Great Lakes Drinking Water Fouled by Toxic Algae
Years of inaction make green blooms the most unhealthy, unsightly, and urgent water quality problem in the world’s largest source of fresh surface water
By Codi Yeager-Kozacek
Circle of Blue
By Codi Yeager-Kozacek
Circle of Blue
OAK HARBOR, OH — On September 4, 2013, Henry Biggert, the superintendent of the Carroll Water and Sewer District, near Toledo, Ohio, got the first clue that he could have a public health crisis on his hands. An analysis of water samples taken from Lake Erie, the district’s only water source, showed that levels of a toxin released by algal blooms had spiked.
In five years of voluntarily testing for the toxin, Biggert and his staff had never seen anything like it. So they followed protocol and retested the water early the next morning. Unable to process the sample at their own facility, they sent it to another plant nearby and waited.
At 3 p.m. Biggert received the second set of results. They were alarming. Toxin levels in Lake Erie were greater than 50 parts per billion. Levels of the toxin in Carroll Township’s treated drinking water were 3.8 parts per billion—nearly four times the safety limit recommended by the World Health Organization.
Within two hours, Biggert decided to act. He shut down the Carroll Township treatment plant and simultaneously alerted the community’s 2,000 residents not to drink the water. If they did, they might get very sick—become nauseous, vomit, and suffer liver damage.
“I had major concerns with [the decision], but I really didn’t feel I had a choice,” Biggert told Circle of Blue, describing how he and his staff rushed to get the word out to area residents, notifying TV stations in Toledo as well as local newspapers and radio stations. They activated Ottawa County’s reverse emergency system, calling all the households that signed up to be warned of public dangers.
Biggert also opened an emergency connection with the Ottawa County Regional Water Plant, which began pumping safe water to residents that evening. Biggert and his staff stayed at the Carroll water plant until midnight, flushing the system, and returned at 4 a.m. the next day to test for the toxin.
“We didn’t really know what we were dealing with,” Biggert said. “We wanted to be very safe and conservative.”
“It was a crazy day, it was a crazy week,” he added. “But no one got hurt, so I guess it was all worth it.”
The September incident put Carroll Township in the unenviable position of being the first Great Lakes community to directly contend with the health risks associated with algae. Algal blooms are now ubiquitous in lakes and oceans around the world, risking human health, and sucking up so much oxygen they suffocate fish and invertebrates. Dangerous blooms have been documented from the Gulf of Mexico to the Baltic Sea.
The cause: industrial and agricultural practices — driven by demand for ever more food, energy and consumer products — that dump nutrients into the water.
Massive green outbreaks of toxic algae have emerged in recent years as the source of the most unhealthy, unsightly, and urgent water quality problem in the five Great Lakes that form the largest system of fresh water in the world.
“It’s a highly complex system that is stuck in the middle of an industrial heartland, where you also have some of the breadbasket of the nation,” said Andy Buchsbaum, regional executive director of the National Wildlife Federation’s Great Lakes Regional Center in Ann Arbor, Mich. “So you’ve got this incredible mix of stresses, and at the same time you’ve got a very complex system that’s so large that it generally handles it pretty well—until it doesn’t.”
Forty-five years ago Lake Erie was declared dead. Forty-four years ago the Cuyahoga River in Cleveland caught fire. Forty-two years ago the United States passed the Clean Water Act, which among other environmental achievements brought Lake Erie back to robust health, and ensured that no river in the United States ever caught fire again.
But the lakes aren’t as clean as they could or should be. The problem isn’t that the 1972 federal Clean Water Act hasn’t been effective. The problem is that the law’s Congressional authors, as the result of political influence overwhelming ecological science, deliberately removed from federal and state oversight a big portion of known water pollutants.
“If you ask why didn’t the Clean Water Act and the other stuff we did back in the 70’s and 80’s work?” Buchsbaum said. “Well it did for the narrow range of things that it was designed to address. But that narrow range doesn’t come close to tackling all of the complex stresses in this incredibly complex system.”
