The mayor of Toledo, Ohio, this morning lifted the drinking water ban that forced the city's 500,000 residents to turn off their taps for more than 48 hours, but the incident was not the first time a harmful algae bloom has fouled drinking water supplies -- and experts say it will not be the last.
Since the 1990s, blue-green algae blooms have been an annual occurrence in Lake Erie. Those blooms contain bacteria that can produce cyanotoxins, in this case microcystin, which can cause vomiting, diarrhea or harm to the liver.
The weekly algae update released by the National Oceanic and Atmospheric Administration on Friday showed a cluster of cyanobacteria in the western corner of Lake Erie, including the stretch near Toledo's drinking water intake. After tests found unsafe levels of the toxin in Toledo's drinking water, the city instituted a ban that sent residents in search of bottled water.
Go-to water treatments like chlorination and boiling don't work on cyanotoxins because they serve only to concentrate them. By the time the toxins have been detected in a water supply, it's often too late.
"That's the real bugaboo," said Brent Fewell, partner at the law firm Troutman Sanders LLP and former principal deputy assistant administrator for U.S. EPA's Office of Water. "I will tell you that by the time you're detecting microcystin at elevated levels, it's frankly too late and you have to just wait it out."
Algae blooms are an increasing problem across the country, driven by excess nutrients washing off farm fields and suburban lawns. But the situation in Lake Erie, the shallowest of the Great Lakes, is particularly stark.
The region also has an added problem: invasive zebra mussels that filter the water, allowing sunlight to penetrate deeper and increase the water's temperature.
"Because zebra mussels are excellent filters, they are filtering out a lot of other types of phytoplankton and other things that are in the water, so the water clarity is greater," said Sonia Joseph-Joshi, program manager for NOAA's Center of Excellence for Great Lakes and Human Health. She also noted that recent research indicates that the mussels selectively feed on native algae that might otherwise outcompete the harmful algae.
Because of Lake Erie's particular vulnerability to harmful algal blooms, Ohio has taken a proactive approach to monitoring and planning for them. The state's Environmental Protection Agency works with public water systems through a tiered system to monitor source water for algae blooms and test both raw and treated water for cyanobacteria, an agency spokeswoman said.
Despite the prevalence of algae blooms across the country, U.S. EPA currently does not regulate the toxins. The agency has in the past listed algae-linked toxins on a candidate list of contaminants that the agency is considering regulating, but it has not opted to move forward with a rulemaking on them.
Fewell said the agency thought it did not have enough information about the prevalence of the toxins and utilities' capabilities to monitor for them to warrant regulation. But, he argued, that may soon change.
"These types of great outbreaks are going to force EPA and the states to look much harder at regulation," he said.
Keith Cartnick, senior director for water quality and compliance at United Water, a water services company, said industry is indeed asking for more regulation. He serves on an advisory group for the American Water Works Association that has asked for cyanotoxins to be added to the next EPA contaminant list.
"Some states have really thorough programs," he said. "Ohio is one, actually, and Oregon and Washington have very, very thorough programs that basically cause a reaction like what we're seeing right now. But then there's other states where there's nothing."
Cartnick, who dealt with the algal bloom problems in a water reservoir United Water manages in Lambertville, N.J., has been working on proactive management strategies for water utilities.
Because increased treatment can be expensive, many experts are looking at the broader watershed for ways of reducing nutrient runoff. In New Jersey, for example, the state banned phosphorus in fertilizers.
Ohio, which also contributes to the massive Gulf of Mexico dead zone each year through runoff into tributaries of the Mississippi River, has been home to a number of innovative approaches to nutrient reduction, including water quality trading (Greenwire, March 10).
While drinking water is regulated under the federal Safe Drinking Water Act, the types of activities that affect water quality before it gets to a community's intake are regulated under a different statute, the Clean Water Act. The divide has led to a siloing among people working on water issues.
Ultimately, Fewell said, he hopes incidents like the one in Toledo will lead to better integration.
"Right now, cyanobacteria are not regulated under the Safe Drinking Water Act, but it's very clear the link between water quality and drinking water where reservoirs depend up on clean, safe sources of water," he said.