Fluid Situation: What does the future hold for Tucson’s water supply? Only one thing is certain: It’s all going to cost more.
By Dave Devine and Molly McKasson, published by the Tucson Weekly, March 6, 2008
The Tucson City Council may soon be forced to answer some difficult questions about the quality of water that Tucsonans will have to live with.
The stakes are high: Either we’ll see a substantial decrease in our water quality, or a considerable hike in our water rates.
At the same time, a growing number of scientists and policymakers are warning that communities, like Tucson, that rely heavily on the Colorado River for water may not even be asking the right questions. With global-warming concerns on the rise, reports indicate that the river could have much lower flows in the future.
“We have built an unsustainable civilization in the Southwest,” says Tim P. Barnett, a physicist at the Scripps Institution of Oceanography in San Diego. Barnett is also co-author of an article soon to appear in the journal Water Resources Research titled, “When Will Lake Mead Go Dry?”
Barnett believes cities like Tucson need to ask tough questions now–or risk potentially devastating consequences in the not-so-distant future.
“Currently, the outflow of the Colorado is greater than the inflow,” Barnett comments in an interview. “Apparently, no one has ever looked at the way people keep the books on this river. There has been deliberate overdrafting, while minimizing climate change and infiltration and ignoring increased evaporation due to drought.”
In the coming weeks, a more immediately pressing question before the City Council will deal with water quality: What level of minerals should Tucson Water be delivering to its customers?
Back in the booming 1960s, when the water company–to meet ever-increasing population demands–was beginning to drastically draw down the aquifer, which raised the prospects for land subsidence, Tucson’s groundwater was known for its high quality.
“When we came in 1971,” recalls eastside resident Reggie Barrett, “the water was good. It tasted very good with no chemical taste.”
Fifteen years ago, after Tucson Water introduced treated Colorado River water to the system via the Central Arizona Project (CAP) canal, water quality was supposed to be maintained at lower, but acceptable, standards.
Instead, chaos followed: CAP water broke pipes and wreaked havoc in thousands of Tucson homes. In addition, many Tucsonans complained about the poor taste of the water.
Barrett remembers the change clearly: “The water didn’t taste good at all, and I wasn’t pleased about what the city had done.”
In response, the City Council ordered the CAP treatment plant shut off. In 1995, Tucson voters approved the Water Consumer Protection Act, which required the recharging of CAP water. To implement this initiative, Tucson Water began planning to build recharge basins in Avra Valley.
Shortly thereafter, Tucson Water carried out a pilot test in Barrett’s neighborhood. They brought in a blend of water–part CAP, part groundwater–which had a level of total dissolved solids (TDS) less than 420 mg/L (milligrams of mineral content per liter of water) that Barrett and his neighbors found satisfactory.
The taste of water is significantly impacted by the amount of total dissolved solids–including calcium and magnesium and smaller quantities of sodium, potassium and iron–found in CAP water.
Today, by mixing groundwater with CAP water in Avra Valley and then blending it further with other well water throughout its distribution system, Tucson Water supplies a product with TDS levels between 180 and 560, while averaging 386.
That output cannot be continued indefinitely, because the CAP water naturally has a TDS level around 650.
Within a few years, as CAP water replaces groundwater in Avra Valley, it is projected the Tucson Water level will rise to 450, and then reach 650 by 2020.
A few years ago, in an effort to determine what quality of water its customers wanted and were willing to pay for, Tucson Water conducted “Decision H2O.” Officials provided people at mall kiosks and other locations with samples of water at 450 and 650 TDS levels, and participants picked which they preferred.
Those taking this taste test were told the average water bill–which was then $19 per month–would rise to $33 under the 450 TDS option, because of the enhanced filtration required. The monthly bill for the 650 TDS alternative was estimated to increase only to $26 by 2015.
Because of its higher mineral content–which would probably drive up demand for bottled water and water softeners–the 650 TDS level would do more harm to plumbing and household appliances. For instance, one Los Angeles study determined that raising TDS from 400 to 600 decreases the useful life of water pipes from 26.6 to 22.2 years.
This same report also concluded that water with a high TDS level causes “scaling and spotting, reduced lifespan of appliances and greater use of cleaning products such as soap and detergent.”
For its part, Tucson Water estimates these negative costs would run the typical customer between $3 and $4 a month.
According to Tucson Water director David Modeer, of the almost 14,000 people who took the “Decision H2O” taste test, 51 percent preferred the 450 level, while 35 percent picked the 650 TDS water. The remainder were satisfied with either.
To consider the future-water-quality issue in more detail, Tucson Water then organized panels of people to look at questions of affordability, equity, community values and taste.
“They had a 50-50 ranking,” Modeer reports of the tentative panel results. “But they favor the 650 level with the breaking point being cost.”
Tucson Water spokesman Mitch Basefsky adds: “When you take and stack the factors, the cost of the 450 level has the strongest effect (on panel opinions).”
If the Tucson City Council answers the water-quality question by selecting the 650 level, not much will change in Avra Valley.
