Tom Arrandale is a GOVERNING correspondent.E-mail: firstname.lastname@example.org
More than a decade ago, Minneapolis officials realized that it was time to replace the city's 80-year-old water treatment plant, which purified drinking water drawn from the Mississippi River. But their task got more complicated, and a lot more costly, after 403,000 Milwaukee residents got sick and 104 died in 1993 when microscopic Cryptosporidium parasites infiltrated that Wisconsin city's tap water.
Last fall, 12 years after Milwaukee's misfortune, Minneapolis Water Works finally opened the valves on a $65 million filtration plant. When in full operation, the facility will run up to 70 million gallons a day through several dozen 28-foot-long filtration units containing synthetic membranes with pores so small they can screen Cryptosporidium and other minute organisms from the water piped to homes and businesses.
Minneapolis' new Columbia Heights plant is the largest in North America to use "ultrafiltration" polymer membranes invented to clarify water for making beer and fruit juices and cleaning electronic manufacturing components. Minneapolis officials say the city hasn't suffered an outbreak of waterborne disease since typhoid and cholera epidemics in the early 1900s. But Crypto protozoa have been detected in the Mississippi upstream from Minneapolis, possibly from springtime farm runoff or sewage treatment effluent.
The city's approach demonstrates how local water systems may have to gamble on high-tech investments to keep up with new federal drinking water standards and assure citizens their water will stay safe to drink. In designing the Columbia Heights treatment plant, "our goal was to try to anticipate the new regulations we knew would be coming," says Dale Folen, the project manager.
Across the country, water utilities are confronting similarly expensive choices. A 2005 survey of nearly 400 cities by the U.S. Conference of Mayors' Urban Water Council found that roughly 60 percent of the biggest cities either had made major water treatment upgrades since 2000 or are planning investments over the rest of the decade. The U.S. Environmental Protection Agency predicts that local governments must spend more than $500 billion by 2019 to bring sewage and drinking water systems up to existing federal standards. Moreover, in settling lawsuits by the Natural Resources Defense Council and other environmental groups, EPA last December agreed to forge ahead with regulations that will force water utilities around the country to significantly upgrade how they go about treating drinking water supplies.
Some of the country's biggest cities--even those blessed with pure, safely guarded water supplies--could be forced to follow Minneapolis' lead and make massive investments in state-of-the-art treatment facilities. Once the new rules go fully into effect, it will no longer be sufficient for utilities to safeguard water at its sources, run it through simple sand filters and dose it with bacteria-killing chlorine. One pending rule for the first time will require cities that pump drinking water from underground aquifers to begin testing and treating the groundwater before it's piped to homes and businesses. Another adopted in January sets limits on chemical byproducts left in household water after it's purified with chlorine, forcing utilities to consider alternative disinfection processes. A third new regulation tightens monitoring and treatment rules for 14,000 systems supplying 180 million people who drink water from surface lakes, streams or open reservoirs where Cryptosporidium, Giardia and other pathogens are likely to show up.
Crypto reproduces in the intestines of mammals, including humans, and can be washed into water bodies along with fecal matter from sewage, animal feedlots and farmlands. Chlorine disinfection doesn't faze the organism, and it's too minuscule for conventional sand filtration systems to trap. EPA's newly strengthened surface water rule directs municipal agencies to monitor water supplies for Crypto over a two- year period. Depending on how much they find, even systems that already filter their water must improve treatment technology to remove up to 99 percent. A few cities draw water from protected watersheds and don't run it through filters. Under EPA's rule, however, they'll be required to build sophisticated filtration plants, install ultraviolet lighting or treat water with ozone to kill or disable at least 99 percent of Crypto in their supplies. Systems also must install covers to keep the organisms out of reservoirs where water is stored after it's treated--or disinfect it again before piping it to homes and businesses.
Costs will vary from place to place, and utilities must weigh whether ozone treatment, UV technology or several membrane systems will make the most financial sense. The simplest option treats water with ozone, a derivative of oxygen that's more effective than chlorine in rendering Cryptosporidium harmless; but it still costs four times more than conventional disinfection, according to the American Water Works Association. Before building its new "ultrafiltration" plant, Minneapolis ruled out even tighter "nanofiltration" membranes or a reverse osmosis system. Those processes produce water that's even purer, but they pump water at such high pressures that energy costs would be prohibitive. By EPA's estimates, complying with the Crypto rule will cost the country's public water agencies as much as $133 million a year, or $2.59 annually for every household. Municipal agencies that draw from relatively pristine water resources where Crypto has never shown up complain that it makes no sense to force their ratepayers to bear that fiscal burden.
Portland, Oregon, for instance, is challenging the EPA rule in court. Portland is one of six major cities--along with Boston, New York City, San Francisco, Seattle and Tacoma, Washington--that currently don't need to filter the water they take from well-protected supplies. Portland draws most of its supply from the Bull Run River watershed, a 100-square-mile tract that Congress set aside in 1895 in the Douglas fir timber of Mount Hood National Forest. Federal and city rules exclude logging and livestock grazing, and the reserve is even off limits to hunters, fishermen, hikers and skiers. As things stand, "the risk of our water being contaminated by Cryptosporidium is next to nil," says David G. Shaff, the Portland Water Bureau director. EPA's rule, he adds, will force the city "to spend hundreds of millions of dollars for no measurable improvement in public safety and health."
Portland officials like to brag about the city's ample supplies of high-quality water, and business leaders fear that complying with EPA's mandate will jeopardize what's now an economic advantage. Three years ago, major industries in Oregon mounted a campaign with local trade associations that persuaded the city council to back away from a tentative plan to build a membrane filtration plant that could cost up to $200 million. The Portland Water Users Coalition contended that investing so much in what they saw as unproven technology could raise water rates 30 percent. Portland officials also balked at installing expensive covers atop two reservoirs when residents objected they would turn pleasant in-town lakes into eyesores.
Shaff says Portland hopes the other five big cities that don't currently filter water will join the legal challenge. But depending on the outcome of Crypto monitoring, communities that draw drinking water from heavily used rivers and lakes supplies will be forced to pick from a "microbial toolbox" of treatment alternatives that EPA is putting together. In December, Newport News, Virginia, opened a $73 million ozone treatment plant that EPA Assistant Administrator Benjamin Grumbles praised as "a shining example of getting ahead of the regulatory curve."
Minneapolis considered ozone treatment that inactivates Crypto as a cheaper alternative. But city officials concluded that running water through membranes that completely remove Crypto organisms, along with even smaller viruses and bacteria as well, would give customers more confidence that it's safe for drinking, says Water Works Director Shahin Rezania. Six months after test runs began, the designers were still working on computer software glitches and other technical problems they're required to solve before city workers take over the plant's intricate machinery. The membranes are performing as expected, but operating the highly automated system "is quite different from running a traditional sand filter," Rezania says.
So the city is still relying on the 1913 treatment plant until its replacement is ready for full operation. Even with an old-fashioned treatment system, Minneapolis has never detected Crypto in finished city water. No large municipal system has suffered a major incident since Milwaukee's deadly 1993 outbreak. It's still a mystery how Crypto got into Milwaukee's water, but the city has been on guard ever since. Milwaukee Water Works has been testing at its Lake Michigan intakes every two weeks for the past 13 years, and it's spent $100 million to rebuild a filter system, install ozone treatment and revise filter-cleansing practices. "We are so in compliance" with EPA's new regulations, says Carrie Lewis, the Milwaukee drinking water superintendent. "Nobody knew there was a risk until the 1993 outbreak, and that changed everything about how water treatment professionals look at what they do."
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