The Blue Death Page 28
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THE FUTURE OF WATER: FROM E. COLI TO AL QAEDA
Coleridge had it almost right. For every gallon of water in the world, less than half a cup is fresh. All but one tablespoon of that is locked away in glaciers and the polar icecaps (global warming notwithstanding). Most of the world’s liquid freshwater lies buried below the surface as groundwater. If we want to find a drop to drink, we can, of course, follow the diviner’s twitching stick and burrow underground, but rainwater, the very essence of life, crawls slowly into the earth. It can take hundreds of years to replenish an aquifer. Growing cities ultimately must either find a source of surface water or stop growing, but they have a minute fraction of the world’s water to draw from. From each gallon, less than one drop flows freely on the surface in lakes, streams, and rivers. On that fraction of a drop, the future of water depends.
Humans have always wanted their water clean. Even Hippocrates warned of the risks of foul, stagnant waters. What has changed over time is not the desire for clean water, but the definition of clean. Before Snow and Koch, it was enough that water simply looked, smelled, and tasted clean. Snow showed us that the invisible could kill, and Koch found the invisible bacteria responsible and demonstrated the importance of removing them. With the discovery of viruses and the knowledge that something that could not be seen even under a microscope could kill us, the definition of clean changed again. Then, as scientists began to recognize the risk of toxic chemicals at low concentrations, the definition changed once more.
In December 2005, the federal government finally issued the rules on microbial risk and disinfection by-products agreed upon almost a decade earlier. On top of the reduction in allowable turbidity levels, the rules include provisions intended to define water supplies at risk for contamination with cryptosporidium, and require that those utilities test for oocysts. These changes will address some major gaps in the system and will improve the quality of our water, but the changes are evolutionary, not revolutionary. Clean has been redefined once again, but as always the question remains: what is clean enough?
The history of drinking water is a story of disaster and response. From cholera to cryptosporidium, disasters have forced inquiry and change. The inquiries have proven contentious and change has often taken years or decades, but eventually the changes were put in place to prevent the recurrence of those exact disasters. Cholera is gone from London. Milwaukee is unlikely to see another major outbreak of cryptosporidiosis. The improvements, however, have almost always looked backward. The risk we must fear most is the one we have never seen. In the uncertain future, emerging diseases, changing climates, poorly understood pollutants, decaying infrastructure, and the dark hand of terror all threaten us through our drinking water. Are we prepared? To answer this question, we must consider each element of our water supply: source water, treatment, distribution, consumers, and management, as well as the ultimate wild card, terrorism.
THE SOURCE
On a cool winter day, fleets of clouds sail in off the Pacific, founder on the rugged green mountains south of Mount Hood, and spill their cargo on the pristine wilderness below. Rain drops onto the outstretched branches of towering Douglas firs and western red cedars and filters down through the lush canopy before falling silently onto a floor of ferns and pine needles. In the Bull of the Woods Wilderness, that moisture runs across the surface or seeps into the soil, past roots and rocks to feed Bull Run Lake, one of the cleanest lakes in the United States. Twenty-five miles to the east, that pristine water flows through pipes beneath the bustling city of Portland, Oregon.
Every drop of Portland’s water falls on federal land managed by the U.S. Forest Service. A special agreement established more than a hundred years ago forbids access to the Bull of the Woods Wilderness unless authorized by the Portland Water Bureau. Only with this level of control can a watershed be fully protected. Other cities claim to have protected watersheds, but none of them can match the Bull Run.
On the other side of the continent, on an average day, the sewage treatment plant for Yorktown Heights, New York, sends 1.5 million gallons of treated sewage into the Muscoot River. This fact would be unremarkable but for the ultimate fate of the water in the river. After leaving the Muscoot, the water ambles through a series of reservoirs, descends into an aging network of pipes, and becomes drinking water for the people of New York City. Yorktown Heights, however, is far from the only sewage treatment plant in the immense watersheds that supply New York. Currently 114 communities send their wastewater into New York’s “protected” watersheds.
Sewage treatment decreases the number of pathogens in wastewater, but does not eliminate them. New York City depends on dilution and delay to reduce the health risk from the treated sewage. Any pathogens in the water are assumed to disappear in the vast reservoirs or to die before they can reach the intake pipe. New York City’s Department of Environmental Protection is so confident in its ability to protect this watershed that they do not filter the water. In other words, the only active water treatment that stands between the sewage treatment plant of Yorktown Heights and the taps of New York City comes from the pumps that feed chlorine into the water after it leaves the reservoir.
New York is not alone. A handful of other major cities around the country including Boston, Seattle, San Francisco, and Portland, Oregon, do not filter their drinking water. Instead, they rely on watershed protection and chemical disinfection to ensure the purity of their water. Even those who manage the watershed must occasionally admit that the protection is imperfect. As recently as June 2005, after a heavy rain caused a sharp spike in turbidity, New York’s health department warned city residents with compromised immune systems to boil their drinking water.
