As the nation's utilities scramble to complete federally mandated vulnerability assessments to water and wastewater plants and utilities, system operators are also eagerly boning up on new high-tech tools designed for early detection of even minute changes in water quality.

At the American Water Works Association's 121st annual conference and exhibition, held in New Orleans June 16-20, security-based sessions drew standing-room-only crowds. Before the opening session, a day-long workshop on counter-terrorism and security for water treatment plants was oversubscribed. "They had 92 registrants and well over 100 showed up. They ran out of workbooks," said Paul Blair, a Livingston, N.J.-based engineer with AECOM's Metcalf & Eddy subsidiary.

The next day, water professionals packed another session on technological advances in drinking water technology to hear about how U.S. water providers are strengthening security and about the tools they are using. Immediately after last Sept. 11's attacks, the Metropolitan Water District of Southern California earmarked $5.5 million for heightened security, said Yong H. Kim, an engineer with Palm Desert, Calif.-based USFilter. "Two-thirds of it is for physical security improvements, but $1.2 million is for improved analysis and monitoring," he said.

Early and accurate detection of contaminants in water is essential, Kim said, especially at three key points of vulnerability identified by the U.S. Environmental Protection Agency: raw water intakes, finished water reservoirs and within the distribution network. While there is no single tool to measure all pollution, "the more parameters [that are] monitored, the better chance we have to detect problems," Kim said. Online monitors can now measure minute changes in pH, conductivity, dissolved oxygen and other upset conditions¯early indicators that something is wrong with the water supply.

New analytical tools are changing the standard monitoring practices, Kim said. A potentiostatic measurement device uses three electrodes to measure chlorine residuals, eliminating chemical reagents. And particle counters are more sensitive water quality indicators than turbidity monitors.

The Central Utah Water Conservancy District was working on water security before 9-11, for the 2002 Winter Olympics. "Over half the state gets water through our system, said Gerard Yates, treatment operations manager. Rainfall averages only 13 in. a year in rainfall, so the water wholesaler collects water from snowpack in a series of Wasatch Mountain lakes, then transports it through a stream, river and pipe network to an 80-million-gal-per-day treatment plant.

After a tractor trailer transporting liquid ammonium nitrate fell into the river upstream from the plant in 1992, the district began developing an online early warning system. "We used an AWWA Research Foundation grant to look worldwide for the most cost-effective, best available technologies," said Yates. The district added monitors at the plant and upstream to measure temperature, pH and total dissolved solids every 30 minutes.

A German-made toximeter monitors raw water by measuring its effect on daphinae¯a microscopic water flea. If the fleas die, or even swim in an unusual manner, the device triggers an alarm to alert the plant operator that something has changed within the raw water supply. "We learned a lot about daphinae," said Yates. "We change them every week. They're very sensitive. Chlorine kills them." The toximeter cost $43,000, he said. Another tool, an oil and grease spill monitor, shines a laser on the water surface to detect changes in reflectance.

The utility also installed security cameras and worked closely with local law enforcement and regulatory agencies to develop a spill response plan.

Vendors expect established technology-based tools, such as surveillance cameras and geographic information systems, to become commonplace in water treatment systems as they add features and drop in price. And no matter what tools or security measures are put in place, there is no substitute for common sense. Disgruntled employees are a far bigger threat than terrorists, says Ron Booth, a security consultant in the Atlanta office of CH2M Hill Cos. "The best way to avoid problems there is simple¯treat your people well," he said.

David W. Coppes, a water supply group operations manager with the Massachusetts Water Resources Authority. "You have to balance security improvements with operator inconvenience. If the operator is going to prop the door open, because you've designed a system that causes him to do that, you haven't really made the place more secure."