There was a time when engineers and managers attending a water industry conference could tell where they were in the country solely by the opening remarks. East of the Rockies, speakers acknowledged a need to plan and to make investments in the future water supply, but were disheartened by public apathy. In the West, most presenters quoted a line attributed to Mark
Twain: Whiskey is for drinking, and water is for fighting over.” While easterners either took water for granted or nervously channeled the surplus away from their towns, westerners thought of water supplies as limited, even scarce.
Today, the distinctions have faded, and a national convergence is taking place in the water industry. In an odd twist, a recent water allocation agreement between Imperial Valley agriculture and the city of San Diego comes at the same time states, including Georgia, Florida, Alabama, Virginia, and Maryland, are contesting water rights. The old divides between western and eastern water management have morphed into an acceptance that water is a precious resource nationally and globally. The most popular saying now at conferences is, Water is the oil of the 21st century.”
How will the water supply be managed in this new arena? The solutions to today’s water issues lie in administration, allocation, and conservation.An age-old question
Is water a commodity or a public resource? It falls from the sky, free of charge. Yet people pay for water to cover the cost of treatment and distribution. So, at first glance, water would appear to be a commodity because it is bought and sold.
In a January 2004 letter to the L.A. Times, California environmental activist Dorothy Green stated that, in California, the water is owned by the people. She condemns a future vision in which an important life necessity becomes profit driven.” Many easterners would be surprised to hear this opinion coming from the West, which in the past viewed water as a property right. But a 1983 California Supreme Court decision on water diversion from Mono Lake by the Los Angeles
Department of Water and Power defined the relationship between the state’s water-rights system and its public trust doctrine, which protects environmental and recreational values of tidelands and navigable lakes. The court’s ruling protected Mono Lake for the benefit and use of the public.
The future likely will see water systems placed in the public interest with many previous rights and guarantees nullified, and a system administrator mandating operations. Access to the water system will be weighed against public interest. In keeping with this trend, more states are shifting from treating water as a property right to finding administrative or regulatory solutions for water allocation issues.
It is unlikely that the courts will challenge this new model. Water issues are so complicated and have so many variables that courts cannot fashion Solomon-like decisions. Their only practical option is to establish a custodian. This was the approach applied to the Arizona-vs.-California water debate, with the appointment of the Secretary of the Interior as a water master. For the current water disagreement between Georgia, Florida, and Alabama, the courts could turn again to a third-party administrator. The courts simply are not prepared to deal long term with the changing complexities of water issues.The allocation equation
Some say the world has the same amount of water it did 500 years ago. While that figure may be open to debate, another statistic is widely accepted: Since meteorological records have been kept, a water shortage (any period with less than average rainfall) occurs seven out of 20 years, which is almost once in a three-year period. This frequency holds true for most parts of the country. Of course, no one can predict drought years. And few, if any, water systems are designed to handle three consecutive dry years without user restrictions.
Almost everywhere in the country, between 70 percent and 80 percent of the water supply goes to agriculture, while 20 percent to 30 percent supports urban interests. If there was an efficient way to change the ratio slightly during a water shortage, with agriculture receiving, for example, between 65 percent and 75 percent of the water supply, a region could see its way past the worst conditions of a low-water period.
Water rights are no longer an issue just in the West. The old divides between western and eastern water management have morphed into an acceptance that water is a precious resource nationally and globally.
The water supply industry must find a way to shift water supplies more efficiently, even if temporarily, to meet these goals. The answer may lie in creating water supply option programs. While there is enormous controversy around the country about using market incentives to create efficiency, this technique has proven much more effective than the alternative administrative/ regulatory/central planning approach.
First, it is unrealistic to expect regulators to anticipate meteorological conditions 20 or 30 years in the future. Additionally, using urban dollars to encourage agriculture conservation is an effective conservation tool, as shown in practice in Southern California. The most vocal criticism of such methods usually comes from the growth management community that seeks to make water the sole growth-limiting factor.
