To fill or not to fill holes is subject of bay study
By CRAIG PITTMAN, Times Staff Writer
ST. PETERSBURG -- Most of Tampa Bay is a shallow bowl, no more than 12 feet deep on average. But scattered on its bottom are more than 20 holes, acres in size and up to 40 feet deep.
The holes date back decades, to a time when the bay was seen not as a resource to be protected but as the source of fill dirt. From the 1920s until the '70s, developers gouged the pits in the bay bottom and used the dirt to transform swampy land into dry land that could hold houses.
Some of the holes have become repositories for pollution. Their lowest depths are devoid of oxygen and their bottom is covered by muck. But others are a favorite winter hideout for trout and red drum.
Now biologists, fishing guides, local officials and other experts are launching a study of whether some of Tampa Bay's holes ought to be filled, and if so, which ones. The study, expected to last two years, will explore a situation that has already prompted some disagreement.
"Just because it's a hole doesn't mean it needs to be filled in, necessarily," said Hillsborough County Commissioner Jan Platt, an avid angler.
Peter Clark, director of the nonprofit watchdog group Tampa Baywatch, agreed that the holes provide some benefit for the bay, "but I'm not sure that outweighs the problems they cause."
The study, led by the Tampa Bay Estuary Program using a $150,000 federal grant, is designed to figure out first what lives in the holes.
Then it will look at whether the bay's health would be improved by filling the holes completely and planting sea grasses, or partially filling them, or just leaving them alone. There has also been a suggestion of dropping artificial reef material into them to attract even more fish.
"It's going to be a balancing act," Clark predicted.
Tampa Bay is Florida's largest open-water estuary, covering 398 square miles at high tide. Its sea grasses need sunlight and clean water to grow well, and provide both food and habitat for many marine species, so they are an important measure of the bay's health.
When the holes were dug decades ago, it destroyed important sea grass beds. Homes were not the only things built atop the relocated fill. The beach at North Shore Park in St. Petersburg was created by dredging a 30-acre hole in the bay just offshore.
MacDill Air Force Base's recreational beach had a similar origin, leaving a hole estimated at 5 to 7 acres. MacDill also used fill from the bay to extend its main runway, leaving a 15-acre hole.
On the Hillsborough side of the bay, there are holes off Rocky Point, Culbreath Bayou and Whiskey Stump Key. The Pinellas side has holes off Shore Acres, Venetian Isles, the Howard Frankland Bridge causeway and the St. Petersburg-Clearwater Airport.
The holes are not the bay's deepest man-made gouges. Somewhat deeper are the shipping channels dug to accommodate traffic for the Port of Tampa.
To keep the channels open, every year the Army Corps of Engineers digs out 700,000 to 870,000 cubic yards of fill from the bay bottom. The Army would like to use the fill for a good cause.
A couple of years ago, at the suggestion of the state Department of Environmental Protection, the corps used some dredged material to fill one of the holes off MacDill Air Force Base. It ran out of material before it could fill it completely, however.
That hole "is located in the middle of sea grass beds, and if filled to the proper elevation could allow for sea grass recolonization," explained Bill Fonferek, a biologist with the corps' Jacksonville office.
Tampa Bay's anglers, including Hillsborough Commissioner Platt, objected. "We said, 'Hold it, there's a need for sea grasses but there's also a need for holes,' " Platt said.
Although Fonferek said the project was checked by federal wildlife officials, area anglers feared the corps was filling holes willy-nilly, without any concern about the fish that hide inside some of them.
"If you fill those holes in -- it's unthinkable," warned Jimmy Storey, 60, a professional guide who has been fishing in the bay for 45 years. "You're messing with things that shouldn't be messed with."
However, Fonferek said, it's not the entire hole that pulls fish in.
"The edges of the holes are what really attract the fish," Fonferek said. "One small fish can get out of the tidal flows (in a hole) because there's less current there and they can sit and not use as much energy. . . . The little fish can feed, and the big fish know where the little fish settle."
Meanwhile, down in the bottom, the holes "trap silt and sediment from upland runoff, so there are layers of muck at the bottom, and depending on the depth, there's less oxygen at the bottom so not much lives down there," Fonferek said.
The Tampa Bay Estuary Program study will take input from the corps, but also from anglers such as Storey and Platt.
"We want to take a look at each hole and make measurements," said Holly Greening, the estuary program's senior scientist. "We'll ask a committee of anglers to evaluate their ecological function. The Corps of Engineers is going to be providing an engineering evaluation of each one: the depth, the volume, how far they are from the areas that might be dredged."
That's important because some holes may be too far from the shipping channels, and so carrying the fill to them would cost too much, Fonferek explained.
Clark, whose group did a small-scale study of the holes two years ago, said that filling the holes could easily bring back sea grass beds crucial to the health of the bay. For proof, he points to St. Petersburg's Lassing Park, where the city filled an offshore hole in 1983 after two people drowned in its depths. Sea grasses sprouted up in short order, and now that section of the bay is indistinguishable from other parts that were never dug out.
But to anglers like Storey, the bay is doing fine with the holes, as evidenced by the resurgence of sponges and other sea life. Filling them in would be fixing something that may not be broken.
"The state of the bay now is the best it's ever been," Storey said. "Don't mess with it now. I mean, we've got sponges out the ying-yang coming back over there."
-- Times staff researcher Caryn Baird contributed to this report.
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