Should Tampa dye the Hillsborough River green for St. Patrick’s Day? A petition says no.

A petition to stop the city of Tampa from dyeing the Hillsborough River a bright shade of electric green for St. Patrick’s Day is gaining traction among the region’s angling community.

The social media movement was launched Sunday by Tampa Bay fly fishing guide Capt. Dustin Pack. He said the annual River O’Green Fest tradition negatively affects fish and wildlife populations in the days after the event — and sends the wrong message about environmental stewardship.

“You can party and also not dye our river green,” Pack said in an interview with the Tampa Bay Times. “It just doesn’t look good that we say we care about an estuary that we live on or live near, but we’re just throwing this crap in it.”

As of Wednesday afternoon, Pack’s petition had drawn more than 2,000 signatures and had the backing of powerhouse Florida angling organizations such as Captains for Clean Water and Florida Sportsman magazine.

The effort will likely be futile, though: Crews plan to dye the river Friday between the Cass Street Bridge and Kennedy Bridge. The city maintains the dye is harmless and safe for the environment: It’s nontoxic, biodegradable and certified for drinking water systems, said Liz Hall, a spokesperson for the Tampa Water Department.

The military uses the same dye to mark the location of downed pilots during search-and-rescue operations at sea, Hall said in an emailed statement. According to the event’s webpage, the dye is used in food and in eye surgery to trace blood vessels.

Hall also cited reports from the U.S. Environmental Protection Agency that claim the dye is safe for aquatic environments and noted it’s certified by the National Sanitation Foundation, or NSF.

Roughly 300 gallons of the dye mixture is used during the event, according to Hall. It cost about $16,000 and was paid for by Grow Financial, a Tampa-area federal credit union. The annual tradition started in 2012 when Bob Buckhorn was mayor.

‘Fish may skip a meal’

There are a few environmental factors to consider when something like dye is added into a river, according to Steve Murawski, a fisheries biologist at the University of South Florida. For one, it could change the turbidity — or the amount of light that reaches the bottom of the river.

“You may lose a little phytoplankton production, but probably not a lot,” Murawski told the Times. The plantlike organisms are the base of the marine food web. “Over a short period of time, some predators likely couldn’t find their prey. Fish may skip a meal, but they skip meals all the time.”

Another factor is how fast the water is moving. The faster the water flows, the quicker the dye will dissipate.

“Eventually it’ll all move out into Tampa Bay, where it dilutes further.”

Emptying dye into the river doesn’t require a permit from the Environmental Protection Commission of Hillsborough County, according to Sam Elrabi, director of the commission’s water department.

“We have never documented any environmental issues,” Elrabi said in an interview with the Times. “It’s a limited-duration event — the dye dissipates after a few hours. (The commission) is not involved in it, and therefore we don’t have an objection to the dye, based on the characteristics of the dye itself.”

The specific area in the river where the dye is released sees large tide changes, Elrabi said.

“The stuff dissipates,” Elrabi said. “It doesn’t sit and it doesn’t linger.”

Pack, who regularly launches his boat out of the Hillsborough River, takes issue with the idea that the dye disperses after a few hours. He claims the tradition manipulates the eating habits of both fish and birds in the days after the event when he’s out on the water and deprives the ecosystem of needed sunlight.

“It just settles on the bottom,” Pack said. “It’s overall an unnatural look for the river. It’s completely changing the estuary to where we can’t see fish anymore.”

At a time when water-quality issues like toxic red tide blooms and sewage spills are popping up across Florida, it’s “probably not a good idea” to put anything artificial or human-made into a river environment, according to Loraé Simpson, a seagrass researcher and director of scientific research and conservation at the Florida Oceanographic Society.

Hundreds of animal species call the nearly 60-mile Hillsborough River home, from dolphins and manatees to wood storks and snowy egrets, according to the Southwest Florida Water Management District. The Florida Department of Environmental Protection considers the river “impaired,” which means it’s a waterbody in need of restoration. Neither the water district nor the department provided comments on the petition.

“We just had 630,000 gallons of raw sewage dumped into the river this January,” Pack said, referring to a recent Times story that documented the spill. “It’s also littered with trash. And now we’re dyeing it neon green? We’re doing our best to try and destroy this river.”

Pack said he’s personally a fan of the St. Patrick’s Day holiday and maintains he’s not trying to cancel any parties or events.

“I love to celebrate the day. But we don’t have to dye a river green just for people to show up,” he said. “Just because Chicago does it, doesn’t mean we have to do it.”

The Chicago River has been dyed green for the St. Patrick’s Day holiday for decades.

Regardless of the environmental impact, emptying dye into the river may send a message to the general public about how we interact with the river that flows through Tampa, according to Maya Burke, assistant director of the Tampa Bay Estuary Program.

“I think when folks speak out about this sort of activity, it almost misses the point to respond with what the science says. Science and safety are certainly important, but more data may or may not change our policies, actions, and choices,” Burke said in an email to the Times.

“What I hear is a question about symbolic value — the Hillsborough River is the beautiful centerpiece of the city of Tampa, as is — why do we have to make it kelly green in order to celebrate?”