Open Air Reservoirs and Your Health

Even though it seems as if Portland’s elected officials have capitulated over the covered reservoir ordinance (EPA Long Term 2 Enhancement Surface Water Treatment–LT2), a group of concerned citizens believe there is still time to inform the public and change this expensive and unnecessary course of action.

Mt. Tabor Reservoir 6 empty possibly forever?

Since first learning about the removal of one of our icons, the Mt. Tabor reservoirs, along with all its implications, The Southeast Examiner has been reporting this process.

Over the next few months, we will revisit this information and other relevant material in a series of articles to address:

• the Environmental Protection Agency’s (EPA) national one-size-fits all LT2 regulation;

• the facts on cryptosporidium;

• the benefits of open air reservoirs;

• the type of UV device they are going to use for the covered reservoirs:

• future drinking water–combining the Willamette, Columbia and Clackamas Rivers with pristine Bull Run water;

• the real costs and who’s going to profit.

Citizens can still take action. See “Contact” page for more information and actions.


PART 1: Health benefits of open water reservoirs

The deep open water reservoirs of Mount Tabor and Washington Park provide many public health advantages.

In an open reservoir, gases that occur naturally like radon and those that are part of the disinfection process, i.e. chloroform, can harmlessly escape into the air before entering indoor environments.

Radon, from the Columbia South Shore Well field, has been found in our drinking water at various levels. It is a gas formed from radioactive decay of soil and granite rock material. It is odorless, colorless, and easily transfers from water to air through showerheads, water faucets, toilets, washing machines etc., where it can be inhaled or ingested.

A storage tank left open to the atmosphere, such as Mt. Tabor’s open reservoirs, will rapidly lose radon through diffusion into the air and other natural decay. Open-air reservoirs are the only efficient method of removing unwanted gases.

The Portland water system currently uses a chemical disinfectant known as chloramine (NH2C1). It is commonly used in low concentrations as a disinfectant in municipal water systems as an alternative to chlorination because it is much more stable and does not dissipate as rapidly as chlorine.

In an open-air reservoir, sunlight breaks down n-Nitrosodimethylamine (NDMA), a byproduct of chloramine disinfection and a suspected carcinogen. Sunlight also inhibits the breakdown of chloramine residuals from nitrification bacteria and subsequently the formation of nitrate and nitrite.

Increased levels of nitrate and nitrite can result in blood, gastric, and other serious health disorders. (1)

While disinfectants are effective in controlling microorganisms and necessary to prevent diseases, they react with natural organic and inorganic matter in source water and distribution systems to form unwanted by-products.

These chemical compounds are called Trihalomethanes (THMs). Because we have no sewage exposure in the Bull Run water system, disinfectant by-products are well below EPA standards. However, they still need to be vented.

In our open-air reservoirs, oxygenation from the motion of the fountains and waterfall action at the inlets, provide additional disinfection similar to how ozone works.

Increased activity close to the water’s surface releases oxygen that can kill anaerobic organisms. (Anaerobic requires an absence of oxygen.) The difference can be compared to a fast flowing river versus a pond. The dissolved oxygen in open-air reservoirs allows aerobic bacteria to further break down unwanted organic materials.

The permanent burial and floating covers of the nation’s reservoirs may not provide the true public health benefit the EPA says. Covered reservoirs do not vent disinfection by-products.

Plastic covers proposed in the past will shrink, crack and deteriorate over time. As these materials breakdown into the water, the by-products will be consumed. Animals can still get into these buried reservoirs to nest and contaminate the water. Biofilm will develop under the surface of the containers. Algae will likely develop around the perimeter and off-flavors and odors can be expected.

The Bull Run reservoirs have no agricultural, industrial or municipal use surrounding them unlike New York City’s water where their system travels from their watershed in the Catskill Mountains through hundreds of miles of agricultural land, open reservoirs and rivers before reaching residents.

The elected officials and citizens of New York were able to get a deferral to covering their Hillview reservoir until 2028 or longer. New York now seeks an EPA waiver.

Currently New York is designing a comprehensive watershed protection strategy to target any sources of pollution, i.e. inadequately treated wastewater, wildlife (especially waterfowl), agriculture, and storm water runoff from development.

This type of watershed program provides an alternative to expensive end-of-pipe  treatment such as the one we are being forced to pay for even though we don’t have agricultural or human wastewater runoff.

Because Bull Run has been federally-protected from human entry for the last 100 years, our risk from illness is not even measurable.

In the next few years, there will be another increase of more than 40 percent on our water bills. This is needed to pay for the $253 million bond offering the Portland Water Bureau received in April 2013 to continue building our unnecessary new LT2 related structures and possibly an artificial UV treatment plant at Bull Run Head Works.

All of this for a public health problem that does not exist.

We do not live in a sterile world and the open reservoirs expose us to nothing more than we are already subjected to in everyday living.

The sunshine and open air waters break down and vent gaseous chemicals, reflecting the natural functioning of a healthy water system. Covering or burying our reservoirs will give radon and the trihalomethane disinfectant by-products nowhere else to vent except our homes, our schools and our businesses.


Footnote 1. The increase in nitrification episodes associated with covering previously uncovered reservoirs within chloraminated systems was not discussed or provided for in the Long Term 2 Enhanced Surface Water Treatment Rule literature. 

Information in part by Scott Fernandez, M.Sc. Biology/Microbiology







































































































Open Air Reservoirs and Your Health

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