation and Water Infrastructure. Washington, DC: Congress of the United States. Accessed online at https://www.cbo.gov/sites/default/files/11-17-10-Infrastructure.pdf.
Energy Information Administration. “How Much Electricity Does a Nuclear Power Station Generate?” Frequently Asked Questions. Web page accessed 8/10/2014 at http://www.eia.gov/tools/faqs/faq.cfm?id=104&t=3.
Energy Information Administration. 2015. “Levelized Cost and Levelized Avoided Cost of New Generation Resources in the Annual Energy Outlook 2014.” Annual Energy Outlook 2015. EIA. http://www.eia.gov/forecasts/aeo/electricity_generation.cfm.
Kershner, Isabel. (2015). “Aided by the Sea, Israel Overcomes and Old Foe: Drought.” New York Times 5/29/15. Accessed online 5/29/15 at http://www.nytimes.com/2015/05/30/world/middleeast/water-revolution-in-israel-overcomes-any-threat-of-drought.html?ref=earth&_r=0.
Jones, Willie. 4/1/2008. “How Much Water Does It Take to Make Electricity?” IEEE Spectrum. Accessed online at http://spectrum.ieee.org/energy/environment/how-much-water-does-it-take-to-make-electricity.
Jordan, Dirk, and Sarah Kurtz. 2012. Photovoltaic Degradation Rates – An Analytical Review. Accessed online 6/3/15 at http://www.nrel.gov/docs/fy12osti/51664.pdf.
National Renewable Energy Laboratory. Undated. PVWatts Calculator. Accesssed online 6/3/15 at http://pvwatts.nrel.gov/pvwatts.php.
San Diego County Water Authority. 2015. Seawater Desalination: The Carlsbad Desalination Project. http://www.sdcwa.org/sites/default/files/desal-carlsbad-fs-single.pdf.
The Topaz Solar Generating Station as Seen from Space. NASA Earth Observatory. http://earthobservatory.nasa.gov/IOTD/view.php?id=85403&src=eoa-iotd.
Wikipedia. “Bath County Pumped Storage Station.” Web page accessed 6/2/15 at http://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Station.
Wikipedia. “Growth of Photovoltaics.” Web page accessed 6/2/15 at http://en.wikipedia.org/wiki/Growth_of_photovoltaics.
Wikipedia, “Sites Reservoir.” Accessed online 6/3/15 at http://en.wikipedia.org/wiki/Sites_Reservoir.
Wikipedia. “Topaz Solar Farm.” Accessed online 6/3/15 at http://en.wikipedia.org/wiki/Topaz_Solar_Farm.
This is the fourth post in my series Drought in California. In Part 1: California Climate and Drought I surveyed the current drought in California and climate projections for the future, finding that drought is projected to be the “new normal” climate in California. In Part 2: The Status of California’s Current Water Resources I found that California is already depleting both it’s groundwater and surface water resources. In Part 3: California’s Total Water Deficit I constructed an overall estimate of California’s future water deficit, concluding that it will be about 25.1 million acre-feet per year, about 39% of California’s current dedicated water supply.
In this post, I will begin to explore whether significant new groundwater or surface water may be available. There are three possibilities: groundwater, surface water, and desalination. At the beginning of each part in the series, I note that there are problems with the data and analyses I’m having to use. If you want to read more about the problems, see the introduction to the series.
The Potential to Procure Additional Groundwater
California has been blessed with significant groundwater resources. Maps of the state show that much of the state, even its desert regions, are underlain by groundwater deposits.Those maps should tell us something, however: California’s groundwater resources have already been discovered and mapped. As discussed in Part 2 of this series, the large groundwater basins have already been overdeveloped and are being depleted. Further, if future precipitation declines as projected, especially the snowpack, less water will be available to recharge the groundwater basins, causing their decline to accelerate. One may wish for the discovery of large, previously unknown, groundwater basins, but it seems unlikely.
Some locations (e.g. Santa Monica) have new treatment equipment that purifies potable water from chemically contaminated groundwater sources. In Santa Monica’s case the city once used water from the Charnock Subbasin, but had to stop when it became contaminated with MBTE. The new equipment is capable of removing the MBTE. Though good for Santa Monica, this does not really represent a new groundwater source, but rather the recovery of one that had been lost. (Santa Monica Public Works, 2015)
In addition, most of these groundwater basins are small. For instance, the Charnock Subbasin is part of the Santa Monica Basin. The safe natural yield of the entire basin is 7,500 acre-feet per year, and the Charnock Subbasin is a only a small part of the whole (See Figure 10). Thus, the increase in yield, though meaningful for Santa Monica, is not meaningful against California’s projected future water deficit of 25.1 million acre-feet per year. (Metropolitan Water District, 2007)
(Click on graphics for larger view).
Another possibility would be to purify brackish or saline ground water sources using desalination technology. Compared to ocean water, desalinating brackish water involves an additional limiting physical and cost factor: desalination leaves behind a concentrated brine residue. At the ocean, the brine can be diluted and discharged back into the ocean, which dilutes it even further. Because brine desalination tends to occur inland, disposing of the residue in an environmentally acceptable manner becomes a much greater challenge. Though methods exist, they are imperfect and costly. (Committee on Advancing Desalination Technology. 2010) Given that California is bordered on one side by the ocean, it seems likely that opportunities for ocean water desalination will be exhausted before desalination of saline ground water would be pursued. Ocean desalination will be discussed in the next post in this series.
The Potential to Procure Additional Surface Water
Another possibility would be to transport additional surface water to California. In 2012, the Governor proposed building additional infrastructure to transport existing water from the San Francisco Bay Delta to Southern California. This is precisely what the Central Valley Project and the California Aqueduct already do. There is already a 5 million acre-feet shortfall at the Delta, however, and the existing projects have already caused extensive environmental harm. Despite the severity of the current drought, opposition has prevented the proposal from advancing.
What about diverting water from untapped rivers and watersheds?
Near the coast of Northern California, the Klamath Mountains are the wettest region of the state, with some locations receiving 100 inches of precipitation per year. This has been an area of interest for decades. In fact, one of the original proposals for the California State Water Project went beyond what actually got built and included damming the Klamath, Eel, Mad, and Smith Rivers and shunting their water through a series of inter-basin transfers into the Sacramento River. (See Figure 11) The combined discharge of the rivers into the Pacific Ocean is about 26 million acre-feet, enough to meet California’s estimated future shortfall if almost all of the water were diverted. (Wikipedia, 2015a)
The project, however, would have required one of the largest engineering projects ever undertaken. In addition, it would have appropriated water from holders with senior water rights. The senior holders are Native American Tribes, and while diverting their water may have been politically acceptable in the early decades of the 20th Century, by the 1950s, it was not. And finally, it would have devastated the rivers, their watersheds, and the communities along them. The proposal was not acceptable, and the rivers were not dammed. Even Los Angeles, the proposed final recipient of the water, opposed the plan. (Wikipedia, 2015b)
Today, such diversion projects are received even more frostily than they were in the 1950s. In fact, these rivers are now under the management of the Federal Government in the National Wild and Scenic Rivers Program. Many states are removing dams from rivers, not adding them. Dam removal has even been planned for the Klamath River, where in 2009, the Federal Government and other interested parties agreed to remove 4 dams. The legal rights of Native Americans and of water rights holders are more firmly established than they were many decades ago. (Hanak et all, 2011, p. 117)
Could water from the Klamath Mountains be diverted to the rest of the state? Though the obstacles seem overwhelming, because of the severity of the crisis, one cannot definitively rule out the possibility. Even if the decision were made to proceed with such a project, however, it would take decades of legal wrangling, planning, and construction. Completion would come too late to prevent widespread disruption from water shortages. Thus, no matter what, diversion of the Klamath Mountain Rivers does not seem like a solution to California’s looming water shortage.
