Swamped farm fields and gorged rivers could worsen pollution worries for the flooded Lake Champlain because of the high amount of phosphorus that has washed into it, officials said Tuesday.
Snowmelt and heavy rains caused the Winooski River to dump into the lake in the last week of April about 77 metric tons of phosphorus, about half of what the river puts in the lake in a typical year, said Eric Smeltzer, an environmental scientist with the Vermont Department of Environmental Conservation.
On one day alone, 28 metric tons came down the 90-mile-long river in northern Vermont, he said.
"That's more than the amount of phosphorus that's discharged to the lake from all 60 wastewater treatment plants in Vermont in the Lake Champlain Basin in one year," he said.
The added phosphorus _ a plant nutrient found in manure and fertilizer that contributes to weed growth and toxic algae blooms _ could lead this summer, he said, to more algae blooms in the lake, which is situated mainly in Vermont and New York but extends into Canada.
Algae blooms are rapid increases in the amount of algae, which can discolor the water and reduce its oxygen content, killing plants and animals. The blue-green algae blooms that have turned up in the lake also can be toxic, with warnings issued not to swim near them because they can cause irritations or rashes and that consumption of pieces of them can lead to diarrhea, vomiting or nausea.
Spring runoff into Lake Champlain happens every year, but this year it's extreme, Smeltzer said.
The freshwater lake, which has reached record levels because of heavy April rain and runoff from melting snow, has receded with dry weather in recent days but was still past flood stage on Tuesday. Gov. Peter Shumlin's administration estimates nearly 600 homes have been damaged by flooding.
Disaster specialists from the Federal Emergency Management Agency were in the state Tuesday, assessing damage inflicted to public infrastructure by the floodwaters in seven of its 14 counties. They'll compile data and help Vermont Emergency Management make a recommendation to Shumlin about whether to request a federal disaster declaration.
Joint state and FEMA teams also were out looking at roads, bridges and waterside parks in five of the 22 New York counties that reported flood damage. But they had not been called in to assess hard-hit Clinton County because the flooding continues, said Dennis Mihalski, spokesman for the New York Emergency Management Office.
"You can't see the damage where there's still standing water," he said.
The high water wasn't causing any major problems at sewage treatment plants in Vermont because most of the treatment plants along the lake are far enough above the flood plain to not be affected, said Brian Kooiker, of the DEC's wastewater division.
But other problems could be uncovered when the water recedes, FEMA officials said.
"You don't know how much erosion there's been, how many banks have been undercut, whether or not you're going to expose septic systems to that, whether or not those are going to fail," FEMA environmental specialist Marie Thomas said.
Much of the phosphorus will settle on the bottom of the lake and more will leave the lake at the outlet of the Richelieu River in Quebec, "but some of it will probably hang around and could contribute to worse algae blooms this summer," Smeltzer said.
"What we can say, though," he said, "is that in the long term the more phosphorus in the lake the more likely we are to have problem algae blooms."
Associated Press writer George Walsh contributed to this report from Albany, N.Y.