Record phosphorus level spurs worry for Maumee River; cause unknown

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A record level of phosphorus has been found this year in the Maumee River since a monitoring program of the waterway began in 1975.

The finding of some 261 tons of dissolved phosphorus spanned sampling from April 1 through June 1 and follows a recent uptick of the presence of phosphorus in the river.

Phosphorus is the region's most common farm fertilizer. It also helps algae to grow, which in turn depletes oxygen and can cause fish to die.

While area farmers have generally pleased state officials with a slight reduction in phosphorus-laden field dirt they've let get into the Maumee River in recent decades, scientists still have documented a 15-year upswing in phosphorus that's dissolved in the water column.

Nobody knows why. But to Gail Hesse, chairman of the Ohio Lake Erie Phosphorus Task Force, it's a dichotomy that needs to be addressed right away - or risk having western Lake Erie's ever-growing algae problem shoot off the charts.

"It's complex. We're not quite sure what's happening and what all of the trigger points are, but that shouldn't stop us from acting," said Ms. Hesse, an Ohio Environmental Protection Agency manager and an administrator of the agency's Lake Erie and surface drinking water protection programs.

When many of today's pollution laws were enacted in the 1970s, removing phosphorus was identified by the United States and Canada as a top priority for the Great Lakes.

Algae dissipated as sewage plants became more sophisticated, removing much of the phosphorus that comes from human waste. But now, with the soluble form of phosphorus on the rise, the algae's back.

Phosphorus in its dissolved state is 3.5 times more accessible to algae than phosphorus in a crystallized, solid form that clings to sediment, according to Heidelberg University's National Center for Water Quality Research.

The venerable Maumee River, which supplies western Lake Erie with much of its water, had its highest concentration of dissolved phosphorus during the annual April 1 thru June 30 sampling period since the Heidelberg center started collecting data in 1975.

A staggering 261 tons (237 metric tons) of dissolved phosphorus moved past the center's sampling station near Waterville.

During the same three-month period, 51.5 tons (46.7 metric tons) of dissolved phosphorus was detected at the Sandusky River's sampling station near Fremont - the second-highest in 35 years of monitoring. The Sandusky is another one of the lake's largest tributaries, according to Heidelberg.

"The dilemma is we have succeeded in reducing suspended sediment, so erosion control is working. What's increasing is the amount of dissolved phosphorus," Ken Krieger, the Heidelberg center's director, said.

Officials are looking harder at how fertilizers are applied, not just whether the field dirt is retained, Mr. Krieger said.

They are looking at livestock manure, and other potential sources.

Western Lake Erie, which geographically spans roughly from Monroe to Sandusky, is often the first place where algae is found in the Great Lakes region. There's the phosphorus-loading and the urbanization - but also the sheer fact that the water is the shallowest there. That means it warms up faster, especially during the recent heat waves.

In Lake Erie's central basin, northeast of Cleveland, lies the infamous dead zone - a pocket of oxygen-depleted water that has changed in size and has likely existed for centuries. It can't support fish or other forms of aquatic life.

Scientists don't know why it has been larger in some years than others. But it's in everyone's best interest to keep algae from proliferating and robbing the western basin of oxygen, too, Mr. Krieger said.

"What goes on in the western basin ends up drifting over to the central basin," he said. "That just makes the dead zone in the central basin worse."

Contact Tom Henry at:

thenry@theblade.com

or 419-724-6079.