What about other rivers?
The rivers on the western slope of the Sierra Madre Mountains have already been fully tapped. On the eastern slope, the Owens River has already been tapped. The only other river of substantive size is the Truckee River. The river arises as the only outlet of Lake Tahoe, and it flows northeast through Reno, Nevada, to Pyramid Lake, Nevada. In an average year, the discharge of the river at Truckee, California is 681,496 acre-feet per year. But given that drought is projected to be the “new normal” climate in California, discharge in low water years may be more relevant. The average discharge of the Truckee River in the lowest quartile of years is 106,272 acre-feet per year, and the lowest year on record is a mere 23,465 acre-feet. Thus, even if all of the river’s water was diverted, it would make good less than 3% of California’s projected water deficit in an average year, 0.4% of the deficit in a dry year, and 0.09% in years similar to the driest one on record.
Further, as is the case with many western rivers, the water in the Truckee is already over-allocated. It is a principal water source for Reno, Nevada, for agricultural interests along its banks, and for Pyramid Lake. All of these communities would be devastated if the water were diverted. In the current drought, the level of Lake Tahoe has dropped below the natural rim of the lake, and flows into the Truckee River have ceased completely. (Figure 13) For these reasons, it seems unlikely that the Truckee River can become a source of significant new water for California.
The Colorado River is the only river to California’s south. As discussed in Part 2 of this series, it has already been tapped, and its reservoirs are in danger of going dry. No substantive rivers flow into the Pacific Ocean on California’s southwestern coast. The rivers along California’s northwestern coast have been discussed above.
Thus, no additional water seems available from untapped rivers and watersheds along or adjacent to California’s borders.
What about rivers outside of California, such as the Snake River and Columbia River? The Snake River is a tributary of the Columbia, running from near Yellowstone Park in Wyoming, through Idaho, to join the Columbia near Kennewick, Washington. It has a large enough discharge to be of interest, and it passes close enough to California to be of interest. The Columbia River would be a better alternative, however, so I will focus on it. It arises in British Columbia and flows through British Columbia and Washington, where it is joined by the Snake River, before running along the Oregon-Washington border to the Pacific Ocean. It is the third largest river, by volume, in North America. Its average annual discharge is about 192 million acre-feet per year. (Kammerer, 1990) At its closest, it is about 400 miles from the northern terminus of the California State Water Project.
One doesn’t have to be an engineer to imagine how this project would have to work. The Cascade Mountans run north-south along the western side of Oregon from the Columbia all the way to California. The best route for an aqueduct would run along the eastern slope of the Cascades, near the Deschutes River. The water would have to be lifted, then flow by gravity over a very long, gentle descent, as the aqueduct zigzagged along the irregular contours of the land. At Bend, Oregon, the aqueduct would have to turn southeast to find its way through scattered low mountains and high desert basins. There would have to be several lifts along the course of the aqueduct, as even the lowest route climbs almost 5,000 feet before reaching Lake Shasta. The route would be considerably longer than 400 miles because of all the zigzagging. To justify the project, its capacity would have to be a significant portion of California’s projected water deficit, perhaps the entire amount (25.1 million acre-feet per year).
In comparison, consider the California Aqueduct, the largest in California by capacity. It takes water from the San Francisco Bay Delta and transports it 444 miles to the Los Angeles Metropolitan Area. Along the way, it must lift the water a total of 1,926 feet. Its capacity is limited by the canal’s capacity, which is 9.5 million acre-feet per year, and by the capacity of the pumps that lift the water over the mountains, which is about 1.4 million acre-feet per year. The energy used to lift water over these heights is huge: one source estimates that the California State Water Project (the whole system, not just the aqueduct) is the largest electricity consumer in the state, consuming 5 billion kWh of electricity per year, or 2-3% of the state’s entire total. (Cohen, Nelson, & Wolff, 2004). Another source estimates that it requires 3,000 kWh per acre-foot to convey California State Water Project water to the Los Angeles Metropolitan Region. This does not include treatment, distribution, or other processing, it only includes conveying the water. The electricity is consumed by the pumps required to lift the water. (Wilkinson, 2007)
Thus, before even mentioning political and environmental concerns, an aqueduct to divert Columbia River water to California would have to be longer than the California Aqueduct. It would have to lift the water at least 2.5 times as high. And its pumping capacity would have to be almost 18 times larger. Upon arriving at Lake Shasta, the water would then enter the existing water distribution systems (primarily the Central Valley Project and California State Water Project). Their capacity would not be sufficient to handle the increased volume; the entire system would have to be re-engineered and upgraded. Construction of the Central Valley Project began in the late 1930s and construction on the California State Water Project was completed in 1997 – a span of about 60 years (not including planning). Megaprojects of this kind are more complicated and obstructed today than in the past, and upgrades to the current system would have to be accomplished without interrupting the delivery of water. Thus, there is reason to think that constructing a system to distribute water from the Columbia River throughout California would be a huge infrastructure project spanning many decades, perhaps as many as the original construction took.
Such a project would be very costly. The Central Valley Project cost $3.6 billion when it was built (starting in the 1930s), which would represent something like $61 billion in today’s dollars. (Environmental Working Group, 2004) A plan to build infrastructure to transport California State Water Project water around the San Francisco Bay Delta was estimated to cost $25 billion. (Boxall, 2013) Those tunnels represent only a small portion of the whole system. Thus, re-engineering the entire system would likely cost $100 billion or more, and that doesn’t even include building the new aqueduct from the Columbia River to Lake Shasta.
At the same time, additional generating capacity would have to be constructed to power the pumps, and also the transmission lines that would be needed to distribute the power. Currently, even though the California State Water Project is the state’s largest consumer of electricity, power requirements are offset because many of its reservoirs are at altitude, and generate hydroelectric power as they discharge their water. But that would not be the case with the Columbia River, which is near sea level. Given that it takes 3,000 kWh of electricity to move an acre-foot of water over the current system to Los Angeles, and given that the new system would be lifting 25.1 million acre-feet 2.5 times as high, the required electrical power would be at least 188 million MWh. This would require the construction of new generating capacity. Presumably it would have to be renewable power, as nuclear, coal, and natural gas would be objectionable for reasons I will discuss more fully in Part 5 of this series.
Finally, the same legal, political, and environmental issues encountered by the Klamath Diversion proposal would apply to the Columbia River idea. While the coastal regions of both Oregon and Washington receive copious precipitation, their inland regions are semi-arid. Both states are experiencing droughts, and their governors have declared drought emergencies. Oregon and Washington do not necessarily look with sympathy on their profligate neighbor’s water woes.