Case in point: Algae is overtaking Lake Erie. In 2011, the largest harmful algal bloom ever recorded on the lake could be seen from space in swirls of iridescent green unfurling from the coastlines and into the blackness of open water. The bloom stretched from Toledo to Cleveland and beyond. From shore, it appeared as milky green goop that turned the water opaque. It was three times the intensity of the previous record bloom — which occurred in 2008 — and stretched across 5,000 square kilometers (1,930 square miles) at its peak.
Consisting primarily of microscopic cyanobacteria called Microcystis, the blooms in Lake Erie release a potent toxin when they die. The toxin, which causes skin rashes and burns, also can result in nausea, vomiting and liver damage if ingested, and may be a carcinogen. It has been known to kill dogs and livestock. No human deaths have been recorded in North America, but cyanobacterial toxins killed 76 people at a dialysis center in Brazil in 1996. The toxin can persist even after boiling, which concentrates it.
In addition to human health concerns, the algal blooms can create various concerns for aquatic health. In Lake Erie, algal blooms decrease the acidity of the lake water, which can irritate fish gills. They can also starve tiny organisms at the bottom of the food chain, according to Justin Chaffin, a senior researcher at Ohio State University’s Stone Laboratory in Put-in-Bay, Ohio.
“Cyanobacteria are poor food for zooplankton — small creatures that are food for smaller fish. Generally during a cyanobacterial bloom the zooplankton run out of food and die,” Chaffin told Circle of Blue.
Most worrisome is the oxygen deprived “dead zone” caused by algal blooms. During the summer, the water in lakes naturally separates into three distinct temperature zones. The coldest, densest water, called the hypolimnion, sinks to the bottom while the warmest water, called the epilimnion, sits on top. In between is the thermocline, where the temperature changes rapidly. The oxygen in the deep hypolimnion has to last all season, until cold weather allows the lake to mix again.
When algal blooms sink to the bottom and die, the decomposition process uses up so much oxygen that nothing else can live in the hypolimnion, creating a dead zone. In Lake Erie, the hypoxic dead zone is typically found in the lake’s central basin.
“Critters that live on the bottom can’t survive unless they are specialized for living in very low oxygen conditions,” Peter Richards, a senior researcher at Heidelberg University’s National Center for Water Quality Research in Tiffin, Ohio, told Circle of Blue. “Fish have to get up and go somewhere else. For example, there are certain kinds of fish in Lake Erie that like cold water conditions. They’re pushed up at least into the thermocline, where their metabolism is faster because it is warmer. They are separated from their preferred food supplies, so it slows down their growth, and it concentrates them in places where larger fish can more easily find them and eat them. So it has a real impact on the way the ecosystem functions.”
Richards pointed out that Lake Erie has likely always had a seasonal dead zone to some extent. But it has grown bigger in recent years, a trend consistent with larger algal blooms.
Harmful algal blooms have also been observed in Saginaw Bay in Lake Huron, and are a persistent problem in Lake Michigan’s Green Bay, where they fuel a dead zone much like the one in Lake Erie.
In addition, mats of bottom-dwelling green algae called Cladophora are washing up on Lake Michigan beaches in prime tourism regions, such as Wisconsin’s Door County and Michigan’s Sleeping Bear Dunes National Lakeshore. Cladophora is not toxic, but it is unsightly and smells as it decomposes.
“This year, my hand is still sore from forking out Cladophora from behind my pier,” Peter Sigmann, who lives on Little Sturgeon Bay in Door County, told Circle of Blue. “It was hundreds of pounds of wet stuff.”
Sigmann is a member of the Door Property Owners, a nonprofit organization representing the interests of permanent and part-time residents of Door County. The group worries that the value of properties along the lakeshore will decline if the algae problem is not addressed. Some members report that visitors refuse to stay in their vacation rentals because of the algae.
The source of the damaging blooms is phosphorus. Phosphorus makes plants grow. When too much of it gets into a watershed, algae thrive. That formula is basic water chemistry that scientists have known for over a century. What’s new is that the type of phosphorus entering the Great Lakes is changing, according to scientists at Heidelberg University, who have been monitoring water quality in the Lake Erie watershed for more than 40 years.
