Finger pointing over cause of phosphorus won't heal a dying lake

Sewage from municipal plants in Detroit, Toledo and other cities along Lake Erie contribute just as much phosphorus to the lake as manure and fertilizer runoff from farms,  according to a U.S. Geological Survey study. Phosphorus, a byproduct of sewage, fertilizers and manure, is responsible for the toxic blue-green algae that excrete liver and nerve toxins which can sicken people and kill fish and wildlife.

The study's finding that cities are just as much to blame as farms for toxic algae polluting Lake Erie comes as a surprise to Ohio's scientists, who previously thought that farm runoff was responsible for as much as 60 percent of phosphorus in Lake Erie, according to the Columbus Dispatch.

I have reported extensively on the algae issue and pass along Harmful Algal Bloom Bulletins as soon as I receive them. The algae threaten Lake Erie's $10 billion-a-year fishing and tourism industry. Algae cause "dead zones" in parts of Lake Erie and other bodies of water where no oxygen exists, making them uninhabitable.

The current bloom of algae in Lake Erie has caused public beaches at Maumee Bay and Kelley's Island to issue health warnings.

Peter Richards, a water-quality researcher at Heidelberg University's National Center for Water Quality Research, told the Columbus Dispatch that there is some discrepancy in the data; however, Geological Survey research hydrologist Dale Robertson said he stands by his computer modeling, which shows that sewage plant cleanup ordered by the government in the 1980s didn't cut enough phosphorous.

Maumee River is the leading supplier of phosphorous into Lake Erie, with 82.6 percent of it coming from farms, according to Heidelberg.  The second largest source of phosphorus is the Detroit River, with nearly 75 percent coming from sewage-treatment plants.

According to the study, here is how it breaks down: 42.1 percent of Lake Erie's phosphorous comes from sewage, 43.6 coming from farms, while the remaining nearly 15% comes from decaying plant matter in forests and lawn fertilizer that gets washed into storm sewers.

Sandy Bihn of Lake Erie Waterkeeper said officials should order further phosphorous cuts at Detroit's sewage treatment plant. The Ohio Farm Bureau Federation, Ohio's largest farm trade group, was quick to concur. The federation has been saying that farms are not solely to blame for algae in Ohio's lakes and ponds.

It looks like farms and sewage are about equally responsible here, with farms having a slight edge. But the larger point, I think, is that we know what's causing the explosion of phosphorus in the lake, so rather than fight over who's more at fault, or point fingers, we need to take action NOW. For the sake of the lake, the health of our families, and out very future.

To really understand and appreciate the problem, read Lake Erie Death Watch by Barry Yeoman.

Here's what I don't understand: Millions of people like myself enjoy all that Lake Erie has to offer and appreciate its large significance as a source of sustainable fresh water for ourselves and future generations, as well as an engine of economic health for the many millions of people who live near its shores. Erie has more consumable fish than all the other Great Lakes combined, provides drinking water for 11 million people, and is a major recreational and tourist attraction. It's of one of Ohio’s top economic engines, providing thousands of jobs and nearly a billion dollars in economic activity to the state.

So why are we treating it like a sewer?

The Dead Zone Revisited: A University of Michigan professor and his students work to solve the problem of hypoxia in Lake Erie

Don Scavia

A few weeks ago I wrote about the "dead zone", or hypoxia region, that forms in Lake Erie's central basin as a result of the presence of excessive nutrients in the lake, causing too much algae to grow and, in turn, consume precious oxygen in the water needed to sustain indigenous fish and plant life. It's such a serious problem, one that threatens Lake Erie's fragile ecosystem.

One of the guys on the front lines working to find solutions to this problem, Don Scavia, Professor of Natural Resources and Environment and of Civil and Environmental Engineering at the University of Michigan in Ann Arbor. Don and his students combine numerical models, laboratory and field work, and assessments to improve the understanding of interactions between human activities on land and their impacts on coastal marine and freshwater ecosystems. Don has also served on the Boards of Directors for the American Society of Limnology and Oceanography, the International Association for Great Lakes Research, and the Great Lakes Observing System.