Megaproposals to divert Columbia River water are not new, actually, but, as one article says, “spokesmen for Washington’s and Oregon’s governors…laughed at the idea.” When the Bureau of Reclamation considered one such proposal in the 1960s, it was so objectionable that Congress passed a law stripping the Bureau of its authority to conduct even preliminary feasibility studies of new water diversion projects without Congress’s approval (not just Columbia River diversions, all diversions). The law effectively gives Washington and Oregon veto authority over any proposal to divert water from the Columbia River. (Fox, 2015)
Thus, it seems unlikely that California can find new groundwater or surface water resources to make an appreciable dent in its projected water deficit. This should not be surprising. California has studied and managed its water resources for many decades. They have already located and exploited every resource they could.
Only one alternative for new water remains: desalination. The next post will look at whether the state can procure significant new water from desalination.
Boxall, Bettina. 5/29/2013. “California Plan to Overhaul Water System Hub to Cost $25 billion.”
Los Angeles Times. http://articles.latimes.com/2013/may/29/local/la-me-delta-cost-20130530.
Cohen, Ronnie, Barry Nelson, and Gary Wolff. 2004. Energy Down the Drain: The Hidden Costs of California’s Water Supply. New York: National Resources Defense Council. Retrieved online 5/28/15 at https://www.nrdc.org/water/conservation/edrain/edrain.pdf.
Committee on Advancing Desalination Technology. 2010. Desalination: A National Perspective. National Academies Press. https://www.nap.edu/download.php?record_id=12184.
Environmental Working Group. 12/15/2004. California Water Subsidies: About the Central Valley Project. Webpage accessed 6/15/2015 at http://www.ewg.org/research/california-water-subsidies/about-central-valley-project.
Fox, Justin. 4/27/15. “William Shatner’s California Pipe Dream.” Bloomberg View. Retrieved online 5/28/15 at http://www.bloombergview.com/articles/2015-04-27/william-shatner-s-california-pipe-dream.
Hanak, Ellen, and Jay Lund, Ariel Dinar, Brian Gray, Richard Howitt, Jeffrey Mount, Peter Moyle, and Barton Thompson. Managing Californias Water: From Conflict to Reconciliation. San Francisco, CA: Public Policy Institute of California. Accessed online 54/28/15 at http://www.ppic.org/main/publication.asp?i=944.
Kammerer, J.C. 1990. Largest Rivers in the United States. USGS. http://pubs.usgs.gov/of/1987/ofr87-242.
Metropolitan Water District of Southern California. 2007. Groundwater Assessment Study, Chapter 4: Groundwater Basin Reports. Retrieved online 5/28/15 at http://www.mwdh2o.com/mwdh2o/pages/yourwater/supply/groundwater/gwas.html#4.
Santa Monica Public Works. 2015. Santa Monica Water Treatment Plant. Web page accessed 5/25/15 at http://www.smgov.net/santamonicawatertreatmentplant.aspx.
Slig, Melissa. 4/9/15. “News Briefs March 13-April 9, 2015.” Moonshine Ink. http://www.moonshineink.com/news/news-briefs-march-13-april-9-2015.
USGS (a). 2015. USGS Surface-Water Annual Statistics for California, USGS 10338000 Truckee R NR Truckee CA. Website accessed 5/25/15 at http://nwis.waterdata.usgs.gov/ca/nwis/annual/?search_site_no=10338000&agency_cd=USGS&referred_module=sw&format=sites_selection_links.
USGS (b). 2015. USGS Surface-Water Annual Statistics for California, USGS 11530500 Klamath R NR Klamath CA> Website accessed 5/25/15 at http://waterdata.usgs.gov/ca/nwis/annual/?search_site_no=11530500&agency_cd=USGS&referred_module=sw&format=sites_selection_links.
Van Horn, David. Barge in the Columbia River Gorge” (photograph). Flickr via Wikimedia Commons. [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)].
Wikipedia. 2015a. California State Water Project. Web page accessed 5/28/15 at http://en.wikipedia.org/wiki/California_State_Water_Project.
Wikipedia. 2015b. Klamath Diversion. Web page accessed 5/25/15 at http://en.wikipedia.org/wiki/Klamath_Diversion.
Wilkinson, Robert. 2007. Analysis of the Energy Intensity of Water Supplies for West Basin Municipal Water District. Report for the West Basin Municipal Water District. Los Angeles, CA: West Basin Municipal Water District. Retrieved online at http://www.westbasin.org/files/general-pdfs/Energy–UCSB-energy-study.pdf.
This post is Part 3 of my series on Drought in California. In Drought and the California Climate, published 2 weeks ago, I reviewed the drought California is experiencing, the state’s historical climate, and projections for the state’s future climate. I discovered that drought is expected to become the “new normal” for the state. In The Status of California’s Current Water Resources, published last week, I surveyed California’s current water resources, discovering that California is already experiencing deficits in both groundwater and surface water. Both groundwater and surface water supplies are being depleted. Unless changes are made, the depletion is projected to continue.
This post attempts to construct a summary total of California’s overall water deficit. The estimate is going to be a very rough, “back-of-the-envelope” exercise, that relies on a number of assumptions that may, or may not, be correct. Nevertheless, such an estimate is needed in order to evaluate potential measures to procure additional water supplies and to conserve existing ones. There are surprisingly few published estimates out there. They are uneven in what they include and omit. Indeed, much of the data and the analysis used for this series have problems and limitations. You can read about them in the introduction to the series.
California’s Total Water Deficit
As noted in the previous post, the total water supply for California has been estimated for wet, average, and dry years. Because climate change is expected to cause drought to be the “new normal” in California, the supply during dry years is the one that should be of most interest to us.
In addition, either the total supply or the dedicated supply can be estimated. The total supply is an estimate of every drop of water that falls on the state as precipitation, every drop that is imported in aqueducts from other states, every drop that is desalinated, and every drop that is pumped out of the ground. The dedicated supply is the portion available for human consumption. The not-dedicated water is not surplus; it recharges aquifers, and supports the plants, animals, and fish that live in California. Thus, it is not an untapped water supply available for humans to grab. The dedicated supply is the estimate that is relevant to these calculations. As noted in the previous post, the dedicated supply of water during a dry year is 65.1 million acre-feet. (California Department of Water Resources (b)).
Table 3 at right shows how the dedicated water supply is used in wet, average, and dry years. The table shows that in dry years, the amount of water distributed by the California State Water Project to agriculture and to urban uses actually increases. But the amount distributed to environmental uses decreases by almost 1/3. This is not difficult to understand: they close the sluice gates. More water is held in the reservoirs and diverted into the aqueducts, less flows into the rivers.
(Click on graphics for larger view.)