The total amount of phosphorus leaving a watershed and entering Lake Erie is calculated as the sum of two different forms of the nutrient — dissolved reactive phosphorus (DRP) and particulate phosphorus. Data collected by Heidelberg researchers show that, since the mid-1990s, levels of DRP have been on an upward trend. For example, dissolved reactive phosphorous released into Ohio’s Maumee River in April and June, a critical time for spurring algal blooms in the summer, has increased from approximately 100 metric tons in the mid-1990s to 150 metric tons by the end of the past decade. Amounts of particulate phosphorus entering the Maumee watershed have declined from approximately 600 metric tons to 550 metric tons over the same time period.
Despite its relatively small proportion of total phosphorus, scientists believe DRP is a primary driver behind the resurgence of algal blooms in Lake Erie. That’s because it is soluble in water and 100 percent of it is available to sustain algal growth and reproduction. In contrast, only 30 percent of particulate phosphorus—which is chemically bound to sediments—is available for algae to use. Furthermore, particulate phosphorus is attached to suspended sediments that settle to the bottom of bays and lakes, making it even less available to algae, while DRP remains dispersed within the water where algae can access it.
Though levels of DRP are highly variable from year to year depending on the amount of rainfall washing the phosphorus into the water, growing amounts of DRP appear to correlate closely with Lake Erie’s intensifying algal blooms. In 2011, record amounts of DRP washed down the Maumee and Sandusky rivers — 267 metric tons and 63 metric tons, respectively — during spring storms. That summer and fall, the largest harmful algal bloom ever recorded on Lake Erie stretched 193 kilometers (120 miles) from Toledo to Cleveland, and beyond. The next year, when DRP flowing down the Maumee River was only 15 percent of 2011 levels, the offshore bloom didn’t even reach Sandusky.
The surge in DRP is likely the result of advancing agricultural practices, say the researchers at Heidelberg. Part of the increase may even be an unintended result of erosion control practices implemented in the 1980s and 90s to reduce particulate phosphorus.
“One of the things we observed is, holy cow, the same watersheds where we’ve been applying—where farmers have indeed adopted quite a few [best management] practices—have gotten worse in terms of dissolved phosphorous,” said David Baker, the founder and director emeritus of Heidelberg’s National Center for Water Quality Research. “They’re getting better in terms of particulate phosphorus, but of all the watersheds we look at, virtually all the agricultural watersheds are showing increases in dissolved phosphorus going into the lake.”
Larger farms, larger equipment, changing tillage practices and different fertilizer application processes could all be behind the shift. But it is hard to link practices implemented on the field directly to phosphorus levels measured in a stream.
As part of the Choke Point: Index project Circle of Blue researchers analyzed data for land use and crop production trends in Ohio and found that soybeans are now much more commonly planted in the state’s fields than corn, a potential factor in why phosphorous, a soybean nutrient, is leading to massive algae blooms in Lake Erie.
The link is complex and theoretical. The amount of phosphate applied to crops varies greatly depending on where they are grown. What’s more, soybeans receive lower phosphate applications than corn crops. Soybeans, though, are more often grown in so-called “no-till” fields that aren’t plowed or rigorously cultivated.
Researchers at Heidelberg University assert that no-till planting practices may lead to greater runoff of dissolved reactive phosphorus because the phosphate fertilizer gets concentrated in the top inch of soil rather than mixed down into the ground. But the researchers caution that they have not subjected the theory to intense scientific study.
What Heidelberg scientists have done to get a better idea of the interaction between fertilizer applications and algal blooms is to develop a watershed model that can predict how cultivation choices affect downstream concentrations of phosphorus. The model will be available to farmers, who are often skeptical of the scale of their responsibility for nutrient pollution.
“Say for example I am a farmer and I farm 100 acres of area,” Remegio Confesor, the principal investigator for the modeling project, told Circle of Blue. “The big question is: How do I affect the whole million acres of the watershed? How much contribution do I have in terms of pollution to that?”