If the 450 alternative is picked, however, Tucson Water estimates the agency will need to build a $350-$400 million reverse-osmosis plant to remove minerals from the CAP water.
In addition, that treatment process would produce a lot of mineral residue, referred to as “salts.” Projections indicate that 82 tons a day of these salts would need to be placed in a landfill by 2015, a figure which would triple by 2030.
At the same time, the reverse-osmosis process would also require a large amount of electricity to force the high volume of water through filters.
While reverse osmosis has substantial environmental and economic consequences, the federal Environmental Protection Agency has established a suggested maximum guideline of 500 for total dissolved solids in drinking water. The agency emphasizes that while there are no health risks associated with exceeding this figure, there are other household ramifications.
However, UA associate research scientist Martin Yoklic notes that whether solids are removed at a reverse-osmosis plant or go into the water supply and out people’s taps, “it doesn’t matter where you do it; (those solids eventually are) going on land somewhere.”
Yoklic is involved with one aspect of an ongoing study looking at an alternative to distributing high levels of CAP-carried salts to everyone. Being conducted by four water companies–Oro Valley, Metro, Marana and Flowing Wells–the goal of this research is to figure out how to remove much of the material at a proposed slow sand-filtration/reverse-osmosis facility, to be located near Tangerine Road and Interstate 10.
While Tucson Water customers have been receiving a combination of CAP and groundwater for several years, people being served by these northwest-side companies have continued to drink straight from the aquifer. That situation, though, will be changing.
According to Chris Hill, deputy manager of the Metro Water Company, the objective of the CAP pilot project is straightforward: “To maintain TDS and hardness levels,” Hill says. “That’s where the challenge lies.”
Hill is project manager for the study and indicates that the groundwater Metro now pumps has a TDS level around 350. Since the company has contracted to introduce CAP water into its system, the study is looking at a phased facility, which could begin initial operation as early as 2012, to keep the TDS level constant.
Hill estimates the cost of the filtration processÑalong with individual water-conveyance systems–might run between $180 million and $300 million, which would be divided up among the four companies. He acknowledges that would have rate impacts, but he doesn’t know how much. He also indicates that the study is looking at using renewable energy as a power source.
Philip Saletta, of the Oro Valley water utility, states that their water currently has TDS levels between 100 and 150. “With the future CAP water-treatment facility,” Saletta says, “it’s projected to be 300-400 TDS. Most palates don’t notice that difference.”
The water from this proposed northwest-side water-treatment facility will taste better than the higher-TDS alternative being considered by Tucson Water, while also doing less household damage. But it obviously will cost more, too, and the salt issue remains under study.
Back in Tucson, eastside resident Barrett remains concerned about his possible future water supply. “If the city is thinking of going to a 650 TDS level, that’s going the wrong way.”
Barrett adds: “Somewhere down the line, we’ll have to do something, but we ought to catch it in the early stages rather than let it go until it costs even more. In the long haul, keeping that level low will pay off.”
Acknowledging he already has a water softener and osmosis filter in his home, Barrett observes: “Whatever they do, I suppose we’re OK. But what about the rest of the people who can’t afford it, and people in apartments? What are they going to do?”
On the other hand, Modeer labels the TDS issue as one of “aesthetics.” He also says of Oro Valley and the other communities on the northwest side: “The social issues are different, as are the economic ones.”
There is also another difference. The Town of Oro Valley will be paying for its share of this proposed CAP treatment process, in part, through higher impact fees on growth.
“New development,” Saletta says, “will pay for their own water through (water) impact fees. They’re $1,300 a house now, and will be $5,182 per house by 2011.”
The Tucson City Council, however, hasn’t taken a similar step to boost impact fees. Modeer says the state Legislature changed the rules for impact fees since Oro Valley adopted its requirement. Because of that, Tucson Water is now working with a consultant to come up with a system of “forward-looking” water-impact fees which meet current legal standards.
As a result of the potentially divergent paths being taken toward filtering CAP water, within a decade, Tucson Water and its utility neighbors to the north could end up providing water with substantially different qualities. If that happens, what some might call a water-quality ghetto could be created in the center of the community.
In any case, water-utility customers in both places are facing the same economic questions: They will either pay more to filter CAP water, or pay more as a result of the household damage caused by higher TDS levels.
Either way, we’ll all be paying more because of CAP water.
In the communities south of Tucson, salt in the water has yet to become a serious issue. Instead, they’re facing another problem: How will they pay to have the CAP canal extended to Green Valley from its present termination at Pima Mine Road?
Much attention has been given to the offer by Augusta Resource Corporation–which is proposing the Rosemont copper mine nearby–to pick up part of the estimated $120 million tab for extending the canal. In any case, Arturo Gabaldon, of the Green Valley Community Water Company, says CAP water will probably need to be introduced to the area.
“Our water table has declined substantially,” Gabaldon says. “We also have water-quality issues to deal with as a result of (copper-mine) tailing ponds. Some of our wells have been tainted.