California currently derives its water from two primary sources: groundwater and surface water. Groundwater comes from aquifers. The largest and most important fresh water aquifer in California is the Central Valley Aquifer. Its status was reviewed in the previous post. As it is the most important aquifer, I will let its deficit stand in for the total groundwater deficit, though it is surely an underestimate. Water storage in the Central Valley Aquifer declined by at least 114 million acre-feet between 1962 and 2014. That is about 2.2 million acre-feet per year. Withdrawals would have to be curtailed by that much to stabilize the aquifer. (May, 2015)
An analysis by the Pacific Institute and the National Resources Defense Council estimates that California diverts 5 million more acre-feet from the Sacramento-San Juan watershed than can be sustained, and depletes up to 2 million acre-feet from that watershed’s groundwater supplies. It is not clear how this study’s estimated groundwater deficit overlaps with the Central Valley Aquifer decline estimated above, but I will assume that half of it does, and the Pacific Institute estimate should be adjusted by that amount. Thus, the overall estimated deficit is 6 million acre-feet. (Pacific Institute and the NRDC, 2014)
The EPA estimates that California’s groundwater deficit in 2010 was 2 million acre-feet per year. Given current trends, population growth in California will result in an additional 6.2 million acre-feet deficit in a drought year. The current deficit of 2 million acre-feet appears to overlap with the estimate by the Pacific Institute, and will not be included further in this calculation. The future estimate appears to be an estimate of increased demand caused by the anticipated increase in population. For many years, California’s booming economy has depended on a growing population, and it seems unlikely that economic interests will want to freeze or reduce it. It seems equally unlikely, however, that the trend can continue unchanged. Thus, because population growth may slow, it may be reasonable to reduce the EPA’s estimated deficit. By how much is not clear, but by 50% may be reasonable. That would be 3.1 million acre-feet. (EPA, 2010)
Neither the Pacific Institute estimate nor the EPA estimate attempts to assess the effects of reservoirs going dry, or of a significant decline in the snowpack. Were Lake Mead to go dry, it would interrupt water deliveries from the Colorado River System. Although the intakes for the aqueducts that deliver the water are in Lake Havasu, if Lake Mead were to go dry, it would disrupt managers’ ability to manage the water level in Lake Havasu, uncovering the intakes. The system provides about 4.4 million acre-feet per year to the state, and this would represent an immediate loss of that supply. For Southern California’s metro areas, it would represent a loss of about 23% of their water supply. The loss of one or more of California’s instate reservoirs would be only slightly less catastrophic. I don’t have an estimate of when that might occur, however, so it will not be included in this calculation. Recall from the previous post that even a 25% reduction in water withdrawals still left a 50% chance that Lake Mead would go dry by 2060. Thus, the draw from the Colorado River would need to be reduced by more than that. How much more is unclear, but again, a 50% reduction seems not unreasonable. That would be 2.2 million acre-feet. (Barnett and Pierce, 2008)
In 2015 the California snowpack was only 5% of its historical average. If this were to become the normal occurrence, it would represent an immediate and existential threat to the state. Not only would runoff into the streams that charge California’s man-made reservoirs be reduced, but water seeping into the ground to recharge the aquifers would, also. However, the 2015 snowpack may be a temporary extreme, and it may be better to accept the National Climate Assessment’s projection of an average 40% decline in the water content of the snowpack (discussed in Part 1). That would amount to 11.6 million acre-feet.
It is difficult to know how to combine this information into an overall estimate of California’s looming water shortage. It seems that only the National Climate Assessment anticipates a decline in water supply based on the decline in the snowpack, and none of the estimates discuss the need to reverse the already-occurring depletion of essential reservoirs.
The estimated deficit in the Central Valley Aquifer is 2.2 million acre-feet per year. The Pacific Institute’s estimate for this same region overlaps with this estimate by about 1 million acre-feet per year, but adds surface water deficits. Adjusting the Pacific Institute estimate to reflect the overlap, the deficit is estimated at 6 million acre-feet per year. These two estimates pertain to only part of the state, the Central Valley. However, that watershed is by far the state’s largest and most important. The aquifer and the two rivers there are the largest within the state. A large part of the excluded area is very dry, and water from the two Central Valley rivers is delivered far and wide across the state. Therefore, these two estimates appears to be a minimum, but reasonable starting point. The EPA’s estimate (adjusted to remove overlap with the Pacific Institute and to anticipate a reduced rate of population growth) represents the increase in demand that would come from an increase in population. It would be 3.1 million acre-feet per year. To prevent Lake Mead from going dry would require a 2.2 million acre-feet reduction. Finally, by far the largest of these potential water deficits would be the decline in the snowpack, which would be 11.6 million acre-feet. (U.S. Global Change Research Program, 2014)
Combined, they sum to a total water deficit of 25.1 million acre-feet, about 39% of California’s dedicated water supply in dry years. Thus, I estimate that to remove its future water deficit, California will need to increase supply and/or reduce demand by more than 1/3.
This estimate is much larger than currently published estimates. The primary reason is that I have included both population growth and the projected effects of climate change. If population growth and climate change trends were to change, it would impact the estimate. In addition, though I remarked on the limitations of this analysis at the beginning, I feel I should restate that the analysis relies on a number of assumptions that may or may not be correct, and on data that is far from perfect.
California can contribute to minimizing the impacts of climate change, but no single state is in control of climate change. California will have to adjust. The estimate constructed above provides one perspective on just how much adjusting they will have to do. In coming posts, I will explore potential strategies for increasing water supply and/or reducing demand.
Barnett, Tim, and David Pierce. 2008. “When Will Lake Mead Go Dry?” Water Resources Research, 44, W03201. Retrieved online at http://www.image.ucar.edu/idag/Papers/PapersIDAGsubtask2.4/Barnett1.pdf.
California Department of Water Resources (b). California State Water Project Water Supply. Web page accessed 5/21/2015 at http://www.water.ca.gov/swp/watersupply.cfm.
EPA. 2010. “California Water Fact Sheet.” EPA WaterSense. EPA832-F-10-016. http://www.epa.gov/watersense/docs/california_state_fact_sheet.pdf.
May, John. 2015. “The Status of California’s Current Water Resources.” Blog post in the blog MoGreenStats. http://www.mogreenstats.com.
Pacific Institute and the National Resources Defense Council (NRDC). 2014. The Untapped Potential of California’s Water Supply: Efficiency, Reuse, and Stormwater. http://pacinst.org/publication/ca-water-supply-solutions/#issuebriefs.
U.S. Global Change Research Program. 2014. Climate Change Impacts in the United States: The Third U.S. National Climate Assessment. http://www.nca2014.globalchange.gov.
This is Part 2 of a series Drought in California. Part 1, Drought and the California Climate was published last week. The data and the analysis used for this series have some limitations. You can read about them in the introduction to the series.
California’s Overall Water Resources
It is difficult to estimate the total amount of water that could theoretically be available to California. One would have to count every raindrop, snowflake, and droplet of mist that fell on every inch of the state. One would have to include every pond and rivulet across the state, and every pocket of underground water, no matter how hidden. And one would have to include the water imported via aqueduct from outstate.
In addition, the amount available for human consumption, called dedicated supply, is only a portion of the total. The remainder is absorbed by the ground, runs off into streams that flow to the ocean, or evaporates. Historically, the water not used by humans has been considered lost or wasted. However, we now know better. The water that is absorbed by the ground recharges underground aquifers and it is used by California’s plants and animals. The water that flows into streams supports the life along the streams, including fisheries: the Sacramento River used to be one of the larger salmon fisheries on the West Coast. These are all valid and important uses, and you cannot deprive them of water without damaging them.
The California Department of Water Resources estimates California’s water supply in wet, average, and dry years:
Table 1: Summary of California’s Water Supply
1998 (Wet Year) (million acre-feet)
2000 (Avg Year) (million acre-feet)
2001 (Dry Year) (million acre-feet)
|Total Supply (Precipitation & Imports)||
|Dedicated Supply (Includes Reuse)||
Source: California Department of Water Resources.
