An independent, bi-national organization created by Canada and the United States has recommended swift and widespread limits on the use of phosphorus fertilizers in the Lake Erie watershed, according to the Wildlife Management Institute. The International Joint Commission (IJC) recently released a report, A Balanced Diet for Lake Erie: Reducing Phosphorus Loadings and Harmful Algal Blooms, which provides 16 specific recommendations to reduce phosphorus loads in the lake by both agricultural and urban sources.

"The public has told us, and research has confirmed, that Lake Erie is impaired by an excess of nutrients that feed harmful algae," said Lana Pollack, U.S. chair of the IJC. "We commend the U.S. and Canada for their work and investments to help Lake Erie, but it's time for governments at all levels to put the lake on a diet by setting targets and achieving real reductions in nutrient loads."

Phosphorus in the lake stimulates the growth of algae causing two major problems. First, the algae itself is toxic enough to kill animals and make people sick. Second, when the algae die, they fall to the bottom of the lake and rot using much of the available oxygen dissolved in the water and creating a "dead zone" where fish and other aquatic organisms can't survive. Algae blooms in the lake are so large and concentrated they can be seen from space. The largest algae bloom on record for Lake Erie occurred in 2011 and covered 1,930 square miles. The IJC report estimates that phosphorus levels in the lake must be lowered by 46 percent to cut the size of the dead zone in half.

Laws put in place in the 1970's substantially reduced phosphorus levels in the lake mostly from steep reductions in the nutrients coming from wastewater treatment plants. This, in part, helped trigger a boom in sport fish populations and recreational fishing that lasted three decades bringing millions of dollars to the region annually.

The report indicates that there are currently several sources of phosphorus getting into the lake such as lawn fertilizers and leaking septic tanks and that overall, the total phosphorus load in the lake has not risen much since the mid-1990's. It goes on to point out that while total phosphorus levels have remained fairly stable, levels of Dissolved Reactive Phosphorus (DRP) have more than doubled during that time. DRP is the type most easily used by algae and is also a main ingredient in fertilizers used to stimulate growth of corn. Scientists that worked on the report pointed out that as the climate has warmed in recent years, more intense rain events have increased the fertilizer runoff from farm fields into the lake.

The IJC has recommended a mix of voluntary and regulatory restrictions to reduce the amount of phosphorus getting into the lake and has set the year 2022 as the time frame to meet target levels. (pmr)