Urban interests can play a part by investing in practical water storage solutions. In the past, the devastation of floods inspired communities to build flood control systems, channeling water away from development. While this idea was certainly sensible, it didn’t take into account water storage for future use. The water industry now is looking at ways to hold onto rainwater for longer periods of time before losing it to tides and oceans. In essence, this is the plan for south Florida and the Everglades, as well as for California’s Bay-Delta ecosystem.Emerging technologies and attitudes
Aquifer storage and recovery (ASR) is one solution that balances a region’s dry, average, and wet years. ASR technology has grown from an obscure water conference” topic to a common tool. The technology behind ASR – storing water underground, then bringing it to the surface when needed – has been proven and, depending upon scale, is more cost-effective than building above-ground reservoirs in many cases.
Desalination is another technology with the capability to enhance supplies, most likely for municipal/industrial interests. For agriculture to remain viable, it must be supplied with lower-cost water. Desalination can provide ultra-pure water, at a higher cost, to meet manufacturing and possibly urban demands. The technology has become competitively priced for treatment of brackish water. Treatment of ocean water is on the horizon as a viable component of major urban water supply systems, both in the West and the East (see Reverse Osmosis).
Finally, there is a silent partner that must be considered in water supply allocations – the natural environment. The lesson learned in both the Florida Everglades and California’s Bay-Delta is that the environment needs a portion of the fresh water supply if it is to be sustained. Urban water interests around the country have the opportunity to seize the high ground in the inevitable fight looming over future water allocations.
Natural environments, such as the Florida Everglades, must be considered in water supply allocations. These areas need a portion of the fresh water supply if they are to be sustained.
Everyone wants a healthy environment and economy, and the urban water interests are better positioned to create the collaborative network and alliances necessary for that outcome.
Developing such relationships will prove to be the skill set most in demand to solve our water problems in the future.Conservation and appreciation
In Third World countries, either the cost of water is high compared with typical incomes or the time and effort necessary to fetch water from the local stream, well, or water pump is significant. Conservation is a necessity rather than a philosophy.
In the United States, however, where the average water bill is less than $20 per month, water conservation can be a hard sell. People in some regions might assume the lush plants and grasses along highways and in parks are indigenous. The irrigation required to transform sub-tropical South Florida into a true tropical paradise, however, can lead to daily water use of more than 500 gallons per person, compared with the nationwide average of 80 to 100 gallons per person per day. In its natural state, the non-irrigated grass on the Florida turnpike turns as brown in winter as California’s golden hills turn in summer.
Attitudes about water use must change. Across-the-board conservation will be a key component of water supply management policies in the future.Water in the 21st century
The age-old questions are still being asked: Is water a public resource or a commodity? Is water free? What happens if someone unfairly profits from its use?
The fact is that everyone pays for water. Once that is understood, many of our water problems can be a thing of the past. At the same time, water is a public resource. Management of this precious resource must use all of the creative tools available, including economic incentives. The changes are only beginning. The time is here to move toward thoughtful allocation, creative storage options, sensitive water supply management, and conservation.
Water conservation can be a hard sell in the United States, where the average water bill is less than $20 per month. Nevertheless, conservation will be a key component of water supply management policies in the future.
John Woody” Wodraska is the national director of water resources for PBS&J in West Palm Beach, Fla. During his 30 years in the industry, he has worked with sensitive water management issues on both coasts of the U.S. as executive director of the South Florida Water Management District and as general manager and CEO of the Metropolitan Water District of Southern California. Wodraska can be reached at 561-689-7275; e-mail: email@example.com.
Where all the water goes
Water use in the United States was an estimated 408 billion gallons per day in 2000, according to the U.S. Geological Survey (USGS). This total has varied less than 3 percent since 1985 because withdrawals have stabilized for the two largest uses – thermoelectric power and irrigation.