Because drought is projected to be the “new normal” for California, dedicated supply during dry years is the supply in which we should be interested. That supply is distributed to three broad use categories: urban uses, agricultural uses, and environmental uses (Figure 5b).
(Click on graphics for larger view.)
The first two are self-explanatory. Environmental uses are those uses where water is returned to the environment to restore or prevent damage caused by water withdrawal. An example might be the release of water into a river where the ecosystem has been damaged by water withdrawal.
California’s Groundwater Resources
Groundwater is one of California’s most important water sources. In average years, it supplies about 40% of California’s water, in drought up to 60%. (Pacific Institute and NRDC, 2014) The state is divided into 10 large hydrologic regions, defined by surface water runoff patterns. Underlying each region are dozens of individually named groundwater basins, or aquifers. These vary widely in size.
Only a few of California’s groundwater basins are well enough understood to have estimates of overall storage capacity associated with them. For the most part, the health of the groundwater supply is studied using changes in the water level in the aquifer, and comparing it to the aquifer’s overall depth.
The Central Coast of California, roughly from Santa Barbara to Monterey, is the region most dependent on groundwater: about 83% of demand is met from groundwater resources. It is not, however, the region that uses the most groundwater.
California’s Central Valley is a broad, flat valley about the size of West Virginia (see Fig. 6). It runs roughly from Redding in the North to Bakersfield in the south, and from the Sierra Nevada Mountains on the east to the Coastal Ranges on the west. It is the most important agricultural area in the USA, and water from the Central Valley Aquifer is used to irrigate crops. It consists of 3 hydrologic regions: Tulare Lake, the San Juan River, and the Sacramento River. These 3 hydrologic regions comprise by far the largest, most abundant, most used, and most studied groundwater supply in California. Approximately 70% of all groundwater extraction occurs in these 3 basins, 35% in the Tulare Lake basin alone. (California Department of Water Resources, 2003)
Withdrawals have greatly exceeded recharge, and the level of the aquifer has dropped. This has resulted in water shortages and land subsidence (see Figure 7). Aquifers are like lakes – they have irregular bottoms, so if the level drops too low, some regions are left high and dry. If subsidence occurs, it can cause several problems. Roads and foundations may buckle, irrigation canals through which the water flows downhill may suddenly find themselves going uphill instead, and worst of all, the ground may compact. If the ground compacts, the aquifer may lose some or all of its ability to recharge with water. Where this occurs, the result is a permanent loss of the aquifer.
For a period during the late 20th Century, this trend was arrested, but it is recurring now, with the land subsiding a foot a year between 2003-2010. Figure 8 shows the change in the amount of water stored in the Central Valley Aquifer through 2003. The dark blue line shows the total aquifer, the other colors show various parts of it. Through 2003, the overall decrease was almost 50 million acre-feet. (Faunt, 2009)
The current drought has forced the California Water System to restrict deliveries of surface water to agriculture, so well pumping has accelerated. One source estimates that the Sacramento and San Joaquin River Valleys, about 2/3 of the Central Valley, lost 30 cu. km. of water between 2003 and 2010, years not included in the chart. (Farmigleietti, 2014) These regions had not lost significant water storage prior to 2003.
Yet another study suggested that between 2011 and 2014 another 34 million acre-feet of groundwater has been lost in the Sacramento and San Joaquin Valleys. Thus, the total loss is over 114 million acre-feet. For comparison sake, the storage capacity of Lake Mead is about 28 million acre-feet, so the total amount is equal to more than 4 Lake Meads. Wells are having to be deepened; permits for well drilling tripled in one county. Well depths are now commonly over 1,000 feet. (Howard, 2014)
I have been unable to find estimates of how much water is left in the Central Valley Aquifer. If unlimited withdrawals continue, at some point the aquifer will be exhausted. For most of its history, California did not limit the amount of water that a farmer could withdraw (most other states do). However, on 9/18/14, California adopted the Sustainable Groundwater Management Act of 2014, and it went into effect 1/1/2015. The act does not require groundwater sustainability until 2040. Will the aquifer last that long? How much damage will it sustain? I don’t think anybody knows.
Note that this aquifer supplies not only agriculture, but also many of the cities in the Central Valley, home to about 6.5 million people.
California Surface Water Resources
In far Northern California rainfall occurs much of the year. The rest of California depends on snowpack for its surface water. Snowmelt drains into rivers, and the rivers run into huge reservoirs, from which water is distributed as needed. There are several water distribution systems. For instance, San Francisco brings water from the Hetch-Hetchy Reservoir inside Yosemite National Park through the Hetch-Hetchy Aqueduct to the Bay Area. Los Angeles brings water in the Los Angeles Aqueduct from the Owens River (on the east side of the Sierra Nevada Mountains, as far north as Mono Lake) all the way to Southern California. And a consortium of Southern California water systems bring water from the Colorado River through the Colorado River Aqueduct to the large metropolitan areas of Southern California.
The largest two water systems, however, are the Central Valley Project and the California State Water Project (shown on the map at right, the Central Valley System in purple, the California State Water Project in orange). The Central Valley Project, owned by the Federal Government, stores water in the Trinity and Lake Shasta reservoirs in far northern California (top purple arrow on the map), and distributes it throughout the Central Valley, as far south as the town of Mendota (bottom purple arrow). The Central Valley Project was intended to prevent flooding along the Sacramento and San Juan Rivers, and to provide irrigation for agriculture. The California State Water Project collects its water in the Feather River watershed in northeastern California, stores it in Lake Oroville Reservoir (top orange arrow on map), discharges it into the Sacramento River, transfers it to the California Aqueduct, glides it 250 more miles south, lifts it over the Tehachapi Mountains, and finally distributes it to the Los Angeles Metropolitan Area (bottom orange arrow on map).
The amount of water delivered by the systems is limited by the amount of water available for diversion and by the capacity of the aqueducts. On the California Water Project, the limit is the lift capacity over the Tehachapi Mountains, which is 1,926 cubic feet per second (California Department of Water Resources (c)) The Central Valley Project is more distributed around the state, but on the Delta-Mendota Canal, the canal that distributes northern California water to the southern Central Valley, capacity is 4,600 cubic feet per second.
The drainage area that provides surface water to California covers much of the western United States. It includes the entire state of California, of course. But it also includes the area drained by the Colorado River, as shown in Figure 9 at right.
There are some basic problems here. The first is sharing. Water from the Colorado River is used by people in Colorado, New Mexico, Utah, Nevada, Arizona (all the way to Tucson), Mexico, and California. The water allocation scheme was developed in 1922. California gets the largest share. Suffice it to say that those other people don’t always like doing without water so California can have more.
The sharing problem is not unique to the Colorado River. The Owens River Valley (the eastern slope of the Sierra Nevada as far north as Mono Lake) supplies virtually all of its water to Los Angeles. Water from Northern California (think Lake Shasta) is transported all the way to Southern California. Hetch Hetchy Reservoir was built inside Yosemite National Park to provide water to San Francisco, flooding a valley that was said to rival its more famous sister to the south. All are controversial. Still, these are political problems and could theoretically be solved by people willing to compromise.