“It’s not should we have a pipeline” of CAP water, Gabaldon says. “It’s irresponsible not to have this source.”
As for the quality of that CAP water, Gabaldon says: “You understand the value of water when your well runs dry. … The 600 level of salts coming out of my well is a lot better than no well at all.”
Of course, Green Valley is not alone when it comes to concerns about wells running dry.
The seven states which border the Colorado River have divided up 16.5 million acre-feet (325,851 gallons equal 1 acre foot) of its water on paper, but only about 13 million actually flows now. At the same time, because of global climate change and other factors, that number is predicted to drop–possibly sharply.
Kathy Jacobs, director of the Arizona Water Institute, says climate change is no longer debatable. “It is better to error on the conservative side when it comes to water management now. … We can no longer assume that the future is going to be like the past.”
An article authored last year by Brad Udall, of the University of Colorado’s Western Water Assessment project, summarizes the findings of several studies which examined future flow on the Colorado River. Under the most likely climatic scenarios, these studies predict that over the next century, runoff into the river is expected to shrink between 11 and 45 percent.
Then there is the dramatic forecast predicted by Scripps’ scientists, Barnett and David Pierce. Using a conservative global-climate model–predicting a 20 percent decrease in the flow of the river by the end of the century–they have concluded there is a 10 percent possibility Lake Mead could basically dry up by 2014; by 2021, the chances go up to 50 percent.
“What brings us to this startling conclusion,” Barnett says, “is that our water-budget analysis has factored in not just current evaporation, but future evaporation and infiltration.”
Barnett is hoping the report will be a wake-up call for growing Southwestern cities.
“We don’t mean for people to get hung up on particular dates,” he explains. “What we’re saying, bottom line, is that maybe we have 10 years to deal with this. And the big question is: Is anyone going to do it?”
Recent data coming out of the UA’s Laboratory of Tree-Ring Research backs up the need to take the current drought extremely seriously. In a recent National Geographic article on the Colorado River, more than a few scientists using that research concluded: “The wet 20th century, the wettest of the past millennium, the century when Americans built an incredible civilization in the desert, is over. … The West is naturally dry, but just how dry it can get is only now being understood.”
If these projections are correct, that could result in a potential catastrophe for those communities, like Tucson, that depend heavily on the Colorado River for water.
While Arizona’s water planners haven’t accounted for the alarming forecast by Barnett and Pierce, they have taken into account some major reductions in flow. The state currently receives approximately 1.5 million acre-feet of Colorado River water, with Tucson Water’s share being 144,000 acre-feet.
Modeer is an elected member of the Central Arizona Water Conservation District (CAWCD) board, which oversees the state’s CAP operation, and says he is leaning toward running for re-election later this year. The Tucson Water director points out the CAWCD has factored into consideration the possibility of a shortage of Colorado River water being declared by the U.S. secretary of the interior.
“If a shortage is declared,” Modeer says, “Arizona will take a 350,000 acre-feet cut. But there is now 600,000 acre-feet in excess, because those who contracted for the water aren’t fully utilizing it. These are mostly Native American communities which have 49 percent of the total allocation.
“Last year,” Modeer continues, “projections were the shortage would be declared in 2011 … It’s likely to last 10 to 15 years, but municipal and industrial users (of CAP water) are fairly safe for 20 to 25 years.”
Depending upon who is asked, Tucson’s future water supply may or may not be secure. At the same time, the quality of water in a river with a lower flow is also questionable. With less water in the Colorado, could TDS levels rise accordingly?
Jim Prairie works for the U.S. Bureau of Reclamation in Colorado and says that projects along the river have successfully reduced the TDS level somewhat. Despite that, he concludes: “As the river flow drops, we’ll see increased salinity, but it’s not a linear relationship. With the drought, we’re not seeing dramatic increases in TDS.”
In the short-term, the TDS issue hangs over all local water providers who have banked on CAP water. But another question is even more serious: How much growth can be risked on a dwindling Colorado River?
What the Tucson City Council and other local water providers do to answer that question will guide community planning for decades to come. If the decision is to continue business as usual, the result could be disastrous for Tucson.
Questions that need to be answered:
1. Is metropolitan Tucson’s current water situation sustainable? If it isn’t, what should be done about it?
2. How low in quality should Tucson Water go?
3. Should limitations on population growth, strict mandatory conservation measures and the capture of storm-water runoff all be seriously considered by local elected officials when planning the region’s future?
4. Will the Tucson City Council–saying they have no choice if unlimited growth is to continue–eventually accept the use of treated effluent for drinking-water purposes?
5. Given the variability of predictions, should local water managers be erring more on the conservative side when it comes to projections of Tucson’s future CAP amounts?
6. How would Tucson’s economy be affected if the city has a less-desirable quality of water than surrounding communities?
7. What long-term studies have been conducted about the health effects of higher TDS levels?
Molly McKasson served on the Tucson City Council between 1989 and 1997. Both she and Dave Devine supported adoption of the Water Consumer Protection Act.