The Colorado River is in a state of crisis — which means the seven states and Mexico that rely on its water are in trouble, as well. Last summer, a lack of precipitation and meager snowpacks in the Rocky Mountains led to a Tier II shortage being declared for the river: The water level at Lake Mead, America’s largest reservoir, had dropped to 1,042 feet, or just 28 percent full.
After 20 dry years, Lake Powell was also at the lowest level it had ever been (just 24 percent full) with an elevation of 3,523 feet, just below its buffer elevation of 3,525 feet. And while 4.1 million acre-feet of water are predicted to arrive this spring and summer, users of that water need 7 million acre-feet, resulting in a deficit.
The potential consequences include not only water shortages, but also a reduction in renewable energy. If the water level drops any lower, the Grand Canyon Dam’s electric generating plant may not be able to generate power. Not only that, but downstream at Lake Mead, the drop in water level has already reduced the electric power available from the dam’s turbogenerators to 1,362 megawatts, a reduction of 36 percent from its design output. Should the water level drop to 1,000 feet, Hoover Dam will stop generating electricity (“dead pool”), and fossil-fired generating plants will have to replace it.
The Southern Nevada Water Authority (SNWA) has recently switched on the Low Lake Level Pump for the first time. The Tier II shortage means that the federal government could demand cuts. Arizona, Nevada and Mexico will surely see reductions to their water supplies. (Arizona alone stands to lose 21 percent of its allotment, or 592,000 acre-feet; meanwhile, the state’s population is at 7.2 million residents and growing.) All in all, the prospect of severe water rationing is looming.
The federal government has directed the river compact states to cut their water use; the states had until the end of January to come to a consensus and submit a proposal. As of this writing, six states have created a plan; California declined to join them.
The first line of defense against drought, then, and the most conservative one, is water conservation.
Southern California’s Metropolitan Water District has told residents to reduce watering of their yards and lawns to once a week beginning in June. The district pulls water from the Colorado River and the California State Water Project. The East Bay Municipal Utility District has instituted a 10 percent reduction in water use. It serves 1.4 million customers in Contra Costa and Alameda counties.
In 2014, California passed the California Sustainable Groundwater Management Act. More than 500 water management entities had to submit plans to the state detailing how they would manage groundwater. The goal was to reduce the pumping of groundwater, to help maintain its quality — and to not to run out of it.
The Truckee Meadows Water Authority (TMWA) and Southern Nevada Water Authority (SNWA) advocate for such measures as the reuse of wastewater from industry for irrigation and xeriscaping. TMWA has told the Northern Nevada public that water conservation, recycling and xeriscaping, as well as water directed into reservoirs, will be sufficient to supply us for the next two decades despite an increase in population. As for SNWA, it has long term plans to reduce each resident’s use of water to less than 100 gallons per day.
One conservation measure is the direct recycling of wastewater into drinking water by purifying the output from wastewater treatment plants. Direct Potable Reuse (DPR), also known colloquially as “toilet to tap,” is legal in Texas, and Arizona allows it on a case by case basis. Science supports adopting this method, but political acceptance requires getting the public to focus on the safety of the water coming from the tap more than whence it comes.
Unfortunately, the consensus of climate scientists is that rain will predominate in place of snow in the coming decades, and given that snowpacks themselves constitute a major reservoir, this new pattern will exacerbate water shortages even as our population increases and our need to grow food and use water to extract minerals increase. (This leads one to the conclusion that TMWA’s projections are probably too rosy for comfort.)
We are facing a brutal reality. No matter how much we try to conserve, our growing population requires more fresh water while climate change is reducing the supply.
If conservation alone can’t help us, there is another solution that, in combination with conservation, can make a difference: The construction of large-scale desalination plants along the Pacific coast are inevitable if we are to avert disaster.
There are already 14 small-scale desalination plants on the west coast, but their production is far too little to make a meaningful contribution to potable water supply. The largest one is Poseidon’s Carlsbad plant, which produces 56,000 acre-feet of potable water per year, enough to supply about 10 percent of San Diego’s needs.