More difficult to solve is the fact that tremendous development has occurred, and the demand for water outstrips the supply. Since 1922, when the Colorado River Compact was established, California’s population has grown from about 3.5 million to about 37 million. Arizona’s has grown from about 0.3 million to about 6.4 million. Las Vegas has grown from about 2,000 to about 2 million. There just isn’t enough water, at least given current usage patterns.
At right is a repeat of Figure 4 from the previous post, showing the annual Palmer Hydrological Drought Index for California. You can see that the first two decades of the 20th Century were the wettest in the record. This was true for the entire western USA, not just California. That means that Colorado River allocation levels were based on abnormally wet years; they overestimated the amount of water reliably available from the river. Since then, the region has dried, and the water available from the river has decreased. Combined with the tremendous surge in demand, it means that demand exceeds supply.
To get a rough estimate of the current state of California’s surface water resources, one way is to look at reservoir levels. The major reservoirs on the Colorado River are Lake Powell and Lake Mead, which together account for the vast majority of water stored on the Colorado River System. Recall that the Colorado River provides water for much of Southern California, including the agricultural area of the Imperial Valley.
Much has been made of the “bathtub ring” at Lake Mead. The water level there has dropped 142 feet (see photo at right) and is at the lowest level since Lake Mead first filled. It is currently at 39% of full pool (5/12/2015). This represents 52% of Lake Mead’s average historical storage on this date. (Lake Mead Water Database, 5/12/2015) Lake Powell fluctuates with the snowmelt, being fullest in early summer, emptiest in late winter/early spring. Currently, it is at 44% of full pool, which represents 59% of average historical storage for this date. (Lake Power Water Database, 5/12/2015)
A system of reservoirs inside California impounds and stores water from California’s rivers. California’s largest “reservoir” is its mountain snowpack, which stores water during the winter months , and then releases it as the snow melts during the spring and summer. The snowpack accounts for fully 30% of California’s water, or 29 million acre-feet of California’s dedicated water supply. The snowpack is typically at its deepest around April 1 each year. As noted above, however, climate change is predicted to reduce the water content of the snowpack by 40%. The situation this year (2015) is much worse than predicted, however. On April 1, the water content was 5% of its historical average for that date. Thus, as the dry season begins, California’s largest “reservoir” is 95% empty. (California Department of Water Resources, 2015)
Table 2: Current Conditions on 14 Major Reservoirs (5/12/2015).
|Reservoir (largest to smallest)
||% of average historical storage on this date
||% of average historical storage on this date
Lake Mead data from the Lake Mead Water Database. Lake Powell data from the Lake Powell Database. Other reservoir data from the California Data Exchange Center – Reservoirs.
The largest man-made reservoir in California is Lake Shasta, about 1/6 the size of either Lake Mead or Lake Powell. California’s man-made reservoirs are also very low compared to historical averages for this date. Table 2 summarizes the current percent of average historical storage on May 12, 2015 for the two Colorado River reservoirs and the 12 largest California reservoirs.
Climate projections suggest that, while the current drought in California may be especially severe, the drought in California is likely to become a long-term normal pattern. If it does, how long before the reservoirs run dry? I don’t know. But a scientific paper from the Scripps Institution of Oceanography predicted a 50% chance that Lake Mead would be empty by 2021, and a 75% chance by 2040. (See Figure 8) If water deliveries were reduced by 10%, then the 50% probability of going dry would be postponed until about 2035. If deliveries were reduced by 25%, then the chance of going dry would be postponed until about 2060. Be sure to understand the implications here: water withdrawals from the Colorado system could be reduced by 25%, a huge reduction, and the reservoir would still have a 50% chance of going dry in the middle of the century.
The next post in the series will try to develop an estimate of the overall average annual water deficit that will be faced by California later this century.
California Department of Water Resources. 2015. Sierra Nevada Snowpack Is Virtually Gone; Water Content Now Is Only 5 Percent of Historic Average, Lowest Since 1950. News release published 4/1/2015. http://www.water.ca.gov/news/newsreleases/2015/040115snowsurvey.pdf.
California Data Exchange Center – Reservoirs. http://cdec.water.ca.gov/cdecapp/resapp/getResGraphsMain.action.
California Department of Water Resources. California State Water Project Water Supply. Webpage accessed 5/21/2015 at http://www.water.ca.gov/swp/watersupply.cfm.
California Department of Water Resources. 2003. California’s Groundwater, Bulletin 118, Update 2003. http://www.water.ca.gov/groundwater/bulletin118/report2003.cfm.
Faunt, C.C., ed., 2009, Groundwater Availability of the Central Valley Aquifer, California: U.S. Geological Survey Professional Paper 1766.
Farmiglietti, Jay. 2014. “Epic California Drought and Groudwater: Where Do We Go From Here?” National Geographic News Watch: Water Currents. 2/4/14.
Howard, Brian. “California Drought Spurs Groundwater Drilling Boom in Central Valley. National Geographic. 8/16/2014. http://news.nationalgeographic.com/news/2014/08/140815-central-valley-california-drilling-boom-groundwater-drought-wells.
Klausmeyer, Kirk, and Katherine Fitzgerald. 2012. Where Does California’s Water Come From? San Francisco: The Nature Conservancy.
Lake Mead Water Database. Accessed online 5/12/2015 at http://lakemead.water-data.com.
Lake Powell Water Database. Accessed online 5/12/2015 at http://lakepowell.water-data.com.
NASA. 12/16/2014. “Needed: 11 Trillion Gallons to Replenish California Drought.” Nasa Science News. http://science.nasa.gov/science-news/science-at-nasa/2014/16dec_drought.
NASA. 2014. “Satellite Study Reveals Parched U.S. West Using Up Underground Water.” News and Features, Release 14-200. https://www.nasa.gov/press/2014/july/satellite-study-reveals-parched-us-west-using-up-underground-water/#.VVpNrOdpey0.
Pacific Institute and the National Resources Defense Council (NRDC). 2014. The Untapped Potential of California’s Water Supply: Efficiency, Reuse, and Stormwater. http://pacinst.org/publication/ca-water-supply-solutions/#issuebriefs.
USGS. 2009. California’s Central Valley Groundwater Study. Factsheet 2009-3057. http://pubs.usgs.gov/fs/2009/3057.
USGS California Water Science Center. CVHM Numerical Model. Web page accessed 5/20/2015 at http://ca.water.usgs.gov/projects/central-valley/cvhm-numerical-model.html.
USGS Water Science School. Land Subsidence in California. Web page accessed 5/20/2015 at https://water.usgs.gov/edu/earthgwlandsubside.html.
This post is Part 1 of a series on Drought in California. Part 2 will be published next week. The type of analysis I am attempting, and the data I am having to use, have some problems and some limitations. You can read about them in the introduction to the series.
Development in California and in other western states has been possible because of extensive exploitation of water resources. California is in the midst of a severe multi-year drought. Due to climate change, drought is predicted to become the “new normal” for California. Demand for water is already outstripping supply, and if current trends continue, the imbalance will increase.
California will have to develop new water resources and reduce consumption. Desalination looks like the only possible new water resource at this time, but it will come at a significant cost. The combination of increased costs and efforts to conserve water are likely to negatively impact California’s economy and the lifestyle for which it is famous.