Source water protection is the bedrock of a safe water supply. Although it is possible to purify even the most grossly contaminated supply, total reliance on water treatment means that any failure of the filtration system will open the door for disaster. For those cities that own or maintain statutory control over large drinking water reservoirs and the watersheds that feed them, source water protection is at least plausible. These fortunate water suppliers can face daunting challenges as demonstrated by New York City’s “protected” watershed, but they are far better off than others such as St. Louis, Philadelphia, Washington, D.C., or New Orleans, which must contend with whatever the towns and cities upstream choose to dump into the river. Managers of the water supply for these cities can only dream of watershed protection as they stare up the river at water flowing through a complex quagmire of regulatory authorities.
In fact, most Americans drink treated sewage on a regular basis. The lakes and rivers that provide water to most large cities in the United States routinely receive treated and even untreated sewage in proportions far greater than those found in New York’s water supply. Heavy rains can send contaminated runoff and raw sewage rushing toward the intake of water supplies downstream. Dry conditions, on the other hand, reduce the amount of water available to dilute treated contaminants flowing into the lake or river. In some cities a major portion of the water they suck into their drinking water treatment plants can be treated sewage during periods when summer droughts or long stretches of icy weather reduce the amount of fresh water flowing into their water supply.
This contaminated water often flows through multiple states and within the purview of dozens if not hundreds of local governments. Without a strong federal hand, uniform protection of interstate waterways is almost impossible. Unfortunately federal regulations would have us believe that there are two different kinds of water: one, the water that receives our waste, and two, the water we drink. The Clean Water Act, designed to prevent the sort of unbridled dumping of waste that turned Lake Erie into an airless puddle and allowed the Cuyahoga River to catch fire, regulates the contaminants flowing into our lakes, rivers, and streams. The Safe Drinking Water Act defines what contaminants are permissible in the water we drink. Each act has spawned separate bureaucracies, separate scientifi
c communities, separate stakeholders, and surprisingly distinct agendas. Efforts to bridge these worlds and develop an integrated approach to our water supply have met with limited success at best.
Watershed protection will always be the most important component of any system to provide safe drinking water. Our watersheds face pressure from all sides. Growing populations increase the demand for water for all purposes. More water consumption means more wastewater, which must find somewhere to go. Larger populations also mean more industry, more agriculture, and more demand for land. All these things translate into greater threats to the purity of the water we rely on for survival.
TREATMENT
Amid the rolling hills of central Massachusetts, two men climbed into a motorboat, drove out into the middle of a large lake toward a flock of seagulls. As they approached, they pulled out a small arsenal of fireworks, took aim at the birds, and opened fire. The barrage of explosions and flames sent the birds squawking into the air. With that flock dispatched, they moved on to look for more birds. After they had finished harassing any bird they could find in the area, they returned to the dock. One might have expected the local police to be waiting at the dock for these troublemakers, but these men have never been charged, despite regular attacks on the birds in the lake. In fact, they get paid for their efforts.
From Swampscott to Hingham to Framingham, the people of the Boston metropolitan area drink the unfiltered water provided by the Massachusetts Water Resources Authority (MWRA). In 1997, after water from its protected watershed failed to meet federal standards for E. coli (also known as fecal coliform) for three consecutive years, the EPA ordered the MWRA to build a filtration plant. Having just built a massive sewage treatment plant as part of a costly effort to clean up Boston Harbor, the MWRA was fiscally exhausted. They were reluctant to return to taxpayers for more money, but their permit to provide water without filtration presumed that there was no significant fecal contamination in the water that arrived in Boston from their protected watershed. So the MWRA began preliminary planning for a filtration plant. Then after extensive research, they came upon an alternative plan to avoid filtering their water. They decided to scare the birds.
Birds, as it turned out, were a major source of the E. coli in the water supply. In the days before West Nile fever and avian influenza, one might have wondered why a bit of bird poop should threaten us, but the possible risk should now be apparent. After identifying the source of the bacteria, the MWRA concluded that it would be far cheaper to scare birds away from the intake of their water pipes than to build a filtration plant. The program for bird harassment expanded to include hovercraft, propane cannons, egg-smashing expeditions, and elaborate structures to prevent birds from nesting on rocks near the pipe that draws water out of the reservoir. This program, together with a plan to intimidate muskrats and beavers, succeeded in reducing levels of fecal coliform enough to keep the MWRA in compliance with the law.
When the EPA still insisted that they filter, the MWRA decided to fight it in court. One of their main arguments in court was that pipes in Boston’s distribution system were so old and corroded that fixing them would be a far better use of their money. Why pour clean water into dirty pipes? The safety of the water supply, they further contended, was a local issue, not a federal issue, and any decision about the best way to protect the water supply should be local. This sounds good, but as the disaster in Walkerton reminds us, local governments do not always have the expertise, resources, and political independence to make the best decisions about drinking-water safety. Boston is not Walkerton, but one can only imagine the state of America’s water supplies if Congress had left drinking-water quality as a local issue and had not passed the Safe Drinking Water Act in 1974.
