TRAVERSE CITY, Mich. (AP) -- Sharp cutbacks in phosphorus runoff into Lake Erie are needed to counter a worsening problem of algae blooms that degrade water quality, harm fish and chase away tourists, a U.S.-Canadian agency said in a report to both governments Thursday.
The International Joint Commission, which recommends policies dealing with the Great Lakes and other border waterways, recommended targets for lowering daily amounts of phosphorus flowing into the ailing Erie. It's the smallest of the five lakes yet has the most abundant fish population and supports a billion-dollar angling and boating industry.
The commission said the level must drop by 46 percent to shrink by half a "dead zone" where algae saps so much oxygen that fish can't survive. It called for a 39 percent decrease on the western side of the lake where algae blooms have been particularly widespread.
Phosphorus, a nutrient that feeds algae, was among pollutants that had so degraded Lake Erie by the 1970s that some declared it dead. The problem improved significantly with laws requiring steep reductions in phosphorus releases from wastewater treatment plants and factories. But it returned in the late 1990s and has steadily worsened. A bloom in summer of 2011 was the largest on record, coating a 1,930-square-mile surface area with greenish slime.
The algae is poisonous enough to kill animals and make people sick. An Ohio township last year ordered residents not to drink tap water for two days because of algae pollution, while Toledo and other cities have tested and treated their supplies. When the algae dies, foul rotting mats wash onto beaches or sink to the bottom, robbing the water -- and fish -- of oxygen.
The report largely blames the algae's resurgence on manure and chemical fertilizer from farms, along with urban sources such as lawn fertilizers, pet droppings, leaky septic tanks and storm water drains. It proposes designating the lake as an impaired waterway under the federal Clean Water Act to force phosphorus limits.
"It's time for governments at all levels to put the lake on a diet by setting targets and achieving real reductions," said Lana Pollack, chairwoman of the commission's U.S. section.
The reduction targets should be met by 2022, the report said.
Overall levels have not risen since the mid-1990s, according to the report, based on two years of study by more than 60 scientists with universities, private firms and government agencies. But a type called dissolved reactive phosphorus, or DRP, has more than doubled -- and it's the variety "most easily used by the algae for growth," said Don Scavia, director of the University of Michigan's Graham Sustainability Institute.
DRP chemical fertilizers are popular for producing corn used as animal feed on large industrial farms, Scavia said. Manure also can undergo a process that generates DRP. In the past couple of decades, farmers increasingly have applied both in fall and winter, when the material sometimes has remained atop frozen ground or snow instead of soaking in. Farmers also have done less tilling.
Such changes prevented fertilizers from being worked into the soil, making them more apt to wash into streams and eventually the lake during the spring melt, Scavia said. As the climate has warmed, more intense rainstorms have boosted phosphorus flushing.
The report urges states in the Lake Erie watershed, including Michigan, New York, Ohio, Pennsylvania and Indiana -- as well as the Canadian province of Ontario -- to ban spreading farm fertilizers on frozen or snow-covered ground.
Farm groups acknowledge a role in the problem but favor voluntary best-management practices to cut down on runoff, such as making sure fertilizer comes in contact with the soil, said Larry Antosch, environmental policy director with the Ohio Farm Bureau. Regulations don't allow enough flexibility, he said.
"What works for you might not work for me, depending on the size of the crop, location and the type of crops you're growing," Antosch said. "We can all take different paths and get to the same spot."
Pollack said voluntary practices, while helpful, aren't enough.
"If they were succeeding, we would not be suffering the worst algal blooms in the history of the lake," she said.
To cut down on urban runoff, the report recommends stepped-up use of "green infrastructure" such as permeable pavement that lets rainwater soak into the ground. It calls for a 10 percent increase in coastal wetland acreage and more research and monitoring of phosphorus levels.
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