USGS claims that mercury and selenium are accumulating in the Colorado River

A study conducted by the U.S. Geological Survey (USGS) claims to have found “relatively high -compared with other large rivers” concentrations of mercury (Hg) and selenium (Se) in the food web along the Colorado River between Glen Canyon Dam and the Grand Canyon, The study was done in the summer of 2008, but curiously, results were just published in the journal Environmental Toxicology and Chemistry in August 2015. Perhaps they were taking advantage of publicity associated with the toxic spill from the Gold King mine in Colorado earlier this month.

USGS Hg Se study map

Some excerpts from the press release:

“The study, led by the U.S. Geological Survey, found that concentrations of mercury and selenium in Colorado River food webs of the Grand Canyon National Park, regularly exceeded risk thresholds for fish and wildlife. These risk thresholds indicate the concentrations of toxins in food that could be harmful if eaten by fish, wildlife and humans. These findings add to a growing body of research demonstrating that remote ecosystems are vulnerable to long-range transport and bioaccumulation of contaminants.”

“The study examined food webs at six sites along nearly 250 miles of the Colorado River downstream from Glen Canyon Dam within Glen Canyon National Recreation Area and Grand Canyon National Park in the summer of 2008. The researchers found that mercury and selenium concentrations in minnows and invertebrates exceeded dietary fish and wildlife toxicity thresholds.”

“Although the number of samples was relatively low, mercury levels in rainbow trout, the most common species harvested by anglers in the study area, were below the EPA threshold that would trigger advisories for human consumption.”

See full paper: http://onlinelibrary.wiley.com/doi/10.1002/etc.3077/epdf

From the paper:

“Sampling occurred from 12 to 28 June 2008. At each site, we collected representative basal resources (organic matter and primary producers), macroinvertebrates, and fishes. Basal resources included fine benthic organic matter, seston (suspended organic matter), epilithon (benthic biofilm), attached algae (Cladophora sp.), and epiphyton (diatoms attached to Cladophora). We collected fine benthic organic matter from sandy depositional habitats using a Ponar dredge (0.052 m2 ) deployed from a boat.”

As far as I can determine, the study analyzed fewer than 25 samples of each group along 250 miles of river. That is indeed a very low number upon which to form conclusions.

“In the present study we found no significant differences in Hg and Se accumulation among sites throughout the Grand Canyon.”

“There is a well-documented antagonistic interaction between Se and Hg, whereby Se protects animals from Hg toxicity when Hg:Se molar ratios are approximately 1 or less. The Hg:Se molar ratios were typically much lower than 1 in the present study, ranging from 0.04 (rainbow trout) to 0.38 (fathead minnow) among fish species. Assuming that Se and Hg in prey are equally transferred to consumers, this large excess of Se in this system suggests that the risks of Hg toxicity could be considerably lower than the Hg wildlife risk values alone would indicate.”

From the press release:

“The good news is that concentrations of mercury in rainbow trout were very low in the popular Glen Canyon sport fishery, and all of the large rainbow trout analyzed from the Grand Canyon were also well below the risk thresholds for humans,” said one of the study authors.

“We also found some surprising patterns of mercury in rainbow trout in the Grand Canyon. Biomagnification usually leads to large fish having higher concentrations of mercury than small fish. But we found the opposite pattern, where small, 3-inch rainbow trout in the Grand Canyon had higher concentrations than the larger rainbow trout that anglers target.”

Regarding mercury: “Airborne transport and deposition — with much of it coming from outside the country — is most commonly identified as the mechanism for contaminant introduction to remote ecosystems, and this is a potential pathway for mercury entering the Grand Canyon food web.” Selenium is derived from “irrigation of selenium-rich soils in the upper Colorado River basin contributes much of the selenium that is present in the Colorado River in Grand Canyon.”

The paper abstract notes that “consistent longitudinal patterns in Hg or Se concentrations relative to the dam were lacking.” That would seem to cast in doubt the proposed source of selenium from upstream irrigation of agricultural land. The “relatively high” concentrations they were talking about in fish are 0.17–1.59 ppm Hg and 1.35–2.65 ppm Se.


