CLEVELAND _ Since moving to the Cleveland area seven years ago, Malina Cano Rauschenfels has become accustomed to discolored water flowing from her faucet, although she has never fully understood the reason behind the yellow or brownish tinge.
Cano Rauschenfels, 41, who tutors schoolchildren in music from her Cleveland Heights home, occasionally sees the city of Cleveland's Division of Water notifications advising residents to avoid washing laundry because the sullied tap water may stain clothes _ but that the water is still safe to drink. After cleaning brown sludge from her water filtration system, Cano Rauschenfels remains skeptical.
"I would be terrified to give my kids this water," she said. "Don't wash your clothes or do laundry, but drinking it is fine? What are the effects of that?"
For the past two decades, these outbreaks of tainted tap water have occurred periodically in late summer. They have stained plumbing fixtures, ruined loads of laundry, and produced odd smells and a metallic taste.
By all accounts, it has been a nuisance to many customers of Cleveland's water department, the nation's 10th largest water system that serves 1.4 million people. But it may be representative of a more serious issue tied to Lake Erie's "dead zone," a sprawling layer of deep water with so little oxygen that many fish can't survive.
As agricultural runoff and urban wastewater pour into Lake Erie, the nutrients and warmth of the shallowest Great Lake give rise to massive blooms of algae and bacteria. This plethora of microbes in Erie alone outnumbers the stars in the universe, according to scientists.
Each summer, when legions of algae and bacteria die, they precipitously fall to the lake bottom, and their microscopic corpses rot en masse. In the deeper waters of Lake Erie's central basin, the process of decomposition depletes the oxygen in the bottom waters.
When this oxygen-deficient water interacts with Erie's lakebed sediments and clay, heavy metals such as manganese and iron are released from the muck into the water. In particular, manganese not only causes discoloration but also has been linked to permanent neurological issues. Low-oxygen conditions also contribute to more caustic water that can slowly corrode lead and copper service lines over time and raise the potential for exposure to those metals.
Meanwhile, in the lake, once oxygen levels drop below a certain threshold, coldwater fish and bottom-dwelling aquatic organisms suffocate or are forced to migrate, turning much of the central basin's bottom waters into a dead zone.
Between the 1960s and the 2000s, the number of dead zones worldwide has doubled every decade as a result of human activities and a warming atmosphere.
Globally, scientists have identified more than 400 dead zones in ocean waters including the Gulf of Mexico, Long Island Sound and Chesapeake Bay. But freshwater dead zones, which scientists are learning may pose a risk to drinking water, exist throughout the Great Lakes, including Lake Michigan's Green Bay, Lake Huron's Saginaw Bay, Lake Ontario's Hamilton Harbour and Lake Erie's central basin.
Federal studies on climate change show the Midwest is experiencing heavier rainfall. This precipitation has swept more waste into coastal areas, a trend that has promoted larger algae blooms and oxygen deprivation. With a warming climate, dead zones are persisting longer, prolonging stifling ecological conditions and raising the probability for fouled water to wash into coastal drinking water intakes.
Just over a decade ago, levels of heavy metals in raw Lake Erie water climbed to problematic levels. Scientists and water treatment officials only then learned about the dead zone's potential effect on coastal drinking water and are still trying to understand how serious of a health risk it could be.
"It's mostly a nuisance, but it can be a health concern," said Ed Verhamme, a coastal engineer at LimnoTech, an environmental consulting firm that helps Cleveland track the dead zone.
Alex Margevicius, commissioner of the Cleveland's Division of Water, said treating water is now more complex.
"Here, in Cleveland, and in a lot of places in the Great Lakes, we worried about treatment and distribution: treating the water and sending it where it needed to go," he said. "Source, we didn't think about it for decades and decades. In the last 15, 20 years that has dramatically changed. We have focused on what goes on in the lake. What surprised me, as much as anything, is how complex Lake Erie is as an ecosystem; the biology, chemistry, the physics of what goes on is incredibly complicated."
