Hurricane Ian drained the waters of Tampa Bay. Has this affected the environment?

When Hurricane Ian hit the Florida peninsula, the receding of Tampa Bay was a sure sign of a tropical problem on the way.

Related: How reliable are hurricane models? Hurricane Ian gave us some answers.

It reminded many locals of Hurricane Irma, which also drained the bay five years ago. “Reverse Storm Storm” Ian revealed similar sights: the exposed sea floor. The boats at the moorings are empty of water. Curious passers-by ignore meteorological warnings and take a closer look at the strange phenomenon.

But with the water back in the bay and the storm long gone, researchers are now wondering: Did a reverse Storm Ian, which lowered water levels by more than 7 feet in some areas, change the amount of nutrient pollution in Tampa Bay? And if so, what does that mean for Gulf health?

A steady stream of people stopped along Bayshore Boulevard to see the aftermath of Hurricane Ian, which triggered a reverse storm surge that drew water from Hillsborough Bay on September 28 in Tampa.
A steady stream of people stopped along Bayshore Boulevard to see the aftermath of Hurricane Ian, which triggered a reverse storm surge that drew water from Hillsborough Bay on September 28 in Tampa. [ LUIS SANTANA | Times ]

“When it comes to nutrient management in the bay, hurricanes are one of the multiple, interplaying stresses that can affect bay health,” Elise Morrison, associate professor in the Department of Environmental Engineering Sciences at the University of Florida, wrote in an email.

Morrison and a team of researchers at the University of Florida have been sampling nutrients, including nitrogen and phytoplankton that fuel algal blooms, every two weeks in Tampa Bay since April 2021 — just as the Pine Point sewage disaster began to unfold. For Ian, they collected water samples before and after the storm at four locations across the bay: Pine Point Creek, Bishop Harbor, Joe Bay and St. Joseph Sound.

As the UF analysis wraps up, researchers at Texas A&M-Corpus Christi who studied a similar reverse storm in Corpus Christi Bay during Hurricane Harvey in 2017, say nutrient pollution “changed dramatically” in the days after the fall of Harvey.

Once the water level dropped by 3 feet – what the researchers called “hydrological clouds” – there were increases in ammonium and then a large pulse of nitrate and salt water about two weeks after landfall, according to a study published last month in Frontiers in Marine. Science, a peer-reviewed journal highlighting human interactions with the oceans.

“There is a connection between land and the sea,” said Dorina Morgoli, professor of hydrogeology at the university and author of the study. “When the sea level drops suddenly, you have a strong draw of groundwater heading toward the sea. It carries nutrients into the bay at a faster rate than usual.”

In general, whether backstorms are a silver lining or a downstream health defect depends on what each downstream needs and doesn’t.

“It could be good, because it could be nitrogen-enriched in the estuary of a depleted nitrogen river. But it could also be bad, and it brings a pulse of new nutrients that can lead to algal blooms,” Morgolet said in an interview.

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People ventured on foot to Tampa Bay to see the aftermath of Hurricane Ian, which created a reverse storm surge that drew water from Hillsborough Bay on September 28 in Tampa.
People ventured on foot to Tampa Bay to see the aftermath of Hurricane Ian, which created a reverse storm surge that drew water from Hillsborough Bay on September 28 in Tampa. [ LUIS SANTANA | Times ]

A preliminary report suggests that Hurricane Ian sucked more water from Tampa Bay than Irma did in 2017, and the last time a major hurricane triggered this frightening phenomenon.

Related: Florida sees rise in meat-eating bacteria amid Ian’s concerns

At its most extreme, the waters in Tampa Bay receded more than 7 feet, 1 inch below sea level, according to a post-hurricane report from the National Weather Service. It happened at the mouth of Hillsborough Bay just after 7:30 PM on September 28.

That’s nearly a foot more than during Hurricane Irma, which drained the bay a maximum of 6 feet, 1 inch below sea level at the entrance to Mackay Bay in 2017, according to Tyler Fleming, a National Weather Service meteorologist in Tampa Bay.

“The tides don’t usually come close to that maximum in the bay,” Fleming said. Low tide usually lowers the bay’s water level by two feet or less.

The unique shape of Tampa Bay, paired with Ian’s location, shaped what Fleming refers to as the “funnel effect.” As the storm approached the peninsula south of the Bay Area, counterclockwise winds began spewing the waters out. With nowhere to go but from the mouth of the bay, Fleming said, the effect of the receding waters is amplified.

Typically, it takes between one and three months for water quality effects to become more visible downstream after events like Hurricane Ian, according to Ed Sherwood, executive director of the Tampa Bay Estuary Program.

“It is unlikely that the water-quality implications of the negative rise and subsequent large influxes of the Ian Rain will be immediately apparent in the Gulf,” Sherwood wrote in an email. “We must learn more about the water quality benefits and effects from the storm’s passage over the next several months in Tampa Bay proper.”

Crowds gathered along Bayshore Boulevard for a closer look at the effects of Hurricane Ian, which triggered a reverse storm surge that drew water from Hillsborough Bay on September 28 in Tampa.
Crowds gathered along Bayshore Boulevard for a closer look at the effects of Hurricane Ian, which triggered a reverse storm surge that drew water from Hillsborough Bay on September 28 in Tampa. [ LUIS SANTANA | Times ]

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