California’s agriculture sector will be especially hard hit, resulting in farm failures, unemployment, and dislocations that will be reminiscent of the Dust Bowl, though less severe.
The risk is that the combination of these effects could cause a deflationary spiral to occur in the value of assets located in California. There may be a halt in immigration, and perhaps even a significant outmigration.
Drought and the California Climate
California is experiencing a significant drought. While the current drought is especially severe, there are many indications that drought may not be a temporary condition. The 20th Century was an abnormally wet period for California, and the region may be returning to long-term averages.
(Click on graphics for larger view.)
California is probably the most varied state in the country. It boasts the highest mountain in the contiguous 48 states (Mt. Whitney), and the lowest land location in North America (Death Valley). It is the most populous state in the country, but it also has desert regions where few, if any, people live. It has snowy peaks that in some years receive prodigious amounts of snow, and the driest land in the country.
The wet areas include the North Coast, the Shasta-Trinity Region, and the Sierra Nevada Mountains (marked on Figure 1). They typically receive at least 25 inches of precipitation per year, and in some locations 100 inches or more! Much of Southern California is outright desert, receiving less than 10 inches of precipitation per year (the red areas in Figure 1). The dry regions include significant portions of the Central Valley and the Imperial Valley, two of the state’s most important agricultural areas. These regions are marked in Figure 1.
Exacerbating the dry nature of Southern California is the monsoonal nature of the precipitation. Most of it falls from November through March. From April through November, precipitation in the southern part of the state ranges from about 4 inches (Central Valley) to less than 2 inches (southeastern desert). Such a precipitation pattern can only be survived by humans via access to other sources of water: rivers, lakes, reservoirs, and wells.
Drought is a function of soil moisture. Low precipitation leads to low soil moisture, but so do sunshine and heat. They dry the soil more quickly, leading to longer and more intense droughts. A look at precipitation for the state as a whole indicates that since records were first kept (1883), there have been drier periods alternating with wetter periods. Starting with 1984, 20 out of 30 years have seen lower than average precipitation in California, and 2013 was by far the driest on record. This contrasts with 1978-1983, which were all above average precipitation years.
The average annual temperature statewide has increased about 2°F since 1893. (Figure 3) Over the longer term, climate paleontologists tell us that California has been repeatedly subject to droughts that “can go on for years if not decades, and there were some dry periods that lasted over a century, like during the Medieval period…The 20th Century was unusually mild here, in the sense that the droughts weren’t as severe as in the past. It was a wetter century, and a lot of our development has been based on that.” (Ingam, 2014)
Figure 4 shows that California has experienced increasing drought over the time during which records have been kept. It shows Palmer Hydrological Drought Index Levels for California from 1883 to 2013. Blue means wet, green means about average, yellow means moderate drought, and red means severe, extreme, or exceptional drought. Even a quick glance shows very few yellow and red columns on the left side of the graph, but a great many on the right side. California has experienced more drought in the last 30 years than at any time since 1883.
Unfortunately, the trend is projected to continue. Due to climate change, temperatures in California are projected to increase by 3.5-4.5°F on average by mid-century. (U.S. Global Change Research Program, 2014) Projections for precipitation are more uncertain, and may vary by region. Projections agree, however, that the snowpack will be adversely impacted. Because of the monsoonal nature of California’s precipitation, the state is dependent on the snowpack for its water. The spring snowmelt is the most important water source for recharging the state’s aquifers and reservoirs. Figure 5 shows that a 40% decline in the water content of the snowpack is projected by mid-century (top map). This would result in a > 30% decline in runoff during April-July (middle map), and a decrease of about 20% in soil moisture on June 1 (bottom map).
The combination of increased temperature and decreased snowpack is expected to result in significantly increased levels of drought in much of California compared to the late 20th Century. If these predictions are accurate, California’s problems with drought are just beginning, and will become significantly more severe over time.
The next post will explore the status of California’s current water resources.
Figure 1. Average Annual Precipitation, is from Prism Precipitation Maps, Western Regional Climate Center, http://www.wrcc.dri.edu/precip.html.
Data for California’s annual precipitation, temperature, and Palmer Hydrological Drought Index are from the Climate-At-A-Glance data portal of the National Environmental Information Center, http://www.ncdc.noaa.gov/cag/time-series/us.
Ingram, B. Lynn, quoted in Hockensmith, Steve.” “Why state’s water woes could be just beginning.” UC Berkeley News Center, 1/21/2014. http://newscenter.berkeley.edu/2014/01/21/states-water-woes.
U.S. Global Change Research Program. 2014. Climate Change Impacts in the United States: The Third U.S. National Climate Assessment. http://www.nca2014.globalchange.gov.
This post is the start of something new and different for this blog. Many people are writing about the drought in California, but I haven’t seen anything that tries to tackle the whole story: what does it mean for the future of the state?
I got interested in the question because a family member wants to move there. I have written a couple of posts on the drought in California, and having recently watched Ken Burns’s documentary on the Dust Bowl, I began to wonder: is it smart to move to California right now? Or is it like moving to Oklahoma at the start of the Dust Bowl?
(Click on graphics for larger view.)
I started looking for the answer and guess what? I couldn’t find it. I couldn’t find anything that tried to survey the whole situation, to put an estimate on just how big the California water deficit was going to be. I didn’t find anything that said whether they would be able to cover the deficit by gaining additional water and conserving the water they had.
As I researched, it became clear very quickly that nobody should die of thirst in California. Only a small portion of their water is directly consumed by people. The question quickly became: what will happen to the California economy? Procuring additional water and conserving the water they have will put significant burdens on the state. Some of them will be financial, through increased expenditures for water. Some of them will be lifestyle burdens. California is famous for a certain type of lifestyle, and millions of people have moved there to have it. Will they have to switch their lovely landscaping to desertscapes? Will they have to give up their lovely pools and golf courses? Will they have to capture used grey water and use it for other purposes? Will they have to reduce the number or length of showers they take? Will they have to stop washing their cars? Will they have to limit the number of new residential and commercial water services?
What will all this do to California? Will people brush it off like it was nothing? Or will it cause an economic recession? Will people continue to move to California, or will they begin to move out as life becomes too hard?
I couldn’t find a resource that attempted to answer these kinds of questions. And the more I looked, the more interested I got. This series of posts is the result. As I write this introduction, the series has grown to 7 parts, and I’m working on the eighth. I’m about to be away from posting for a month, but I’ve set the posts up so that they will continue to appear once weekly at the normal time. I hope you enjoy them.
Now, I want to say something about the limitations of what I’m attempting here. The data for these posts comes from a dozen or more different disciplines, none of which are my personal profession. I have tried to search out data sources that were sufficiently reliable, but there are some limitations and problems. Think of what is being attempted here as a gigantic “back-of-the-envelope” calculation. Do not regard any of the estimates as anything more than “ballpark” estimates, and the same for conclusions based on those estimates. Warren Buffet, the “Sage of Omaha,” has famously said that it is more important to be approximately right than to be precisely wrong. I have tried to follow that principle: it is more important to catch the general idea of what may happen in California than it is to know the precise cost of desalinated water from the Carlsbad plant, or the precise number of almond groves that will be abandoned.