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.


Free the Land from the Feds

The federal government owns more than 623 million acres of land, mostly in the western states. The recent defense spending bill included designation of new National Parks, Wild and Scenic Rivers, and National Heritage areas. How much land is enough?

Most federal land is administered by four agencies: the Bureau of Land management, 258.2 million acres; the Forest Service, 193 million acres; the Fish & Wildlife Service, 93 million acres; and the National Park Service, 79 million acres. Other federal land ownership includes military bases and land held in trust for Indian reservations. The map below shows the concentration of federal lands in the west.

Western federa lands

The State of Utah wants 31.2 million acres of its land back. “In an unprecedented challenge to federal dominance of Western state lands, Utah Gov. Gary Herbert in 2012 signed the ‘Transfer of Public Lands Act,’ which demands that Washington relinquish its hold on the land, which represents more than half of the state’s 54.3 million acres, by Dec. 31, 2014.” (Washington Times) We are still awaiting the outcome of this probably quixotic endeavor. But it sets a precedent and more western states should take up the quest.

Besides outright ownership, the feds are wreaking havoc on private property rights through the Endangered Species Act and the Clean Water Act.

In Arizona, for example, the right of Phoenix, the Salt River Project, and the Central Arizona Water Conservation District to divert Colorado River and Salt River water to Phoenix and Tucson is being threatened by the US Fish and Wildlife Service because those diversions allegedly endanger everything from gila topminnows, and chiricahua leopard frogs, as well as willow flycatchers.

The Town of Tombstone was forbidden to fix part of its water supply after it was destroyed in a forest fire because the source is in a wilderness area. (See Tombstone versus the United States)

The EPA and Corps of Engineers are attempting to expand the definitions in the Clean Water Act to include the most tenuous connection to “navigable waters” that would encompass private irrigation ditches, ponds, and puddles in order to gain more control over private property.

Perhaps the new Congress can address some of these abuses of federal regulations and free the land from Big Brother and allow states and private property owners to put the land to productive use.

See also:

Repeal the Endangered Species Act

Endangered Species paperwork to cost $206,098,920

Endangered species act could halt American energy boom

How NEPA crushes productivity

Forest thinning may increase runoff and supplement our water supply

Thinning of southwestern forests, partly to curb devastating forest fires, has long been a controversial subject. In general, forest thinning has been opposed by environmental groups.

Now, however, a new study (“Effects of Climate Variability and Accelerated Forest Thinning on Watershed-Scale Runoff in Southwestern USA Ponderosa Pine Forests” published October 22, 2014) conducted by The Nature Conservancy and Northern Arizona University recommends accelerated forest thinning by mechanical means and controlled burns in central and northern Arizona forests. The study estimates that such thinning will increase runoff by about 20 percent, add to our water supply, and make forests more resilient. You can read the entire study here.

Forest thinning study area

The study abstract reads:

The recent mortality of up to 20% of forests and woodlands in the southwestern United States, along with declining stream flows and projected future water shortages, heightens the need to understand how management practices can enhance forest resilience and functioning under unprecedented scales of drought and wildfire. To address this challenge, a combination of mechanical thinning and fire treatments are planned for 238,000 hectares (588,000 acres) of ponderosa pine (Pinus ponderosa) forests across central Arizona, USA. Mechanical thinning can increase runoff at fine scales, as well as reduce fire risk and tree water stress during drought, but the effects of this practice have not been studied at scales commensurate with recent forest disturbances or under a highly variable climate. Modifying a historical runoff model, we constructed scenarios to estimate increases in runoff from thinning ponderosa pine at the landscape and watershed scales based on driving variables: pace, extent and intensity of forest treatments and variability in winter precipitation. We found that runoff on thinned forests was about 20% greater than unthinned forests, regardless of whether treatments occurred in a drought or pluvial period. The magnitude of this increase is similar to observed declines in snowpack for the region, suggesting that accelerated thinning may lessen runoff losses due to warming effects. Gains in runoff were temporary (six years after treatment) and modest when compared to mean annual runoff from the study watersheds (0–3%). Nonetheless gains observed during drought periods could play a role in augmenting river flows on a seasonal basis, improving conditions for water-dependent natural resources, as well as benefit water supplies for downstream communities. Results of this study and others suggest that accelerated forest thinning at large scales could improve the water balance and resilience of forests and sustain the ecosystem services they provide.

