recharge

How Tucson Water spends Conservation Fund money and a suggestion for a better way

If you are a Tucson Water customer, you may have noticed an item on the back page of your water bill listed as: “CONSRV FEE $.07/CCF.” This means you are contributing seven cents per cubic foot of water used to a conservation fund. That may not sound like much, but according to an article by Tim Steller, that added up to $2.95 million last year. By the way, this “contribution” to the conservation fund will rise to eight cents per CCF on July 15.

So, how is that money being used? The answer to that question is the objective of a Freedom of Information (FOIA) request filed last January by Mark Lewis, one of five members of the City’s Conservation and Education Subcommittee of the Citizens Water Advisory Committee.

Tucson Water has to date refused to provide the information requested by Mr. Lewis. According to Mr. Lewis, the information requested is “to gather the documentation and information necessary to ensure the funds collected from Tucson Water customers under the Conservation Fee program has been properly accounted for, audited, and expensed.” Mr. Lewis has expressed concern, in his role as an appointed advocate for the Rate Payers of Tucson Water, that the millions of dollars which have been spent through this fund have not been properly tracked or audited and that more recent uses of this fund are not consistent with the purpose of the fund: conserving water.

One conservation program promoted by Tucson Water is the replacement of old toilets with new low-flow models. Tucson Water will give you a $75 rebate toward the cost. According to Steller’s article, “water-wasting toilets remain in around 150,000 Tucson homes, and the program to replace them saved almost 11 million gallons in the first eight months of this fiscal year alone.” Mr. Lewis supports this program, but points out that the small rebate may be insufficient, especially for older homes which may have complicated plumbing issues that would make replacement more expensive.

Another conservation program is rainwater harvesting. Tucson Water will provide a rebate of up to $2000 for installing a system. Steller points out that “those rebates have mostly benefitted wealthier residents and so far have resulted in no measurable reduction in water use.” Mr. Lewis notes that the $900,000 in rain water rebates to date saved no water, but had the same money been spent on wasteful toilets it would have saved 173 million gallons of water to date.

You can read about the program in a brochure provided by Tucson Water: http://www.tucsonaz.gov/files/water/docs/Rainwater_Harvesting_Rebate_brochure.pdf

In that brochure, Tucson Water claims that “45% of the water we use goes to outdoor irrigation.” That number surprises me; I wonder if it is true. The brochure also notes that in order to qualify for the rebate, you have to take a free class. And here is where it gets interesting.

The qualifying class is run by Watershed Management Group, a consulting firm that, for a fee, will design a rainwater harvesting system for you. Three board members of Watershed Management Group, Catlow Shipek, Mark Murphy, and Amy McCoy, comprise three of the five members of the City’s Conservation and Education Subcommittee of the Citizens Water Advisory Committee. The classes are also given by a company that sells rain gutters according to Mr. Lewis. This situation has the appearance of crony capitalism and conflict of interest.

There is another scheme afoot. Tucson City Councilwoman Regina Romero has proposed that $300,000 be used to provide interest free loans to low-income residents so they can plant trees and have them watered by rainwater harvesting systems. Romero is concerned about the “unequal distribution of tree canopy in Tucson…” and its effect on the Urban Heat Island Effect (cities are warmer than surrounding countryside because all the asphalt and concrete absorb heat which makes nighttime cooling much slower). I see two potential problems with this scheme. First, we would have to cover a large part of the city with trees to have any significant effect. Second, all those trees will transpire water, losing moisture to the atmosphere rather than conserving water for reuse.

Given the information above, do you think your forced subsidy is being well-spent?

I have a suggestion on how the money could be spent to actually conserve water.

One of the eco-fads promoted by Tucson Water is rainwater harvesting at residences. So far, that program has resulted in no measurable reduction in water use. But perhaps, if that idea was used on a larger scale, it could help recharge our aquifers. Why don’t we collect storm-water runoff from city streets and in ephemeral flows in the Santa Cruz River and pump that water back into the aquifers via dry wells?

That idea is discussed by Chuck Graf, Senior Hydrologist, Arizona Department of

Environmental Quality in a short article in the Spring Issue of Arizona Water Resource Newsletter (link to article).

This idea is not new. Phoenix began recharging storm-water in the 1930s and now has more than 50,000 wells in operation. Many other communities also use this recharge method. Why not in Tucson and Pima County?

The practice of dry well recharge in Phoenix went largely unregulated until 1987 when legislature directed the Arizona Department of Environmental Quality (ADEQ) to license dry well installers and establish a registration program for existing and newly constructed dry wells. The law expressly limited the use of dry wells to the disposal of storm water. This limitation was intended to prevent disposal of hazardous chemicals into dry wells, which in the past had caused severe groundwater contamination plumes (some of which are still under remediation).