Historically, farmers didn’t account for much of the phosphorus entering Lake Erie. In 1968, only 4,000 metric tons, or 14 percent, of total phosphorus entering the lake each year was from agriculture and other nonpoint sources. At the time, 63 percent of the phosphorus came from municipal wastewater treatment plants. By 2002, however, nonpoint sources contributed nearly three times as much phosphorus to Lake Erie as industrial and municipal point sources. In 2011, just 7 percent of phosphorus entering Lake Erie through the Maumee River came from cities and industries.
The way phosphorus gets into a watershed is also important, according to Baker. Point sources generally discharge equal amounts of phosphorus each day, while phosphorus from nonpoint sources is flushed into the watershed in large quantities during rainstorms and snow melts. So even if individual farmers do not lose much phosphorus from their farms, the accumulation of runoff from millions of acres during a storm can lead to algal blooms—especially if the “pulse” occurs in the spring.
This theory raises questions about the role climate change might play in the intensity of future algal blooms if heavy rain events become more frequent, as research suggests they will. Scientists at the University of Wisconsin System’s Madison, Milwaukee and Green Bay campuses are tackling this question by integrating climate change models, hydrodynamic models of Green Bay, and biogeochemistry models describing how nutrients flow through the bay’s watershed. They hope the models will show what types of nutrient management practices will be most useful in the long run.
“One of the things we’re trying to do in the next go round is to link these models together and then develop a set of management tools which will allow managers to run those kinds of simple scenarios,” Val Klump, Associate Dean of Research and Professor in the School of Freshwater Sciences at UW-Milwaukee’s Great Lakes Water Institute, told Circle of Blue. “What if we put in these management practices and we have a longer stratified period, we have more intense precipitation events, we have a wetter system, we have warmer winters, what would that do to the biogeochemistry of the bay?”
Behind the reductions in phosphorus from factories, sewage treatment plants, and other point sources was the 1972 Clean Water Act. A legal monument to improving environmental quality, it did wonders to stop cities, utilities and manufacturers from spewing industrial chemicals, oils and phosphorus from their pipes. The CWA required these point sources to obtain National Pollutant Discharge Elimination System permits, and municipal wastewater treatment plants were required to install secondary treatment processes to remove nutrients like phosphorus. The binational 1978 Great Lakes Water Quality Agreement further required wastewater treatment plants in the Great Lakes basin to comply with a 1 milligram per liter limit on phosphorus in their effluent, and 75 percent met the requirement by 1984. The laws led to a decrease in annual loadings of phosphorus into Lake Erie from 28,000 metric tons in 1968 to 12,400 metric tons in 1982. The amount of algae in Lake Erie’s offshore waters declined 65 percent between 1970 and 1985.
These accomplishments required huge investments. The federal government spent $US 61.1 billion between 1970 and 1995 helping cities throughout the country meet the CWA standards. Another federal program, the Clean Water State Revolving Fund, has provided $US 50 billion to date for wastewater treatment improvements.
It has not been enough to cure the lakes of algal blooms. The Clean Water Act does next to nothing to address the nitrogen, phosphorus and sediments that wash unseen from millions of acres of farm fields, entering thousands of ditches and streams on their way to the big lakes.
In addition to summoning the political will, the trouble with ordering farmers to implement better management practices to curb phosphorous is that researchers also don’t know which practices help the most and where exactly they should be used within the watershed to maximize water quality improvements. And despite most of the blame for the excess phosphorus problems being put squarely on the shoulders of the agricultural industry, researchers also acknowledge that farmers may be losing only 2 or 3 percent of the phosphorus they apply per acre.
Rapid changes in farming technology over the past 30 years have vastly improved the precision with which farmers can apply fertilizer, Bret Margraf, a farmer and nutrient management specialist for Ohio’s Seneca County Soil and Water Conservation District, told Circle of Blue.