In testimony before the Subcommittee on Energy and Environment Committee on Science and Technology in September of 2009, Dr. Scavia call hypoxia "an issue of global importance." He told the subcommittee that "the dead zone in Lake Erie, once thought to be under control and shrinking, has grown again to sizes not seen in decades." He went on to say:

Clearly, the nutrient pollution problem is not under control, and if more is not done to reduce this pollution to coastal and Great Lakes waters, we can expect further degradation and loss of important recreational and commercial resources.

In a recent article in the Great Lakes Echo, Dr. Scavia is attributed as saying that the dead zone in the central basin of the lake has grown up to two thirds of the entire lake in recent years. While cropland area has not substantially increased since the 1950s, agriculture intensification has brought loss of natural habitats and increased use of pesticides, fertilizer and manure which pollute the lakes. These factors, combined with heavy spring and fall precipitation, are thought to be the cause the increased hypoxia in the lake.

Dr. Scavia is currently heading up a study to establish the link between climate change, farming and dead zones, with the ultimate goal of helping farmers modify their practices to control their impacts on the lakes. One avenue to help lessen the impact, according to Scavia, would be amending the Farm Bill, a federal law that regulates agricultural practices, so that it allocates more funds and works towards land and water conservation.

Tell your representatives to fight for these changes in the Farm Bill and other measures that will help save Lake Erie.

In a balanced ecosystem (left) some nutrients fuel the growth of microscopic algae, which are the base of the aquatic food chain. In an unbalanced ecosystem (right), excess nutrients cause too many algae to grow. The excess algae die, sink to the bottom, and are decomposed by bacteria, which use up oxygen in the water. Image: google.com

What's It All About, Algae? Meet the Dead Zone!

Algae bloom is represented by green color seen in the western basin.  European Space Agency/NOAA Photo

As reported in Sunday's Toledo Blade, a huge bloom of potentially toxic microcystis algae, which has reared its ugly head almost annually since 1995 after more than a 20-year absence, has been visible from space since at least July 22. European Space Agency satellite photos (one example shown above) show it fanning out toward the Lake Erie islands.

Although the lakes always have small, natural concentrations of algae, heavy spring rain and near-record phosphorus runoff from farms and sewage networks, combined with dry, intense heat and stagnant air of recent weeks, are the likely driving forces behind the bloom.

A Lake Erie Harmful Algal Bloom Bulletin issued by NOAA on July 28 said the microcystis concentration in the algae is 500 times greater than the World Health Organization’s standard (20 micrograms per liter) for recreational water. Not all microcystis contains the deadly toxin microcystin. It is not known how much, if any, of the current bloom has that toxin. If it does, the potential health effects are serious.

Algae choked beach on Catawba Island

But problems associated with phosphorus runoff are not confined to Lake Erie's Western Basin. Stand by for The Dead Zone. No, I'm not referring to the Dead Zone of the Stephen King novel, nor do I mean the movie or TV series of the same name. No I'm referring to the dead zone in Lake Erie.

In recent decades, the bottom waters in the Central Basin of Lake Erie have become anoxic in the late summer. Anoxic means without oxygen. Aquatic creatures, including fish and bottom-dwelling animals, need oxygen in the water to live or they suffocate. The fish may be able to swim to better waters, but most of the other animals cannot. Commercial fishermen of the Central Basin are all too familiar with the dead zone.

The reasons for this annual dead zone were, at first, unclear. So, in June 2002, the U.S. Environmental Protection Agency in cooperation with many universities and other agencies in the United States and Canada, began an intensive special study to determine the cause of the oxygen depletion in Central Lake Erie.

The study concluded that while the unique configuration of Lake Erie's Central Basin is largely responsible for the problem, too many nutrients, especially phosphorus, make the problem much worse. Most of the excess phosphorus comes from human activities, including sewage treatment plants and agriculture. This animation gives a simplified explanation of how oxygen depletion develops:

The EPA monitors oxygen depletion levels in Lake Erie by taking samplings and doing surveys, primarily from its vessel, Lake Guardian, the only self-contained, non-polluting research vessel on the Great Lakes.

The problems of algae blooms in western Lake Erie and the dead zone in the central basin of the lake are going to be with us for the foreseeable future. These problems are going to require solutions - and vigilance. At a time when funding is becoming scarcer by the year and some politicians suggest killing or at least gutting the EPA and other environmental agencies, the answers are not going to be easy to come by.