The study also notes that in “ponderosa pine forests of central Arizona, stand densities range from 2 to 44 times greater than during pre-settlement conditions” and all that extra foliage sucks up water and loses it through evapotranspiration, thereby decreasing the availability of water for downstream users and wildlife.

Congress has authorized a program called the Four Forest Restoration Initiative (4FRI) that will accelerate the use of mechanical thinning and prescribed burns across four national forests, treating 238,000 ha (588,000 acres) in the first analysis area over the next 10 years. That program should be expanded.

Tucson transitioning to a renewable water supply

The state of Tucson’s water supply is always a concern. So how are we doing? Recently, Docents at the Arizona Sonora Desert Museum had an update by Wally Wilson, chief hydrologist at Tucson Water. The reason is that we Docents often have to explain to museum visitors what all those rectangular ponds are doing in Avra Valley just west of the museum. The following material is taken from his talk.

Tucson gets water from four sources: pumped groundwater, water transported from the Colorado River via the Central Arizona Project canal (CAP), water reclaimed from sewers, and water treated from former industrial usage (Tucson Airport Reclamation Project, TARP). Water is measured in Acre-feet (AF). One AF is 325,851 gallons and one acre-foot will serve four residences in Tucson for a year. Mr. Wilson presented the following graph on water usage (as of 2011):


Notice that total water usage has been declining and has reached the level it was in 1994.  That was surprising to me. Perhaps our conservation efforts are paying off. Mr. Wilson noted that average residential use in Tucson is about 90 gallons per day per capita (versus 200 in Scottsdale). Tucson is conserving groundwater by using more and more CAP water. This graph shows that our groundwater use has declined to what it was in 1959 in spite of our increasing population.

In 2011, CAP supplied 64% of our water while groundwater supplied 20%. The remainder was made up of reclaimed water. Total production in 2011 was 120,350 AF. In 2013, Mr. Wilson expects CAP will supply 80% of our needs allowing us to decrease primary groundwater pumping.

Below is a map of the CAP system. It consists of ponds to recharge the aquifer, wells to pump the water, a treatment plant, and a reservoir which stores 60 million gallons.


There are three recharge areas which Tucson Water fondly calls CAVSARP, SAVSARP, and PMRRP. These are the areas featuring recharge ponds filled with CAP water and wells to reclaim the water after it recharges the aquifer.

Why put the water in ponds to sink into the aquifer rather than treating it and pumping it directly to consumers? There are several reasons. When we first began to receive CAP water it was treated and sent to households, but the water wreaked havoc with some of our old plumbing. The current system is plan B and it has several advantages besides being kinder to plumbing.

Water from the ponds sinks into the ground at the rate of about 1.5 feet per day. As it travels 300- to 400 feet to the water table, soil filters out any viruses and bacteria that may be in the water. This filtering method is much less expensive than disinfecting the water in a treatment plant. The water still goes through the Hayden-Udall treatment plant for filtering and chlorination.

Some numbers: CAVSARP recharges 70,000 to 80,000 AF/year and recovers 70,000 AF/year. SAVSARP is permitted to recharge 60,000 AF/year and recovers about 15,000 AF/year. We are still ramping up to use our total CAP allocation. PMRRP is permitted to recharge at the rate of 30,000 AF/year and recovers water at 14,000 AF/year.

