Thousands of volunteers flocked to the California coast and waterways on Saturday to participate in the 40th annual California Coastal Cleanup Day.

The event, which is the largest single-day volunteer event in the world, according to Guinness World Records, invited eco-friendly volunteers across the state to pick up trash along coastal areas ranging from Lake Tahoe to the San Francisco Bay.

According to the California Coastal Commission, which organizes the event, 28,751 volunteers scoured over 750 cleanup sites removing over 254,772 pounds of trash and recyclable materials. These numbers are likely to increase, given only 60% of cleanup sites had reported final numbers as of Monday.

Volunteers diligently tracked each item collected, with the data being examined by the Coastal Commission to better understand marine debris over time. Volunteers are asked to report their cleanup efforts at www.coastalcleanupday.org.

The Coastal Commission reports that approximately 75% of the waste collected by volunteers over the past 40 years is plastic. Additionally, 80% of the trash collected originates on land before eventually making its way into waterways and draining out to the ocean.

Each year, volunteers are asked to pick up the most unusual items they can find and send a photo to the Coastal Commission with the chance to win a prize. This year, the coastal winner was a volunteer who found $68,000 worth of cashier's checks in Los Angeles County. The inland winner found two large cowboy and cowgirl figurines in Contra Costa County.

“Californians really turned out for our coast today,” Coastal Commission executive director Kate Huckelbridge said Saturday. “All across the state volunteers rolled up their sleeves to protect our beautiful beaches, estuaries and waterways, just as they have for the past 40 years. They inspire all of us to remain vigilant in our work of protecting our coast and ocean for generations to come.”