The USGS provides the following breakdown of water withdrawal – surface and ground water – for 2000:
- 48 percent for thermoelectric power;
- 34 percent for irrigation;
- 11 percent for public supply;
- 5 percent for self-supplied industrial; and
- 2 percent for self-supplied domestic, livestock, aquaculture, and mining.
During 2000, about 85 percent of the U.S. population obtained drinking water from public suppliers, compared to 62 percent in 1950. Surface water provided 63 percent of the public-supplied drinking water in 2000, according to the USGS. More facts about water use, including data by county and watershed, are available at http://water.usgs.gov/watuse. For information about the nation’s water quality, see http://water.usgs.gov/nawqa; and for current streamflow and ground water records, see http://water.usgs.gov/waterwatch.
Reverse Osmosis Processes Prove Promising for Seawater Desalination in the United States
Is the ocean the next major source of drinking water supply for the United States? The answer most likely is yes. Making drinking water from seawater has been ongoing for more than 40 years. Ocean-going ships, as well as many desalination plants in the Mediterranean, Caribbean, and other parts of the world, have been making drinking water from seawater for many years.
Continuing advances in desalination technology, combined with a growing need for new freshwater supplies, is prompting many municipal water utilities in the United States to consider ocean desalination.
Generally, seawater desalination is achieved by one of two processes: thermal or membrane. Thermal processes use heat and pressure changes to condense fresh water from evaporated seawater. These processes are well-proven and widely used, though unlikely to be found in the United States for large-scale desalination plants. Membrane processes using reverse osmosis
(RO) are the emerging technologies of choice.
Producing drinking water in an RO membrane process requires membrane elements and seawater pumped at high pressure. The high-pressure seawater is applied to the membrane elements, which block nearly all dissolved salts, minerals, and ions in the seawater and allow freshwater to pass.
Osmosis, a natural process that occurs in plants and animals, is the movement of a fluid through a semi-permeable membrane into a solution of higher concentration. Osmosis tends to equalize the concentration of fluids on each of the membranes. The greater the difference in concentration of the fluids across the membrane, the greater the osmotic pressure. Reverse osmosis uses pressure to overcome osmotic pressure and change the flow of fluid from the higher concentration solute to the lower concentration side. The pressure needed for seawater reverse osmosis (SWRO) is 900 to 1,000 psi.
Energy consumption and membrane life are two important aspects of SWRO plants. Considerable energy is required to pump seawater to high pressure. Efficiency of the high-pressure RO pumping system must be closely evaluated during design because even small efficiency losses can result in significant increases in water production costs.
Membrane elements are one of the most costly items of a SWRO plant. Large SWRO plants have thousands of membrane elements, with each element designed for a fiveto seven-year lifetime at a cost of about $500. Damage to the membranes caused by poor operation or poor seawater pretreatment can result in high operating costs for cleaning, high-energy consumption, or premature replacement.
Pretreatment of seawater before the RO process is important. Particulate and organic material in seawater can cause serious damage to the membranes or create long-term operational problems. Particulate can clog membranes and organic matter can cause bio-growth in membranes, resulting in frequent cleaning or irreversible clogging. The pretreatment system must consistently produce water with low turbidity and silt density index (SDI). SDI is a qualitative analysis used in membrane plant design to measure particulate that is well below the range of turbidity readings and particle counters. An SDI of 3 to 5 is recommended for optimum membrane performance. Seawater quality can change significantly throughout the year, however, so proper design of a SWRO plant must evaluate performance of the pretreatment system through the full range of seawater conditions.Concentrate disposal is another important issue with SWRO plants, which produce about 1 gallon of concentrate for every gallon of fresh water produced. The concentrate has approximately twice the total dissolved solids (TDS) concentration of the source seawater. For example, if the intake seawater is 35,000 mg/l TDS, the concentrate will be approximately 70,000 mg/l. Negative environmental impact is a critical problem and discharge of the concentrate back into the ocean must be evaluated closely as part of the plant design. Hydrodynamic modeling, combined with biological studies, is needed to predict the effects of the concentrate discharge and to meet permitting requirements for the project.