I have had to rely on public data sources that I could access over the Internet. Much of it is high quality, but not all. I have had to combine data sources that were not meant to be combined. They may have come from different years, or used different data collection methods, or partially overlapped in what they counted. Summations and comparisons using such data are bound to be problematic, but in most cases the data didn’t contain enough information to allow me to make adjustments. Perhaps the most serious issue involves the projected future decline in the California snowpack. As I already reported in a previous blog post, the National Climate Assessment expects the California snowpack to decline by 40% by mid-century. I have understood their projection to mean that there will be a 40% decline in the amount of water from the snowpack that will become dedicated supply. But that may not be accurate, and none of the sources I looked at had the information.
So don’t buy-in to what you see in the coming posts too heavily. They are just estimates by a guy who wanted to know what to say to a family member who wanted to move to California. I couldn’t find the answer anywhere, so I constructed one myself.
I hope you enjoy the series.
If you follow this blog, you know that I have been watching the drought in California rather closely. New data is in, and it doesn’t look good.
Precipitation is seasonal in California. The winter is the wettest part of the year, the summer is bone dry in most locations. California uses reservoirs to collect water during the winter and provide it during the summer. California’s largest “reservoir” is its mountain snowpack. This accumulates during the winter, then melts gradually during the spring and summer. The runoff recharges California’s aquifers, it keeps rivers flowing, and it is collected into man-made reservoirs.
Because it is so important, California measures its mountain snowpack. Because snow can be light and fluffy or heavy and wet, the measurement they use is the water equivalent in inches. Think of it as the depth of water that would result if you melted the snow. A bucket may have 10 inches of snow in it, but if you melt it, the water would only be a 1-4 inches deep.
The water content of the snowpack generally peeks in early April, thus the April measurements are the most important. The California Snowpack Survey for April 1, 2015, found that the snowpack held the equivalent of only 1.4” of water, when the historical average is 28.3”. At one of the measuring sites, for the first time ever, there was no snow at all, the ground was bare (Phillips). (See photos at right.) The bottom line is that California’s most important reservoir is holding about 5% of the water it usually holds.
(Click photos for larger view.)
There are two basic reasons for the lack of snowpack. First, less precipitation is falling. Data from March 2015, has not been posted, but the chart at right shows December – February precipitation in California for the past 10 years. Precipitation has been significantly below average for each of the last 4 years. I suspect that when March data is posted, 2015 will look much worse than it does in this chart.
The second reason is that temperatures have risen. The second chart at right shows the data. Warmer temperatures, especially over the last 2 years, mean that precipitation that would have fallen as snow instead fell as rain. And some of the snow that did fall melted right away.
This is the 4th year of severe drought in California. The state has just put in place the first mandatory water conservation requirements in its history. The following links will take you to a series of articles that the New York Times has been running on the new requirements, and on how the state is coping with the drought.
For the California Snowpack Survey press release: California Department of Water Resources. Sierra Nevada Snowpack Is Virtually Gone; Water Content Now is Only 5 Percent of Historical Average. http://www.water.ca.gov/news/newsreleases/2015/040115snowsurvey.pdf.
The press release contains a link to photos of the Phillips snowpack survey site. If the link doesn’t work, here is the url: https://d3.water.ca.gov/owncloud/public.php?service=files&t=e5a72c13a0d5f1b4f8b49e584a0d8da7.
The precipitation and temperature data for California were obtained using the National Oceanographic and Atmospheric Administration’s Climate At A Glance Data Portal, http://www.ncdc.noaa.gov/cag/time-series/us.
In the previous two posts, I reported that almost half of all water consumed in the United States is used for power generation. Irrigation is the second largest use. The population of a state and its land area account for about 74% of the variance in water consumption between states. The states with the largest “excess” water consumption compared to their population and size were Idaho, Nebraska, and Montana.
As you look at the following charts, keep in mind that the USGS may not have estimated all sources of water withdrawal identically across all years. Some of the differences may be due to gaps and changes in the way the data was gathered, and I don’t know which data might be affected.
The first chart at right shows that for the United States as a whole, water consumption seems to be increasing slowly, from 395,801 million gallons per day in 1985 to 407,273 million gallons per day in 2005, an increase of about 3%.
The second chart at right shows water consumption by state for 1985, 1990, 1995, 2000, and 2005. The chart is a bit hard to read because the columns are so small. Click on it to enlarge it on your screen to get a better view.
For some states, consumption doesn’t seem to change much, for instance, Kentucky. For other states, water consumption seems to jump around inconsistently, for instance, California, Colorado, and Kansas. In some states, water consumption seems to be consistently declining, for instance Delaware, Massachusetts, and Nevada. In other states, it seems to be consistently increasing, for instance Arkansas, Florida, and Missouri.
The following sources were used to create the charts. They are all available on the United States Geological Service website at Water Use in the United States, http://water.usgs.gov/watuse.
- Estimated Use of Water in the United States in 2005.
- Download 2000 Data For Counties.
- Download 1995 Data for Counties and Watersheds.
- Download 1990 or 1985 Data for Counties and Watersheds.
In my previous post I reported that the United States consumed about 410 billion gallons of water per day, and that almost half of it was used to generate electricity. The first graph at right shows 2005 water consumption by state and by use.
First, the largest users are California, Texas, Idaho, and Florida. Between them, these 4 states use more than 26% of all water consumed in the United States.
Second, the amount used varies tremendously between states: California uses 112 times as much as does Rhode Island.
Third, in most states, the major use is power generation. However, in some states, such as California, Idaho, Montana, and Nebraska, it is for irrigation.
Because the amount of power used in a state is a function of population, and because the amount of irrigation is a function of the land area of the state, it would stand to reason that the population and land area of a state must account for much of the variance between states. It does. In fact, it accounts for about 74% of the variance (r-squared = 0.74).
The second graph at right shows per capita water consumption by state. Idaho, Montana, Wyoming, and Nebraska have much higher per capita water consumption than the others. These are states with lots of irrigation but relatively small populations. Missouri ranks 18th highest in per capita water consumption.
The third graph at right shows water consumption per square mile of land area. New Jersey, Maryland, and Connecticut have much higher consumption per square mile than do the other states. They are small states with dense populations. Missouri ranks 30th highest in gallons consumed per square mile.
One can use linear regression to predict what each state’s water consumption “should be” given its population and land area. The regression accounts for about 74% of the variance between states. That’s pretty good. The fourth chart at right shows how much each state’s actual consumption differed from its predicted consumption, as a percentage of predicted consumption. Using this method, water consumption in Idaho, Nebraska, and Montana exceeded predicted consumption the most. Idaho’s consumption was 5.5 times as much as predicted.
For water consumption: Estimated Use of Water in the United States in 2005, Circular 1344, U.S. Geological Survey, http://pubs.usgs.gov/circ/1344.
For population: Table 1. Intercensal Estimates of the Resident Population for the United States, Regions, States, and Puerto Rico: April 1, 2000 to July 1, 2010, (ST-EST00INT-01), U.S. Census Bureau, Population, http://www.census.gov/popest/data/intercensal/national/nat2010.html.
For land area of the states: Profile of the People and Land of the United States, National Atlas, http://nationalatlas.gov/articles/mapping/a_general.html#one.
For statistics: a linear regression was performed using state water withdrawals as the dependent variable with state population and state land area as the independent variables. The regression was performed using StatPlusMac using the default settings.