Tucson water

EPA may change Dioxane standards in Tucson water

As the Arizona Daily Star reported today, the EPA is considering lowering the allowed concentration of dioxane in drinking water. That would cost the city millions to build a new water purification plant.

Current EPA standards allow up to three parts per billion. Tucson Water mitigates some contaminated water from Tucson’s south side by diluting the water and now delivers water with 1.15 parts per billion dioxane. The EPA says that under current standards, drinking the water for 70 years would give you a one in 1 million chance of getting cancer from dioxane. That’s about the same as the chance of getting hit by lightning in the U.S.

Here’s the rest of the story:

The EPA is running into trouble over these standards from the Department of Defense and some industry groups such as the Alliance for Environmental Responsibility and Openness (AERO). AERO says that the “only studies that show … dioxane causes tumors are very high dose rodent studies.” There is no reason to assume, as the EPA does, that there is any evidence to suggest a “proportional or linear relationship between health problems experienced in rodents at high doses and those that would be expected to occur in humans exposed to the chemical in more typical environmental circumstances.”

The Department of Defense (DOD) warned the EPA that it may face challenges under the Data Quality Act because the EPA changed conclusions of peer-reviewed studies after the fact. The changes included “the number of animals, the number of animals that had tumors, the doses given to the animals, and changes in both the statistical procedures and . . . calculations,” DOD says.

What all that means is that the EPA may be mired in lawsuits before it can impose any changes.

By the way, dioxane is a byproduct of the production of materials used in cosmetics, notably sodium myreth sulfate and sodium lauryl sulfate (check your shampoo). Since 1979, the U.S. Food and Drug Administration has conducted tests on cosmetic raw materials and finished products for the levels of dioxane, and found dioxane levels up to 1410 parts per million(ppm) in raw ingredients, and levels up to 279 ppm in off the shelf cosmetic products. But EPA bureaucrats are now trying to scare us with three parts per billion.

The chemophobia of the EPA seems founded on a political agenda and upon pure guess work based in part on the “linear threshold” hypothesis. Simply stated, this hypothesis maintains that if a large dose is harmful, then smaller doses are also harmful in proportion. That is equivalent to saying that the harm from one man falling 100 feet is equivalent to that of 100 men falling one foot. This reasoning is applied to many natural phenomena and potentially carcinogenic substances to justify regulation and government programs.

Tucson’s Water Action Plan, Fuzzy Sustainable Development

The City of Tucson and Pima County are collaborating on a region water plan. It’s about time. But you should read the reports: government concepts of priorities might not be the same as those held by property owners and businesses.

Over the past several years, local governments have been devising a plan to maintain and ensure water supply for the future. A “Phase 1” report deals with an inventory of water resources and an assessment of infrastructure. A “Phase 2” report “establishes a framework for sustainable water resources planning including 19 goals and 56 recommendations within four interconnected elements: Water Supply, Demand Management, Comprehensive Integrated Planning, and Respect for Environment.”

The new Action Plan describes a range of activities with time lines to implement the goals and

recommendations in the Phase 2 Report. The City wants your comments.

From my reading of the plan, the City is placing great emphasis on making the Santa Cruz River pretty. That will include riparian restoration projects, a new bureaucracy to propose such projects, and bond elections to buy up land. The report uses fuzzy phrases such as “smart growth” and “sustainable development.” Concerning sustainability, the report admits, ” Our work during Phase I documented how elusive the concept is in practice.”

The Action Plan cites four principles for managing water:

Principle 1: Water is an essential part of life for humans and the environment. Delivery of water and wastewater must maximize both quantity and quality.

Principle 2: The environment must be considered a user, not simply a provider, of water resources.

Principle 3: Policies affecting water and wastewater must be open to wide public discussion in a completely transparent process.

Principle 4: Water is an economically-valued resource and must be managed with due consideration to its economic value.

Your comments are needed to help the City go from concepts to practice.

For some additional background, please read my posts: Water Supply and Demand in Tucson, and How Much Water is There.

How much water is there?

The answer depends in part on how much you are willing to pay. There continues to be some valid concern about our water supply. These concerns generally cite our current drought conditions and population growth. Tony Davis of the Arizona Daily Star has written a series of articles on the subject, articles that generally sound an alarm. For instance, see Tucson’s source of water runs low and Contrasting views on what to do about dwindling water .

To put such articles in perspective, however, consider this:

The Tucson area currently uses about 350,000 acre-feet of water per year. An acre-foot is 325,851 gallons, enough to supply three-to six family residences for a year (the number of residences depends on who’s doing the estimation). For that 350,000 acre-feet of current usage, we withdraw about 256,000 acre-feet from our groundwater supply. The Central Arizona Project (CAP) provides about 65,000 acre-feet and the rest is from use of effluent and incidental recharge. Natural recharge to the aquifers is about 60,000 acre-feet per year, much less than the amount we withdraw.

Estimates from the University of Arizona imply that our groundwater supply, at projected rates of usage, represents about a 200-year supply. Our CAP allocation is 314,000 acre-feet per year. That would seem to cover our needs, but the CAP supply is subject to natural variation of droughts, and the whims of politics. For more details, please read my blog from last June: Water Supply and Demand in Tucson. For a perspective on droughts, see my article: Drought in the West.

Our CAP supply is drawn from the Colorado River. Currently our Colorado River reservoirs stand at 55% capacity, the same as last year at this time. We are not gaining on the amount stored because water released for electrical generation and river health about equals inflow to the system. See: Bureau of Reclamation weekly water report. See also: Bureau of Reclamation forecasted use for 2010. In contrast, the Salt River system, supplying Phoenix, stands at 97% capacity. The BR report says that our “water year” precipitation is 82% of normal in the Colorado River basin and 122% of normal in the Gila River system. Snowpack is put at 83% and 244% respectively.

The point of this article is that our water policy must be based on facts rather than on perceptions. Conservation measures must also be based on facts rather than on “feel-good” ideas of the day.

The groundwater supply mentioned above counts just the aquifers down to about 1200 feet, but depth to bedrock in the Tucson and Avra Valleys is as much as 15,000 feet deep in places, so the valleys contain more water. That deeper water, however, would be more expensive to pump and process.

A related, but important concern is not just the ultimate water resource, but also the distribution system, how to get the water to the customer. Current peak summer water demand in Tucson is greater than maximum well pumping capacity of 143 million gallons per day. How much water is there? That depends on how much you are willing to pay.