FORT WAYNE – Pollution in the Maumee River that causes huge “dead zones” in Lake Erie is at the highest it’s been in 35 years, and researchers do not know why.
A report this week by the National Center for Water Quality Research at Heidelberg University in Tiffin, Ohio, said the amount of dissolved phosphorus in the Maumee – one of the lake’s two biggest tributaries – is the highest ever recorded since monitoring began in 1975, when Lake Erie was known as a “dead lake.”
From April 1 through June 30, 261 tons of dissolved phosphorus moved past the university’s monitoring station on the Maumee near Waterville, Ohio, the report said. That’s up from less than 50 tons in 1995.
“It’s been a bit of a surprise to all of us,” said Greg Lake, interim director of the St. Joseph River Watershed Initiative and executive director of the Allen County Soil and Water Conservation District. “It’s hard to grab a hold of it.”
The St. Joseph River Watershed Initiative is a non-profit partnership dedicated to protecting and restoring the St. Joseph River and the nearly 700,000 acres it drains in six counties across three states. The St. Joseph is a major tributary to the Maumee.
Lake said that though the area has had a dry summer, the spring was wet, and some of the rains were intense, possibly contributing to the amount of phosphorus running off farm fields.
Phosphorus is a nutrient for aquatic plants, and when levels are high it feeds huge blooms of algae in Lake Erie. When the algae die, their decay uses up the oxygen in the water, making it unable to sustain life. Lake Erie’s comeback had been hailed as a triumph of environmental protections, but in the 1990s “dead zones” began returning. As the amount of dissolved phosphorus in the Maumee and Sandusky rivers has increased since then, so has the size of the dead zones.
The amount of dissolved phosphorus in the Sandusky is the second highest in 35 years, and boaters and fishermen have already reported large amounts of algae in the western basin of Lake Erie this spring and early summer, the report said.
Why the amount of dissolved phosphorus continues to increase is a mystery, because the trend is opposite that of particulate phosphorus. Particulate phosphorus is particles of the element that are attached to sediment in the water, while dissolved phosphorus has become part of the water itself and is far easier for algae to use, the report said.
Decades of conservation practices have dramatically reduced the amount of particulate phosphorus in the rivers, the report said, which makes the increase in dissolved phosphorus even more puzzling. Farm practices such as no-till farming, buffer zones and better timing of fertilizer application – embraced by farmers nationwide – have kept tons of phosphorus on farm fields and out of the rivers.
“Agricultural pollution abatement programs have focused on practices that reduce suspended sediment and particulate phosphorus export. Those practices have been very effective in doing that,” David Baker, coordinator of Heidelberg’s tributary monitoring program, said in a written statement announcing the report.
“However, some of those same practices can increase dissolved phosphorus export. Given the trends in increasing dissolved phosphorus export … the deteriorating conditions in Lake Erie, it is clear that ways must be identified and implemented to reduce dissolved phosphorus runoff from area cropland.”
Some of those steps could come soon. Ohio Gov. Ted Strickland on Friday announced a series of short- and long-term plans to clean up Grand Lake St. Marys.
State regulators say the lake is no longer safe for swimming, boating or fishing because of toxins from an algae outbreak, The Associated Press reported, and are investigating illnesses and dog deaths to see whether if they are linked to the lake water. Among the plans being considered is forcing large farms to reduce the amount of manure put on fields to reduce runoff.
“Major efforts are now being mounted to identify the causes of the increasing dissolved phosphorus runoff from cropland and sets of agricultural practices that will reduce dissolved phosphorus export,” the report said.
