It's likely to be another summer of poor Bay water quality, according to the prediction by a team of scientists, who expect widespread low-oxygen conditions in the Bay's mainstem.

The scientists said that the high nutrient loads accompanying higher-than-average river flows, especially in late winter, are to blame for the conditions.

"Simply put, we're predicting that it's not going to be a good summer out there for the rockfish, crabs and oysters that call the Bay home," said Bill Dennison, of the University of Maryland Center for Environmental Science and leader of the forecast project.

According to the forecast, the Bay will have between 1.27 and 1.7 cubic kilometers of anoxic water-or about 3 percent of the mainstem Bay-which could result in the fifth largest amount of anoxic water since Baywide monitoring began in 1985. Anoxic water essentially contains no oxygen, making it a true "dead zone."

Scientists predict a larger area, about 9.9 cubic kilometers, will be hypoxic-having very low oxygen levels. That would be nearly a fifth of the Bay. If the forecast holds up, the Bay would have the sixth largest amount of hypoxia since 1984.

Scientists say conditions would be similar to 2004. That year, a large zone of hypoxic water covered deep water areas from the northern Bay to the mouth of the Rappahannock River.

Hypoxic water contains oxygen, but at such low concentrations that it can't sustain most aquatic life. The forecast considers water with less than 2 parts per million of oxygen as hypoxic, although many Bay dwellers actually require substantially higher concentrations to survive.

The forecast is based on the historical relationship between winter/spring nutrient loads and river flows and their impact on summertime Bay oxygen levels.

It is the fourth annual forecast of summer conditions made by scientists, and is intended to help the public better understand the relationship between actions on the land and Bay's water quality.

"The forecast shows restoration efforts need to be stepped up to break the continuing cycle of poor summer conditions," Dennison said. "We need to improve the way we manage every backyard, barnyard and boat yard in the region to get this Bay cleaned up."

Information about the forecast, including maps and methodologies, is available at www.eco-check.org/forecast/chesapeake/.