Tucson Water claims that it loses about less than 2% of the water due to evaporation from the recharge ponds. The overall CAP system loses about 5% of its water due to evaporation. Most of that occurs in Lake Pleasant which acts as a storage buffer between supply and demand.

Mr. Wilson says Tucson will have plenty of water through 2050 and beyond because we are banking water in the recharge system (and we still have the groundwater). Tucson Water is also pursuing additional sources of renewable water such as water owned by Indian Tribes. For more information see http://cms3.tucsonaz.gov/water .

See also my older posts on our water supply:

Water Supply and Demand in Tucson

How much water is there?

Trends in groundwater levels around Tucson

EPA war on coal threatens Tucson water supply

Arizona may have larger potable groundwater resource

Southern Arizona gets about 43% of its water by pumping groundwater aquifers.  The geology is well-suit for this because Southern Arizona is in the Basin and Range province which contains very deep, fault-bounded valleys.  In some places, bedrock is as much as 15,000 feet below the surface.   Portions of the Tucson and Avra valleys are over 8,000 feet down to bedrock.  Such valleys are filled with alluvium and water.


Currently, water for drinking exploits aquifers down to a depth of about 1,200 feet.  Generally water below that depth is too salty for drinking.

Following up on two previous studies, Estimated Depth to Bedrock in Arizona and Preliminary evaluation of Cenozoic Basins in Arizona for CO2 sequestration Potential, the Arizona Geological Survey in a new study, examined the salinities of Arizona groundwater.  The study is A Summary of Salinities in Arizona’s Deep Groundwater, Arizona Geological Survey Open-File Report, OFR-12-26.

As part of that study, geologists of the Arizona Geological Survey (AZGS) reviewed geophysical well logs to catalog the concentration of total dissolved solids (TDS, i.e., salinity) of 270 water wells.  This included all water wells that penetrated deeper than about 2,600 feet, which is the minimum depth necessary to sequester carbon dioxide.

Among the results of that study, AZGS found that on the Colorado Plateau and in the Basin and Range province, there are some areas where “Fresh water can extend as deep as 5,000 feet (1,500 m), but below 6,600 feet (2,000 m) only brackish or saline groundwater was encountered..”   Water is considered “fresh” if it contains less than 1,000 ppm (parts per million) TDS.  Water is “brackish” if TDS are 1,000- to 30,000 ppm.  “Saline” water contains greater than 30,000 ppm TDS.  Sea water is about 35,000 ppm TDS.

This means that we may be able to extract drinking water from deeper aquifers in some areas.

See also:

Water Supply and Demand in Tucson

How much water is there?

Trends in groundwater levels around Tucson

Tombstone versus the United States

TombstoneAllenStTombstone, Arizona, “the town too tough to die” just might be killed off by the US Forest Service. Tombstone gets most of it water supply from springs in the Miller Canyon Wilderness Area in the Huachuca Mountains about 25 miles west of the town. This water supply dates from 1881 when it was first developed by the Huachuca Water Company. Tombstone bought the pipeline and water rights in 1946.

In the early summer of 2011 the massive Monument wildfire denuded the eastern part of the Huachuca mountains. With vegetation destroyed, subsequent heavy monsoon rains caused flooding, mud slides, and debris flows that buried springs and crushed waterlines, thereby shutting off the main water supply to Tombstone.

Since that time, the City of Tombstone has tried to repair the damage, but has been stymied by a very obstinate Forest Service who will not allow heavy equipment into the wilderness area, even though the water rights pre-date establishment of the Wilderness Act.

According to the Goldwater Institute, who are suing the US Forest Service on behalf of the City of Tombstone, “Tombstone’s pipeline is under 12 feet of mud, rocks and other debris; while in other places, it is hanging in mid-air due to the ground being washed out from under it. In response, federal bureaucrats are refusing to allow Tombstone to unearth its springs and restore its waterlines unless they jump through a lengthy permitting process that will require the city to use horses and hand tools to remove boulders the size of Volkswagens.”

