High levels of contamination caused beaches around the Great Lakes to shut down more than 3,000 times in 2008. That’s according to a new report released by the Natural Resources Defense Council.

The study says in 2008 test samples from Great Lakes beaches had E. coli levels twice the national average. Sadhu Johnston is the Chief Environmental Officer of Chicago. He says much of the E. coli found in the city’s beaches comes from…

JOHNSON: Seagull poop. And so if someone comes down to the beach, they have a picnic. They leave a bunch of food behind them. The seagulls come and eat it. They poop on the sand. That washes into the water and you get a spike in E. coli levels.

The report says overall there was a 10 percent decrease in national beach closures from 2007 to 2008. The Chicago Park District says the city had about a 30 percent decrease in shutdowns during that time. Regionally, the study ranked Chicago near the top when it comes to monitoring the waters and warning beach-goers.