How can water supplies be increased

Box discusses the Animas-La Plata project in south-western Colorado, which is an example of the complexities that surround contemporary dam authorization, appropriation, and construction.

In efforts to augment water supplies, some basin states and. Congress authorized the Animas-La Plata project in , calling for a multipurpose dam project to serve a range of agricultural, municipal, and industrial uses in southwestern Colorado.

Although scheduled for construction in the early s, discussions were initiated to achieve a negotiated settlement of water rights claims of the Southern Ute Indian and Mountain Ute tribes in southwestern Colorado.

Following negotiations, a settlement of water rights claims held by these tribes was agreed to in a Final Settlement Agreement, signed on December 10, In , the U. Fish and Wildlife Service issued a draft biological opinion regarding the federally endangered Colorado pike minnow and how it might be affected by Animas-La Plata.

A final biological opinion was issued in , which allowed for construction of several Animas-La Plata project features, but limited annual project depletions to 57, acre-feet while an endangered fish recovery program was conducted.

After the U. Reclamation worked with the Fish and Wildlife Service to address new biological information, and in the Service issued a biological opinion with a reasonable and prudent alternative limiting project construction to features that would initially result in an average annual water depletion of 57, acre-feet.

Construction of the Ridges Basin Dam, the centerpiece of the Animas-La Plata Project that will impound , acre-feet, began in The reservoir, to be named for former Colorado Senator Ben Nighthorse Campbell, is expected to be filled in The history of the Animas La-Plata project reflects how difficult it can be for western water projects to move from planning to construction.

The process today is far more complicated than during the s and s. Although future storage dams may be built within the Colorado River basin, the Animas-La Plata experience offers little evidence that they will be built quickly. Although a diversion dam on the Virgin River has been discussed, there is no current proposal to build such a project, and it is one of the few dam projects that has even been discussed in the basin in recent years.

An interesting chapter in the history of efforts to augment Colorado River basin water supply storage involves various plans to import water from outside the basin. Parsons Company of Pasadena, California. The plan envisioned moving large quantities of water from water-rich regions of Alaska and the Canadian Yukon to the arid western United States through a complex system of reservoirs, tunnels, pumping stations, and canals.

Dams were also to generate hydropower, sales of which were to help finance project construction. Political and environmental objections would also impede, and likely block, attempts to revive even a scaled-down version of the NAWAPA scheme. Similarly, prospects of towing icebergs south from Alaska or other arctic regions to augment Colorado River water supplies are equally unrealistic.

The following sections of this chapter examine some nonstructural and nontraditional means of augmenting water supplies. Weather modification, including cloud seeding to increase rainfall and suppress hail, has long generated interest among scientists, public officials, and private practitioners in a dozen or more nations.

Over this period, research investment by agencies of the federal government has waxed and waned. Early experiments conducted by the U. Weather Bureau in the late s showed sufficient promise that federally sponsored efforts were scaled up in the s with programs overseen by the Weather Bureau, the U. Air Force, and the National Science Foundation, all of which supported cloud seeding research into the s and s.

The mids marked a high point of federal support for cloud seeding, and the National Weather Modification Act of spurred federal research efforts and mandated a Department of Commerce Weather Modification Advisory Committee to coordinate research among federal agencies.

In this same time frame, assessments were made of scientific progress made over the preceding decade and a half. The assessments include a series of reports from both the National Research Council NRC and the National Science Board that concluded that experimental evidence for cloud seeding had not yet definitively established its scientific efficacy NRC, , , ; NSB, The National Research Council subsequently in issued a report on the prospects of cloud seeding and other weather modification techniques, concluding that:.

There is still no convincing scientific proof of the efficacy of intentional weather modification efforts. In some instances there are strong indications of induced changes, but this evidence has not been subjected to tests of significance and reproducibility. This does not challenge the scientific basis of weather modification concepts. Rather, it is the absence of adequate understanding of critical atmospheric processes that, in turn, lead to a failure in producing predictable, detectable and verifiable results NRC, Since the NRC and WMA reports were issued, some scientists have sought common ground with operators to develop a cloud seeding program that would include scientifically controlled watershed experiments Garstang et al.

Federal support for cloud seeding research has generally declined since the mids. Nevertheless, several parties and states in the Colorado River basin maintain a strong interest in the prospects of cloud seeding to increase precipitation. In light of the stress on federal funding for discretionary expenditures, a renewed large-scale, federally led weather modification initiative does not appear likely AAAS, For the foreseeable future, weather modification experiments and operations will depend mainly on funding from state governments, local communities, and private-sector entities e.