This is a case where bureaucratic regulations make no common sense and put citizens in danger even in spite of the fact that the City of Tombstone and the governor of Arizona declaring a state of emergency. The Goldwater Institute says, “The 10th Amendment protects states and their subdivisions from federal regulations that impede their ability to fulfill essential health and safety functions. Just as the federal government cannot regulate the States, it cannot regulate political subdivisions of the States, like the City of Tombstone. And despite what power it may claim, the Forest Service certainly has no power to regulate Tombstone to death.”

As water law expert Hugh Holub once wrote: “Though the water may originate on National Forest lands, Bureau of Land Management lands, and other federally managed lands, the rights to that water belongs to the farms and ranches and cities.” It seems that the Forest Service is ignoring that right.

The Forest Service has been portrayed as the villain here and perhaps they are. But maybe, they too are trapped by an inflexible process intrinsic to environmental laws such as the Wilderness Act and the Endangered Species Act, a process that makes timely, common sense responses to emergencies very difficult if not impossible.

See also:

Red Tape Rising – Federal Regulations Choke Economy

Repeal the Endangered Species Act

Red Squirrels and Green Dollars

Do we need the US Forest Service?

Radium in drinking water

The U.S. Geological Survey (USGS) has conducted a study of naturally occurring radium in drinking water.  They found that elevated levels of radium occur most often in the central and eastern part of the country, see map.


Radium forms from natural radioactive decay of uranium and thorium in rocks and sediments derived from those rocks.  “Most rocks and sediments contain some uranium and thorium and, thereby, contain radium as well, but usually in small quantities. Uranium and thorium are most common in granitic and metamorphic crystalline rocks and in associated weathered sedimentary deposits in the central United States and mountainous regions of the East and West.”

Major findings from USGS report:

Concentrations of radium in principal aquifers used for drinking water throughout the United States generally were below 5 picocuries per liter (pCi/L), the U.S. Environmental Protection Agency maximum contaminant level (MCL) for combined radium—radium-226 (Ra-226) plus radium-228 (Ra-228) —in public water supplies. About 3 percent of sampled wells had combined radium concentrations greater than the MCL.

The highest concentrations of combined radium were in the Mid-Continent and Ozark Plateau Cambro-Ordovician aquifer system and the Northern Atlantic Coastal Plain aquifer system. More than 20 percent of sampled wells in these aquifers had combined radium concentrations that were greater than or equal to the MCL.

Three common geochemical factors are associated with the highest radium concentrations in groundwater: (1) oxygen-poor water, (2) acidic  conditions (low pH), and (3) high  concentrations of dissolved solids.

The USGS notes: “Exposure to radium over long periods of time can increase the risk of cancer….Radium in the body behaves similarly to calcium and can replace calcium in tissues, particularly bone…Radiation exposure from radium received externally through washing, showering, or other uses of water is less of a concern since human skin tends to block exposure to alpha radiation and minimize penetration of beta radiation.”

Note that the USGS sampled only 1,266 wells nationwide and only 3% of those contained radium concentrations above the MCL.

Arizona State Geologist Lee Allison notes in his blog that “the water wells tested in Arizona are all below 1 picocurie per liter. However, only a handful of wells in Arizona were tested, all in alluvial aquifers in the south. No tests are reported from the Colorado Plateau, which has some of the highest concentrations and largest deposits of uranium in the nation.”

On an individual household level, radium is removed by ion-exchange (salt recharged) water softeners.

See a USGS fact sheet here.

Do magnetic or electrical water treatment devices really work?

Tucson has “hard” water which produces scale in pipes, on faucets, around the sink and shower, film on glass shower doors, and makes washing more difficult because soap doesn’t work as well in hard water. The “hardness” is due to dissolved calcium, magnesium, and iron in the water.

Standard treatment to remove the dissolved minerals include ion-exchange which requires recharge with salt, and reverse osmosis which filters out the offending minerals. If you search the internet, you will find thousands of wesbsites promoting magnetic or electrical wrappings for the water pipes that are claimed to rid you of hard water problems. On February 15, the Arizona Daily Star ran a full-page ad promoting one of these devices.