The MWRA won in court, but the victory may have been Pyrrhic. If pouring clean water into dirty pipes was a mistake, is pouring water full of organic matter into clean pipes any better? The MWRA’s own estimates put the cost per household for a filtration plant at less than ten cents a day. Is that really too much to pay for an extra measure of confidence in the water supply? Why, one might reasonably ask, didn’t Boston want to have the best water possible?
Watershed protection is an essential part of providing safe water, but even the most protected watershed is not immune from contamination. In 1995 in a remote Canadian watershed, mountain lions with toxoplasmosis are believed to have contaminated the drinking water reservoir for Victoria, British Columbia. Toxoplasmosis usually begins with fevers, rashes, or flulike symptoms, but when the organism reaches the brain, it begins to turn the delicate networks into Swiss cheese. At its worst, the disease causes blindness, mental retardation, and even death. The prompt response of the medical and public health authorities in Canada minimized the impact of the outbreak, but not before the disease struck more than one hundred people. Toxoplasma, the single-cell protozoa responsible, forms a chlorine-resistant oocyst similar to cryptosporidium.
Cities with tightly controlled, “protected” watersheds for their source water are in many ways far ahead of cities that depend on multiple-use lakes and rivers for their source water, but watershed protection alone cannot guarantee safe water. Water treatment offers an extra measure of safety for cities with protected watersheds. For cities with unprotected watersheds, purification is the primary line of defense against disaster. In other words, no city can rely on untreated drinking water. So for any water supply the critical question is, how much treatment is enough?
The reduction in allowed turbidity levels and the plans to test for cryptosporidium oocysts in some water supplies specified in the EPA’s 2005 rules for surface water treatment helped plug some of the gaps that allowed billions of oocysts into Milwaukee’s drinking water. In the name of economic efficiency, however, these rules avoided any call for a sweeping renovation of America’s treatment plants. Only the most decrepit or inadequate plants will see significant new construction. There was no call for a significant change in the underlying method for water purification. Instead most of the improvement came from optimizing the operation of the existing plants. Optimizing treatment plant operation is laudable, but why must it take a disaster to convince treatment plant operators to run their plants efficiently?
The 2005 rule changes will certainly reduce the risk of waterborne disease in the United States, but the new EPA standards do not mandate water that is dramatically cleaner than the water that flowed out of the Howard Avenue Treatment Plant in Milwaukee during the spring of 1993 and caused the massive outbreak of cryptosporidiosis. Utilities that merely toe the line drawn by these rules may not be fully protecting their community.
In fact, some utilities are using self-imposed standards that are far stricter than those issued by the EPA. Milwaukee, for example, now seeks to maintain water with one-tenth the level of turbidity allowed by the EPA. One recent study suggests that these standards may provide an adequate measure of safety.
A research team from the University of California at Berkeley, the CDC, the AWWA, and the EPA recently completed a study in Iowa that involved placing filters in homes served by a utility treating water from the Mississippi River. When the investigators compared rates of disease in homes with filters to a group of similar homes without filters, they found no difference in disease rates.
The study replicates an earlier study in Quebec that attributed 35 percent of cases of gastrointestinal illness to drinking water, but it differs in two important ways. First, unlike the Canadian study, participants in the Iowa study did not know if their water was filtered or not. This was intended to eliminate any error related to those without filters simply reporting more illnesses. Second, the management of the water utility in Iowa was aware the study was under way. If a similar study had been undertaken in Milwaukee during the spring of 1993, perhaps the elevations in turbidity would have been met with greater urgency. Perhaps the outbreak of cryptosporidiosis would never have happened.
Nonetheless, the Iowa study suggests that it may be possible to
minimize or even eliminate waterborne transmission of existing pathogens using the best available conventional drinking water treatment operating at maximum efficiency. But generalizing based on the experiences of a single plant over a limited period requires caution. For example, a major flood occurred during the course of the study and its impact on exposure to pathogens may have dwarfed the effects of drinking water. More important, the water produced by the treatment plant in the Iowa study had an average turbidity more than 85 percent below the maximum average turbidity allowed by the EPA’s new, stricter rules.
Few treatment plant operators run their plants under the intense scrutiny of federal researchers. As time goes on and the public spotlight disappears, one has to worry that vigilance will fade and water that just meets the standards will become acceptable again. The misadventures of the Koebel brothers should remind us that looking at one exemplary facility is not likely to give us a full picture of the future safety of drinking water in the United States.
The future quality of our water supply depends heavily on our vision for that future. For reasons of cost control, the EPA regulators settled on a scenario that relies on conventional treatment technology. Some utilities have moved beyond simple optimization to offer a far bolder vision for the future of water.
One such alternative sits on a bluff above the Mississippi River in Columbia Heights, Minnesota. There, on September 1, 2005, water began to flow into one of the most advanced water treatment systems in the world and out to the people of Minneapolis. Each day that plant squeezes 70 million gallons of water into 43 million tiny hollow fibers and out through holes two hundred times smaller than a cryptosporidium oocyst.