Swimmers approach the eastern edge of the Chesapeake Bay during the Great Chesapeake Bay Swim on June 13. More than 600 people participated in the fundraising event. (News21 Photo by Brian Hooks.)

News21 reporter Kate Yanchulis wrote the following — part of a longer story published by several area news organizations:

SANDY POINT STATE PARK, Md. – Hundreds of swimmers from across the country churned through the waters of the Chesapeake Bay on Sunday, and for the participants of the Great Chesapeake Bay Swim, nature cooperated.

The favorable conditions – the water at a balmy 74 degrees, the sun shining, the currents flowing toward the finish line – allowed all but 21 of the 618 swimmers to finish the 4.4-mile charity marathon, said Director Chuck Nabit. Last year, strong currents prevented more than 100 swimmers from completing the race.

While many participated for the sheer physical challenge, others also saw it as a showcase of the region’s natural treasure.

The water looked clean on the surface, and some of the participants were pleasantly surprised by the quality of the water. Dr. Bill Dennison, vice president for science applications at the University of Maryland Center for Environmental Science, said the water quality was the best it has been in several years.

But about a third of the course crossed a “dead zone,” or an area of the water with little to no oxygen, making it hostile to aquatic life.

The dead zone stretches 90 to 125 miles long and six miles wide every summer, according to Dr. Mike Roman, lab director at the University of Maryland Center for Environmental Science. That comes to about 10 percent to 15 percent of the total volume of water in the bay, as pollution from nutrients such as nitrogen and phosphorous causes huge algae blooms, which take almost all the oxygen out of the water.

Read full story from Yanchulis.

See photos on Flickr by News21 staffer Jason Lenhart