These products generally include strong magnets or coils of wire that are supposed to induce a magnetic field in the water. These devices do not remove calcium or magnesium (and they so admit). Instead, it is claimed the magnetic (or electrical) fields work by causing the dissolved minerals to “crystallize” or clump together and so remain in suspension rather than adhering to pipe walls and fixtures. It is further claimed that these devices can remove scale already built up in your pipes.

So do these devices really work in home applications? As far as I can find out, laboratory testing shows these devices to be ineffective in home use. In industrial applications, there is some beneficial effect under very specific conditions.

A summary of research is given by Wikipedia:

“Magnetic water treatment (also known as anti-scale magnetic treatment or AMT) is a proposed method of reducing the effects of hard water, as an alternative to water softening. Vendors of magnetic water treatment devices have claimed that powerful magnetic fields can affect the structure of water molecules or the properties of solutes passing through the magnetic field, thus eliminating the need for chemical softening agents. Only the effective hardness is claimed to be altered; no solutes (such as calcium or magnesium) are removed from the water by the process.

 Most scientific studies do not support these claims and suggest that magnetic water treatment may be ineffective.”

In 1996, Consumers Reports tested one device promoted for home use. Consumer Reports installed two new water heaters in a staffer’s house. One was supplied with untreated water, the other with water “treated” with a magnetic device. After two years and 10,000 gallons of water, the heaters were cut open and found to have the same quantity and texture of scale. CR reported the tested device ineffective.

Also in 1996, Lawrence Livermore National Laboratory, under contract from the EPA, tested a “commercial device” at a government facility. They found “No beneficial effect was found when using the magnetic device.”

A 2000 report from the Army Corps of Engineers reports on testing magnetic devices. They conclude: “The attached document provides an evaluation of current magnetic water treatment technology. Scientific literature is reviewed and summarized and several devices are tested forscale prevention. In summary the magnetic water treatment devices were not effective for scale control.”

Some other findings from the Corps of Engineers testing:

There is no effect on the rate of pipe corrosion. There were no effects on “measurable water quality parameters.” There was no significant difference in the amount or composition of scaling. “The findings do not support the claims of the manufacturers regarding the ability of their respective devices to prevent mineral scale formation in hot potable water systems.” “There was no discernible effect on the crystalline structure of the scale formed by any of the tested devices.” The crystal structure was tested because some manufacturers claim their devices change the crystal structure of the calcium carbonate into a more benign form.

Another good reference is a 2011 paper by Stephen Lower, a retired physical chemistry professor at Simon Fraser University, Burnaby BC Canada. Note that this paper appeared in Water Technology® Magazine, a trade paper for water treatment professionals. This is a good background article which explains how “hard” water is formed, and treated. Lower’s paper concludes:

“The lack of credible scientific support for the efficacy of present-day PWC [physical water conditioning] devices stands in stark contrast to the claims made by most vendors (and even some users) of these products. Given the potential economic benefits of a widely-applicable chemical-free softening process, especially in arid regions, such as the U.S. southwest, one would expect much more scientific and engineering support for the claims that have been made.”

Lower does note “a study published in a South African technical journal that describes a series of experiments in which one of two parallel heaters was fitted with a permanent magnet device showed scale formation reductions varying over a rather wide range (17-70 percent), with an average of 34 percent.”

“Still, science is never complete, and if qualified investigators could be motivated to follow up on some of the more well-founded leads that have appeared in the literature, it is possible that some of these PWC technologies could be shown to be effective, although almost certainly under very constrained conditions.”

Finally, a short paper from Pennsylvania State University concludes “There is virtually no valid scientific data to support any water treatment benefit from magnetic devices.” And “The claims put forth by manufacturers and sales representatives of these devices are without validity.”

Several of the studies note that scale formation reduction depends heavily on water temperature and flow rate.

My take on all this is: buyer beware.

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.



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.