Toledo, Ohio shut off drinking water service to 500,000 people because of the presence of microcystin, a powerful neurotoxin excreted by blue-green algae, also known as cyanobacteria. Once again cyanobacteria have taken over much of Western Lake Erie, the source of the city’s drinking water, which could be a recurring problem exacerbated by climate change. The cyanobacteria are a troubling indicator of a variety of problems now manifesting themselves in Lake Erie and also in other parts of the country that stem from the relationship between climate change and water quality.
Toledo is no stranger to the problems caused by cyanobacteria blooms. In 2011, more than 1,600 square miles of the lake were covered with the green slimy blooms, extending from Toledo in the West all the way up the southern shoreline as far as Cleveland. Each summer now, Lake Erie experiences blooms that close beaches, foul fishing areas, and disrupt recreation throughout the summer. The outbreak of microcystin that began last Thursday has not just disrupted people’s enjoyment of their boats and beaches, it’s caused the city’s drinking water system to be shut down.
The problem stems from two major factors. The first is that there is too much phosphorus in the water, a fertilizer that feeds these kinds of toxic algal blooms. The second is warmer air and water temperatures, a trend attributable to a warming climate.
Blue-green algae thrive in warm waters when there are high levels of phosphorus to feed upon. On Lake Erie large amounts of phosphorus are released from farm runoff and sewage treatment plants like those in Detroit, Toledo, and Cleveland. And because Lake Erie is so shallow it warms up quickly – and getting warmer thanks to climate change – making it an ideal cauldron for cyanobacteria blooms.
The events playing out in Toledo are a dramatic and highly visible example of how climate change is affecting our nation’s water resources, but it is hardly the only example. More troubling, these events foreshadow what the new normal is likely to be throughout the country.
When we think about the impacts of climate change, people often think of sea level rise and the rising potential for heat waves. But the impacts to water quality, water levels in lakes and streams, and water infrastructure are equally daunting.
On two of the other Great Lakes, Michigan and Huron, water levels have been steadily dropping for a few years. In early 2013, lake levels reached record lows. Warmer temperatures have resulted in higher rates of evaporation and dropping lake levels. Warmer winter temperatures have been particularly problematic, because warmer winters mean far less ice cover on the Great Lakes, leading to much more evaporative losses in the winter, kind of like removing the lid from a bowl of water. Longterm, the amount of water in the lakes may be decreasing, causing problems for drinking water supplies as well as shipping in the area (as lake levels drop, cargo ships have less draft and have to carry less). In Chicago, low lake levels lead to a perverse problem when increasingly frequent extreme rainfall events strike. Massive quantities of polluted runoff go into the Chicago River causing the river to reverse and flow into Lake Michigan. Extreme precipitation that arises from the changing climate also contributes to increased risk of local flooding and more polluted runoff in communities.
Other communities outside the Great Lakes also are dealing with problems related to water quality and climate change. The Mississippi River basin is a region that struggles with nutrient pollution problems that climate change will likely exacerbate. The Gulf Hypoxic Zone, or Dead Zone as it’s often called, is a huge area off the coast of Louisiana where oxygen levels have dropped to the point where marine life cannot survive. The culprits are excessive quantities of nitrogen and phosphorus from the Mississippi River that feed algal blooms of such a magnitude that they suck up most of the oxygen out of the water. As temperatures rise in the Gulf, these algae blooms may grow larger or persist for longer, if we do not limit the flow of nutrient pollution.
The problems of the Gulf are also felt by the communities along the Mississippi River and its tributaries. According to state water quality reports, Illinois has 3,400 miles of streams and over 100,000 acres of lakes impaired by nutrients or low dissolved oxygen. Missouri has over 900 miles of streams and 100,000 acres of lakes similarly impaired. Iowa does not even assess the impacts of nutrients on its waters, citing the lack of water quality standards as justification. These pollutants are clearly a major water quality problem throughout the Upper Mississippi River Basin, which in turn are major contributors to Gulf Hypoxia. As temperatures warm due to climate change, communities throughout the basin may start to experience problems related to algae blooms, perhaps including blooms of toxic cyanobacteria that have caused Toledo to shut down its drinking water system.
The intersection of climate change and water is becoming increasingly problematic. Events in Toledo this week illustrate that the problems have multiple interconnected causes. But Toledo is not alone in dealing with the interconnected problems of climate change and water. And it will be among a growing number of communities dealing with similar problems, if we don’t start looking ahead and recognizing the challenges we need to deal with.
The solutions are not pie-in-the-sky. They’re largely common sense.
First, we need to recognize the long-term risks that climate change poses to our water resources. Our water infrastructure needs to be designed to handle a new range of water quality and water quantity problems that were not envisioned when they were first built. States like Illinois are starting to encourage communities to anticipate these issues.
Second, we need to take action to reduce nutrient pollution. My colleagues, Karen Hobbs and Anne Alexander, have posted on the actions USEPA and states need to take to reduce nitrogen and phosphorus pollution including adoption of the Clean Water Protection Rule and water quality criteria for nutrients.
And finally, we need to reduce the pollution that causes climate change.
For more information
Toledo Blade's Coverage of Algae Bloom — up to date stories on what's happened and happening in Toledo
NOAA’s Lake Erie Harmful Algal Bloom Bulletin — includes current extent of cyanobacteria blooms and projections for next few days
Cyanobacteria and Cyanotoxins: Information for Drinking Water Systems — EPA fact sheet on the causes of cyanobacteria outbreaks, the different types of toxins they produce, and the effectiveness of different treatment technologies for removing these toxins from drinking water
National Climate Assessment: Midwest Impacts — present and future effects of climate change are discussed in detail