June 15 (UPI) -- The latest forecasting models are predicting a larger-than-average dead zone in the Chesapeake Bay this summer.
The dead zone, an area with little to no oxygen, is expected to reach a peak size of 1.89 cubic miles -- the equivalent of 3.2 million Olympic-size swimming pools.
Dead zones are triggered by excess nutrient runoff from agriculture and wastewater. Precipitation totals play a large role in determining the size of seasonal dead zones. As in, more rain equals more runoff.
Excess nutrients, like nitrogen and phosphorus, feed algae blooms in the Chesapeake, which rob the water of oxygen, making life untenable for other marine organisms. Dead zones can kills thousands of fish and other species.
"The forecast calls for an above-average dead zone in the Chesapeake Bay this year, illustrating that more work needs to be done," Don Scavia, an aquatic ecologist at the University of Michigan, said in a news release. "The dead zone remains considerably larger than the size implied by the targets set under the Chesapeake Bay Total Maximum Daily Load agreement."
Scavia is one of several scientists who helped design the forecasting models. The research team also builds dead zone prediction models for the Gulf of Mexico and Lake Erie. Their work is funded by the National Oceanic and Atmospheric Administration.
Scientists use historic patterns to analyze NOAA data from streamflow gauges and water-quality samples -- and to predict future dead zones.
The Susquehanna River is responsible for most of this year's increase in runoff, as New York and Pennsylvania received large amounts of spring precipitation.
"Despite this year's forecast, we've made great strides in reducing nutrient pollution from various sources entering the Chesapeake Bay, and we are starting to see positive long-term signs," said Rob Magnien, director of NOAA's Center for Sponsored Coastal Ocean Research. "However, more work needs to be done to address indirect nutrient pollution from farms and other developed lands, to make the bay cleaner for its communities and economic interests."