WASHINGTON (AP) _ Scientists say this year’s summer “dead zone” in the Chesapeake Bay will be larger than average.

“Dead zone” refers areas of low or no oxygen that can kill fish and aquatic life.

Scientists with National Oceanic and Atmospheric Administration and the U.S. Geological Survey gave a forecast on the dead zone on Wednesday.

They say this year’s dead zone could be about 1.89 cubic miles, or nearly the volume of 3.2 million Olympic-size swimming pools.

According to measurements dating to 1950, the 30-year mean maximum dead zone volume is 1.74 cubic miles.

Officials say spring rainfall plays an important role in determining the size of the low-oxygen and no-oxygen zone. That rainfall in New York and Pennsylvania has led to higher streamflow in the Susquehanna River, delivering more nitrogen runoff.