Graf explains the dry well method as follows:

“The dry well borehole is drilled in alluvial sediments, through any intervening fine-grained and cemented zones, into a permeable layer of clay-free sand, gravel, and cobbles. The permeable layer serves as the injection zone for the storm water. ADEQ requires at least 10 feet of separation between the bottom of the injection zone and the water table. Because groundwater commonly occurs at great depth in Arizona’s alluvial basins, installers often have considerable leeway to find an exceptionally permeable zone above the water table that maximizes dry well performance while maintaining a much greater separation distance than the 10-foot minimum.”

Graf goes on to write:

“Potential adverse groundwater quality impact is the biggest concern about dry wells. Although the definitive water quality study probably remains to be done, a number of studies, including a 10-year study in Los Angeles conducted by the Bureau of Reclamation and others, found little evidence for groundwater contamination. A 1985 study in Phoenix found that dry wells had a beneficial effect on groundwater quality with respect to major chemical constituents”

This idea should be considered. Perhaps then, our involuntary contribution to the “Conservation Fund” would actually conserve some water.

END

Trends in groundwater levels around Tucson

A story in the Arizona Daily Star notes that depletion of our groundwater supply is diminishing in some areas due to use of CAP water (water imported via canal from the Colorado River).  Much of the CAP water is being used to recharge the groundwater aquifer.  The maps below show the state of the aquifer levels for the periods 1970-1979 and 2000-2008.  On the maps, red indicates a falling water table, blue indicates a rising water table, and yellow indicates a stable water table.

Trends-TAMA-1970-1979

Trends-TAMA2000-2008

The data come from the U.S. Geological Survey.  See an overview page here, and an interactive map page here.

The maps show that the recharge project in Avra Valley and retirement of central city wells have made quite a difference.

Note that USGS provides this disclaimer: “All information on this website should be considered provisional and subject to revision. No judgment on the presence or availability of ground water should be made on the sole basis of information on this website. Neither the USGS nor ADWR will be held responsible for any loss or damages due to the use of this information.”  Comforting, isn’t it.

According to the Star story: “the city this year will put into the ground 140,000 acre feet of CAP water and take out 80,000. This has raised the water table 9 feet a year at the city facility in the central Avra Valley facility for the past decade and 140 feet in the three years that a second city recharge facility and well field has existed in the southern Avra valley.”

Back in 2009 I posted an assessment of Water Supply and Demand in the Tucson area based on information from  the Water Resources Research Center at the University of Arizona (WRRC). I summarize from that post here:

The Demand:

In 1999, total usage in the Tucson Active Management Area was 323,000 AF according to WRRC.  Municipal usage was 154,000 AF which included 17,000 AF used by golf courses (35% was effluent from the sewer plants), and 20,000 AF used by “turf” facilities such as parks, schools, cemeteries (33% was effluent).  Agriculture used 132,000 AF (of which 20,000 AF came from imported CAP water).  Mines used 39,207 AF, sand and gravel operations used 5,167 AF and “other” industrial use totaled 4,026 AF.  Sewer treatment plants produced 70,000 AF per year and are projected to produce 115,000 AF by 2025.  Currently 84% of effluent discharge is released into the Santa Cruz river channel where it infiltrates into a shallow aquifer.  (Alert readers might notice that these official figures from 1999 add up to more than 323,000 AF, so some categories must have been counted twice.)

By 2003, total usage increased to about 350,525 AF.  This is projected to rise to 396,000 AF by 2025 assuming increased municipal and industrial demand, and decreased agricultural use.  Natural recharge provides only about 60,000 AF per year.  In 2003, municipal usage totaled 185,199 AF.  Municipal use includes all domestic and small business consumption.  Industries used 47,430 AF; agriculture used 102,959 AF; Indians used 14,196; all others used 3,705 according to WRRC.

This total usage is about 169 gallons per day per capita, with residential use pegged at 110 gallons per day per capita, a figure that has remained constant for many years.  In contrast, the Phoenix area uses 238 gallons per day per capita, but gets 73% of its water from “renewable” resources such as rivers, CAP, and effluent.

The Supply:

In 2003, groundwater supplied 256,233 AF, CAP supplied 64,554 AF, use of effluent supplied 11,360 AF.  The rest was due to incidental and natural recharge.

Tucson gets most of its water by mining groundwater stored in aquifers down to 1200 feet deep in the Tucson and Avra Valley basins.  This is mainly fossil water deposited during the wet Pleistocene glacial periods.  However, there is even more water in deeper aquifers, but as depth increases, water quality decreases, and water becomes briny with salts and toxic metals.

The 1999 WRRC report states that, “In 1940, when Tucson began to increase its groundwater pumping, these aquifers held approximately 70 million AF of groundwater at depths less than 1,200 feet below the surface.” This resource is equivalent to all the water in Lake Mead and Lake Powell combined.  Since 1940, 10% of this groundwater has been withdrawn.  Simple arithmetic implies at that rate, the remaining groundwater supply shallower than 1200 feet could last about 150- to 200 years.  This time will be extended by increasing use of CAP water and effluent.

See my post linked above for more information.