For example, farmers used to take 10 or 12 soil samples randomly with a soil probe from each field. They sent these samples to a lab for analysis and then applied phosphorus, nitrogen and other nutrients to the field based on the average need of the field. Soil types and nutrient content, however, can vary greatly across a single field, so now tractors can use GPS systems to break a field into 2-acre zones and take eight or 10 soil samples per zone. This creates a much more detailed picture of the field’s nutrient needs.
“Now what we’re able to do with equipment is we can apply nutrients specific to the needs of that zone,” Margraf said. “So this zone may require nothing, and the zone next to it may require very high levels. Just that alone equals out in savings in the long run, because instead of just treating the field as an average, you’re now treating the field as micro-areas.”
Technology is also available that can tell farmers how healthy a plant is and apply fertilizer accordingly. Sensors on fertilizer spray booms can take infrared images of growing crops, assign a health index to each plant based on the image, and then apply nutrients accordingly. Therefore, the amount of fertilizer being applied can continuously change as the farmer drives across the field.
Once the nutrients are applied to the field, the problem becomes keeping them there. Best Management Practices (BMP) like buffer strips—stretches of natural vegetation left along the edge of fields—and no-tilling can help trap nutrients and slow runoff into water bodies. One practice that is growing in popularity is the use of cover crops, such as hay, rye, radishes and sunflowers. These crops are planted in the offseason to avoid bare fields that are more susceptible to erosion and runoff. They also take nutrients like phosphorus out of the ground and store them in their leaves and roots. When the cover crops die, they return the nutrients to the soil so they can be used by the cash crops like corn and soybeans.
Margraf has seen growing interest in cover crops and other BMPs in the Honey Creek Watershed where he works. He said five years ago he struggled to get ten participants at educational meetings about cover crops, but now he gets as many as 100. Still, some phosphorus is bound to get into the watershed.
“The frustrating part with the whole phosphorus thing in Lake Erie is, we could only be talking about a pound to the acre loss,” Margraf said. “It’s such a small amount that they’re saying could be the difference between being a problem and not a problem. That’s almost to the point of zero tolerance, when it comes to loss. And zero tolerance is not practical in farm operations, because we’re subject to weather.”
The rise of farming technology has been accompanied by another trend—one toward bigger farms. By a measure of “midpoint acreage” of U.S. farms—half of U.S. cropland is on farms larger than the midpoint, while half of cropland is on farms smaller than the midpoint—farm size nearly doubled between 1982 and 2007, going from a midpoint of 585 acres to 1,105 acres. In 2011, farms with more than 2,000 acres—which account for just 2 percent of total farms—controlled 34 percent of all cropland in the United States. The USDA expects the trend to continue, given that larger farms typically have better financial returns.
Margraf, who farms 1,200 acres of corn, wheat and soybeans with his father, said BMPs can be especially tough to sell to the largest farms because their time is at a premium. “Unfortunately they’re the ones that are covering a good majority of our acres,” he said. “We’re talking guys that are 15,000, 20,000-acre farmers. Well think how many 500-acre farmers you have to deal with first just to offset what might be going on there.”
The algae, though, are undiscriminating. “The cause of the problem is the same: people putting too much of a nutrient into a lake,” said Chaffin of OSU’s Stone Laboratory. “Whether it’s from sewage or agriculture or manure or industry, once it’s in the lake, the cyanobacteria don’t care where it came from.”
Indeed, two weeks after Carroll Township was forced to shut down its water plant due to algal toxins, David Leffler, commissioner of water plant operations for the neighboring Toledo Department of Public Utilities, went before his city council. Leffler requested $US 1 million more in his budget to pay for more treatment chemicals for the city’s Collins Park Water Treatment Plant—which is the sole source of drinking water for half a million people in northern Ohio.
It was the second time in three years Leffler needed to ask for a higher annual budget. The city, wary of a public health crisis, paid. Toledo now allocates $US 4 million for water treatment chemicals annually, double the amount of the 2010 budget.
“Someone asked me if the toxin could get sufficient enough out in the lake that we wouldn’t be able to treat it,” Leffler said. “That’s always a concern. You can only take out so much.”
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