TAMPA, Fla. (WFLA) — City of Tampa officials will turn the Hillsborough River green on Friday as they test the dye ahead of River O’Green Fest.

The festival isn’t until March 18, but downtown Tampa will get a preview of the festivities during the test. Turning the river green has been an annual St. Patrick’s Day tradition since 2011

“The dye is safe for the environment, non-toxic, biodegradable, meets all EPA standards, and is certified to comply with National Sanitation Foundation Standard 60,” the city wrote in a release on Friday. “This is the same dye often used in eye surgeries, food, and water systems to trace the flow of drinking water.”

River O’Green Fest kicks off at 11 a.m. on March 18 at Curtis Hixon Waterfront Park.