Conservation Front - Florida Bays

Within a few minutes of meeting Bruce French at a Florida Sportsman Fishing Show, he had pulled out a pad and started sketching a design of his idea for subsurface inlets. Frankly, I wasn't sure what to think. Surely this was a screwball idea-drill a 4-foot diameter pipe beneath a barrier island so you can pump sea water directly into an estuary.

But the more we talked, the more it made sense. And unless some miracle of stormwater management occurs in Florida over the next few years, his idea may turn out to be our best hope for restoring and maintaining some of Florida's most threatened estuaries.

Called T.A.W.E.S. for Tidal Activated Water Exchange System, the manmade inlets would introduce clean sea water into coastal systems that for the past couple of decades have been overwhelmed with too much fresh water. Historically, when it rained in a coastal watershed, some of the water would run to the sea and some would sink into the ground. The mixing of fresh and salt water in the right proportions in the estuary creates one of the most productive habitats in the world. Due to Florida's coastal development, much of it involving agriculture, most or our estuaries receive too much fresh water, too quickly, and with too many nutrients. The result-a loss of seagrass and sometimes even fish kills.

For French, who grew up in Palm Beach County, it was the demise of Lake Worth Lagoon during the 1960s and 70s that started him fantasizing about digging a new inlet across the island of Palm Beach to revive the estuary. Not likely.

But in 1999, while working for the Florida Department of Environmental Protection, he heard about a technology called Horizontal Directional Drilling (HDD), a technique often used for drilling a large pipeline beneath a river. That's when it hit him. If you could drill beneath a river, why couldn't you drill beneath a narrow island? Turns out you can.

French's concept was adopted by the engineering firm of Gannett Fleming Inc., and he was hired to promote the idea. (Coincidentally, Gannett Fleming was previously recognized in 1994 for drilling a 48-inch pipeline under the East Elizabeth River in Virginia.)

The T.A.W.E.S. system is designed to bring low-nutrient sea water to places called tidal nodes which are basically the farthest point from an inlet or between two inlets. Water in these areas often doesn't receive the benefits of the water exchange offered by the inlet. Once a system is in place, the salinity is monitored and the optimum amount of sea water is pumped in only when needed, and always during a falling tide so the benefits spread throughout the system.

A similar version of a T.A.W.E.S. began operation near Destin in 1993, to address a problem of fish kills in Old Pass Lagoon. In that instance, the pipe was installed by cutting across the island rather than under. The system brings sea water from a 30-foot depth offshore into the tidal node of the lagoon. Although monitoring of the project has been spotty, no fish kills have been reported since it went into operation.

The need for multiple subsurface inlets in some estuaries, plus the permitting, development, and environmental laws would make it impossible to dig pipelines across most barrier islands, thus the underground drilling comes into play. HDD drilling is limited to about a mile of pipeline, but that's enough to pass beneath any barrier island less than 3,000 feet wide and still have enough line to get out to 20 feet of water offshore. The drilling is done from a barge on the bay side. The pump is then installed in the estuary with a low profile that could even be disguised as a small island. The seawater intake lies below navigation standards and intake speed is not fast enough to imperil fish and other marine animals.

Surprisingly, even the economics of a T.A.W.E.S. project appear solid. The cost establishing one of the long-ranging T.A.W.E.S. pipelines would be about $8 million, with another $60,000 a year needed for operation and maintenance, but the value of a revitalized habitat and the expanded recreational fishing to almost any coastal county, especially urban counties, dwarfs that investment.

In Palm Beach County for instance, the annual resource benefit of seagrass was determined in 1995 to be about $20,500 per acre. The county's rapid growth and concurrent stormwater runoff problems long ago eliminated at least 2,000 acres of seagrass. That's $41 million of lost revenue every year. On the other hand, a large investment up front to install the subsurface inlets necessary to restore the ecosystem would pay off in about five years and then return a steady $41 million per year into the economy.

St. Lucie County is the first local government in Florida to sponsor a T.A.W.E.S. system as part of a restoration project. It's been included in a proposal to the Army Corps of Engineers as one of the alternatives to restoring Blind Creek, a dead-end mangrove creek in the Indian River Lagoon just north of the tidal node between Ft. Pierce and St. Lucie inlets. The creek is routinely the site of major fish kills.

"We're not saying this is the only solution but is part of the overall mix of activities that can be implemented to restore an estuary, rebalance the system, and re-create the biological nursery," said French. Bruce French can be reached at 850-309-7941 (bfrench@gfnet.com).

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