generate additional
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to generate environ-
mental benefits.
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he case studies in this report support water policy conclusions that are widely applicable in the western United States. Overall, our analysis indicates that energy implications of water policy decisions are large and warrant inclusion in water and energy policy decisions. All three case studies demonstrate that inclusion of energy considerations can improve resource management decisions and avoid potentially significant unintended energy consequences.ENERGY IN URBAN WATER USE
The most striking conclusion is that the amount of energy required for end uses of water is the largest component of energy use in the urban water supply cycle. Therefore, urban conservation, particularly for energy intensive uses such as clothes washers and commercial cooling towers, is important regardless of the source of the water or location of its use. San Francisco, as well as Los Angeles, should be aggressively pursuing water conservation.
This finding implies that policy actions that affect water use may have much larger energy implications than policy actions that affect the mix of physical water sources. This is true in San Diego, at the most energy intensive “ends” of the State Water Project and Colorado River Aqueduct, but it is even more valid in other locales.
However, our analysis also reiterates that conveying water can be highly energy intensive. Since conservation saves all of the “upstream” energy inputs as well as end use inputs, conservation in areas with energy intensive water supplies will save substantially more energy than conservation in other areas.
Another conclusion from the urban case study—as well as the agricultural analysis—is that water reuse is far less energy intensive than any physical source of water other than local surface water. The San Diego case study explicitly supports this point, and tailwater recovery uses far less energy than urban water recycling since it usually requires no more than lifting tailwater from low points to high points on each farm. Even groundwater pumping is more energy intensive in San Diego and the Westlands Water District than water recycling from urban wastewater; and the depth to groundwater in these locations is not atypical for western settings.
ENERGY
DOWN
THE DRAIN
The Hidden Costs
of California’s
Water Supply
August 2004
ENERGY IN AGRICULTURAL WATER USE
In agricultural settings, energy use varies widely and it is not possible to generalize about which stage of water use dominates. Source and conveyance and end use of water appear to demand the largest portions of energy in water use, but their respective energy use will vary by water source, district location, topography, and irrigation technology, among other factors.
The energy impacts of agricultural water policy decisions may also extend beyond the energy embedded in water use. For example, in some cases, water policy decisions may affect the amount of energy used for harvest and cultivation, which can be quite large. The Westlands Water District case study shows that the energy implications of land fallowing are complicated and worthy of further study, not just in Westlands but in other settings where fallowing (permanent, dry-year, or rotational) is being considered.
Our analysis indicates that the energy impacts of fallowing farmland depend largely on where the water formerly used to irrigate that land is sent instead. From an energy perspective, a combination of conservation and water recycling may be the best path for meeting growing urban needs, while water freed up in agriculture due to efficiency im- provements and fallowing might be the best source to satisfy environmental flow needs.
Finally, the Columbia case study demonstrates that foregone hydroelectric pro- duction (energy opportunity cost) can be very significant when irrigation water is diverted above power production facilities. For example, the foregone energy production in the Columbia Basin Project is the equivalent of 25 percent of the total energy use for the city of Seattle. In some cases, particularly during times of high energy prices, it may be possible to purchase water from farmers for environmental flows and finance those purchases through the additional hydropower revenues. Our analysis strongly suggests that environmental flows and quality can be enhanced in the Columbia Basin without permanent land retirement or reduction in power production, at least in some dry years.
IMPLICATIONS OF THE CASE STUDIES
The analysis in this report supports two primary recommendations:
Decision makers should better integrate energy issues into water policy decision making.
The background information in Chapters 1 and 2 and the case studies in Chapters 3, 4, and 5 demonstrate that looking at energy use and water use simultaneously gener- ates valuable insights that do not arise from separate policy analyses of water and energy issues. The specific policy and planning recommendations that flow from this primary recommendation are presented below. Many of these recommendations are potentially relevant—with appropriate modification to account for differences in the policy context—outside California and the Columbia Basin.
Water conservation should be given higher priority by policy planners in both water and energy sectors.Although many planners in the water sector support conservation,