Six of the seven Colorado River basin states presently support some type of precipitation or snowpack augmentation operations WMA, The most prominent cloud seeding project in the basin may be one sponsored by the Wyoming Water Development Commission.

The program is important because of its potential scientific and operational evaluation for the Colorado River basin states and because the 5-year program is to utilize a solid scientific base for the experiments. If the Wyoming pilot trials increase snowpack by 10 percent, the additional yield would, on average, be on the order of , to , acre-feet of additional runoff each spring WWDC, , which would represent a notable increase in water supplies. In addition to the Colorado River basin states, entities such as municipalities and the ski industry are interested in the prospects of augmenting water supplies and snowpacks by cloud seeding.

Denver Water, for example, commenced cloud seeding again in after 20 years of putting its program on hold. In evaluating the success or benefits of cloud seeding operations, the experience of six decades of experiments and applications that failed to produce clear evidence that cloud seeding can reliably en-.

Of course, clear evidence is difficult to produce in cloud seeding experiments, as they are not amenable to case-control studies. Furthermore, such experiments are seen by many as being relatively inexpensive even if they do not definitively result in greater precipitation. Given increasing demands for water across the Colorado River basin, cloud seeding is likely to continue to be pursued as a means for augmenting water supply.

Scientists and engineers, governments, and advocacy groups have long investigated desalination as a means of augmenting freshwater supplies. Most attention has been directed to converting seawater to potable freshwater, while less attention has focused on subterranean and surface brackish water desalination. There have been steady scientific and engineering advances in the technologies of salt water conversion, and several desalination facilities have been constructed.

Advances in technology have led to cost reductions, improved efficiency, and an increase in the numbers of desalination plants worldwide. In addition to interests of municipalities and utilities for coastal desalination facilities, energy companies are operating small desalination plants on offshore oil and gas exploration and production rigs; there are nine rigs with desalination facilities off the coast of California California Coastal Commission and State Lands Commission, Not all desalination initiatives have proven fully successful, however.

For example, in water authorities jointly sponsored a privately financed desalination plant at Tampa Bay, Flor-. As of May , the plant was not in operation, being plagued by management and technical problems Cooley et al. The experience of the City of Santa Barbara, California represents another prominent example of the challenges associated with large-scale desalination see Box Recent improvements in desalination technology have led to energy cost reductions per unit of water produced.

There is, for example, a variety of membrane technologies such as reverse osmosis, nanofiltration, and ultrafiltration. These all remove salts, dissolved organics, bacteria, and other seawater constituents from salt water Pankratz and Tonner, There is also a range of thermal technologies that boil or freeze water, then capture the purified water while the contaminants remain behind.

Energy requirements and costs are important considerations in desalination projects and greatly affect construction plans and decisions in the United States especially as compared to areas such as the Middle East, where oil and natural gas costs are heavily subsidized. Energy costs notwithstanding, relative production costs have fallen since the early s and the capacity of facilities has risen AMTA, In the United States there is some interest in coupling future desalination plants with new power plant production for cogeneration to reduce energy cost in desalination; rising energy costs, however, make it unclear if this trend will continue Cooley et al.

On the other hand, technical advances may continue and increase desalination efficiency even if energy costs rise. For example, a team led by scientists from the Lawrence Livermore National Laboratory estimates that a membrane system using carbon nanotubebased membranes may be able to reduce future costs of desalination by 75 percent compared to current reverse osmosis membrane technology Holt et al. Longstanding federal research and development programs for desalination have been advanced by a series of congressional authorizations, such as the Water Purification and Desalination Act of P.

State governments and municipal water districts are also investing in desalination research, development, and demonstration facilities. The Bureau. The City of Santa Barbara, California, relies heavily on rainfall and local groundwater to meet its water supply needs. These sources were impacted by severe drought conditions between and , which caused sharp declines in local reservoir levels. Construction of a reverse osmosis facility began in and was completed in The plant successfully produced water during its testing phases, but soon after plant completion, drought conditions in the region subsided.

The plant was placed on active standby mode because of the high costs of producing water during nondrought periods. At the same time, the higher costs of water driven by the desalination plant and the connection to the State Water Project contributed to declining water demands. Our team of policy experts, scientists, economists, and attorneys has a year history of working where decisions are made, sweating the details, creating evidence-based solutions and holding decision makers accountable.

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