Many countries get drinking water from seawater this way. The Israelis get 80 percent of their potable water needs from desalination plants, and Saudi Arabia has desalinated seawater for many years. U.S. Navy ships and submarines supply sailors with water for drinking and bathing from “stills” installed on-board.
There are two ways to utilize desalination to help Nevada, and they are not mutually exclusive. The first is for our state government to help finance the construction of desalination plants in California and Mexico. In return for Nevada’s investment, both California and Mexico would surrender Colorado River water rights to Nevada.
The second way is for Nevada to co-finance desalination plants and pipelines that would bring potable water here. This option is far more expensive but offers the advantage of a more reliable supply, as our own population growth, along with increasing agricultural and mining demand, may well outstrip the Colorado River’s capacity, while climate change reduces the snowpack — and therefore, the water available from the Truckee River.
It is important to recognize that desalination is not entirely benign. A desalination plant requires large amounts of electricity to make potable water, and if fossil-powered generators make that electricity, they will contribute to pollution and climate change. If a desalination plant utilizes reverse osmosis, then the plant will make a gallon of potable water from two gallons of seawater, and must dispose of a gallon of concentrated brine. Simply discharging the brine into the ocean without careful planning can harm marine life, and the intake pipe’s screens can kill fish. Hence, desalination projects must show a favorable cost/benefit ratio: In return for a risk that is acceptable, potable water is produced that can save lives.
There is also a political problem: Coastal residents living near a proposed site for a desalination facility may fiercely oppose it, accepting gross exaggerations of the risks as gospel — especially if the plant, either directly or indirectly, serves what they perceive to be an urgent need in another state or even another neighborhood with which said coastal residents do not identify. An example of this latter objection would be an affluent and largely white community being reluctant to host a desalination plant in order to assist minority communities further inland.
If, on the other hand, the desalination is of the thermal type, which boils seawater and captures the condensate, brine is not a problem — but disposal of the salts left behind becomes an issue. However, these are a source of commercially useful chemicals, the sale of which can help pay to operate the plant. Thermal plants that utilize mirrors to focus sunlight to boil the water have been successfully demonstrated. (A new reverse osmosis desalination plant can be designed to make its own sodium hydroxide, which is used to pretreat seawater entering the plant. Enough sodium hydroxide can be made to not only serve a plant’s needs, but also to sell to other users. A new plant can also make hydrochloric acid for various industrial uses.
Currently, at least in our region, desalinated water is more expensive than river water. The water from the Carlsbad desalination plant supplying San Diego, representing 10 percent of potable water supplies as of 2019, costs $2,200 per acre-foot in 2018, whereas water from the Colorado River costs $1,200 per acre-foot. (It is important to note, however, that desalination costs have seen a significant drop compared with a decade ago.)
There is yet another option available locally in Nevada. Brackish water sources exist in Nevada, according to the U.S. Geologic Survey. Seawater has roughly 35 grams of dissolved solids per liter of water; brackish groundwater generally has between one and 10 grams of dissolved solids per liter. Brackish water is unsuitable for drinking, but it requires less energy to desalinate than seawater and produces less brine requiring disposal. Hence, it is likely to be feasible to desalinate brackish groundwater in Nevada to supply potable water at lower expense than to pay California or Mexico to desalinate seawater. A variant of this approach would be to use brackish water for industrial and agricultural uses (cooling, irrigation, livestock watering), reserving potable water for drinking.
As there are environmental consequences to all options, it would be prudent to examine combinations of investments in all three, picking a mix that offers the best package of reliable, safe potable water at a reasonable cost and with manageable environmental impacts.
It is vitally important to remember that desalination is not a magical cure for drought and should not replace water conservation measures. Rather, it is an effective way to close the gap between what the efficient use of river and groundwater produce, and what we need.
Dr. Ron Aryel, a resident of Reno, is a pediatrician who also founded a real estate investment business in 2014 which owns both apartment buildings and single-family homes. He ran an award-winning pediatric practice for 11 years and served on the City of Reno’s COVID Task Force. He and his wife Stacey, a retired pediatric neurologist, run the Albee Aryel Foundation, which supports students from disadvantaged backgrounds through university education.
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