Linking lagoon to ocean: Tough, but could help water quality
STORY
City and county officials are intrigued with the idea of opening an inlet of some kind between the Indian River Lagoon and the Atlantic Ocean to improve water quality and ecosystem health in the estuary, but they also are cautious about cost and possible permit challenges.
“The idea may have merit, based on what I have seen,” says Vero Beach Public Works Director Monte Falls. “I think it is a concept that deserves further study.”
County Commissioner Wesley Davis says he would support the idea “in a heartbeat” if research shows it would be beneficial and if permitting agencies are on board. “It would be ridiculous for the county to spend a lot of time and money planning something like that if the Army Corps is going to fight it.”
The idea of a lagoon/Atlantic link surfaced last fall when island attorney Nick Thomas championed the proposal in his unsuccessful campaign for the District 5 county commission seat.
There are three basic versions of the idea: An actual inlet like the Sebastian and Fort Pierce inlets; a large culvert or series of culverts with pumps to move fresh seawater into the relatively stagnant lagoon; and a pipe or series of pipes without pumps that would allow water exchange powered by tidal action, with water flowing into the lagoon when the tide rises and back out when the tide falls.
The first version is a non-starter by most accounts.
Making an actual break in the barrier island that boats as well as water could move in and out of would be too environmentally traumatic, interfering with the natural migration of sand along the coast, impacting large amounts of private property and requiring permits from every state and federal environmental agency in existence.
“That would be a very large change to the lagoon and the coast,” says Chris Mora, county public works director. “I can think of a million questions that would have to be answered before beginning to consider something of that nature, including the cost, how deep it would be, who would be responsible for keeping it dredged and how it would affect the coast.”
Michael Walther, president of Coastal Tech, a consulting firm that specializes in coastal engineering and environmental permitting services, said at the recent county lagoon symposium that the “cost, [construction] difficulty and permitting issues may make it impossible to create an actual inlet.”
A culvert connection seems much more doable in financial and engineering terms. There is a promising location for a pipe from the ocean to Bethel Creek at Jaycee Park, where the city owns the narrow strip of land between the lagoon and the ocean, and it is a proven technology that has restored eco-health to several bays and harbors around the country, including Destin Harbor in the Panhandle.
Before a culvert and pump were installed in the early 1990s, Destin Harbor suffered from many of the same problems that plague the Indian River Lagoon, with low oxygen, high algae growth and marine animals dying as pollution from runoff and multiple marinas degraded water quality.
“There were a bunch of fish kills in the lagoon back in the 1980s,” says David Bazylak, Destin’s harbor master and environmental control officer. “There is only a small harbor outlet and tidal fluctuation is low so there wasn’t a lot of flushing. We had a bad problem in summer with low dissolved oxygen.”
Destin’s response, strongly supported by residents, was to install a pump at the narrowest point on the peninsula that encloses the harbor and hook it up to a concrete culvert seven feet in diameter that extends 970 feet out into the Gulf of Mexico.
The pipe, which is buried beneath the sea floor, terminates in a chimney-like intake structure that rises 15 feet above the sandy bottom in 35 feet of water. The pump sucks 50,000 gallons of seawater per minute into the pipe and discharges it into the lagoon, forcing stagnant water out the narrow mouth of the harbor.
The city runs the pump six or seven hours per night, seven nights a week, from April to October, at a cost of about $3,000 per month, according to Bazylak.
“It has worked really well,” he says. “The pump went into regular operation in 1993 and we haven’t had any major fish kills since then, other than those caused by red tide. Water clarity and testing results have been good.”
A culvert without a pump that exchanges water through tidal action has had a similar positive effect in the town of Truro, Mass., on Cape Cod, helping to restore a 740-acre estuary that was being smothered by low oxygen and algae blooms.
According to an annual report on the project, “the clapper valves in the four-foot diameter by 700-foot-long culvert connecting the East Harbor Lagoon to Cape Cod Bay have been held open since Nov. 2002 . . . . Despite limits on tidal exchange imposed by the pipe’s small diameter, and the distance that it travels underground, we have observed an impressive response in the recovery” of water quality and marine animal health and abundance.
The problem of stagnation that motivated culvert projects in Destin Harbor and East Harbor Lagoon is shared by the Indian River Lagoon.
The lagoon runs 15 miles from the Barber Bridge to the Sebastian Inlet and about the same distance to the Fort Pierce inlet, and pollution that pours into the estuary in Vero Beach from fertilizer-laden runoff and septic tank seepage lingers because of the low water exchange between the lagoon and the ocean.
But there is also a big difference between the Indian River Lagoon and the estuaries in Destin and Truro: The lagoon is much larger.
The 50,000 gallons per minute of seawater that purifies Destin Harbor would not begin to flush the entire lagoon between Vero and Sebastian, the stretch of water where the estuary is most degraded.
Nick Thomas admits the difference in scale is huge but says local improvements could be achieved. “If we clean up the area by the bridge and marina we could start what I call a virtuous cycle. As the water quality in that area improves, seagrass and mollusk populations would be restored. The mollusks would then extend the cleaning process by filtering the water.”
Dr. Richard Baker, University of Florida biology professor emeritus and president of the Pelican Island Audubon Society, is skeptical of engineered solutions to environmental problems. “These kinds of engineering ideas have caused us much grief in Florida in the past.”
Baker questions the wisdom of sending polluted water out into the Atlantic, which has its own ecological challenges, and says the emphasis should be on stopping the sources of pollution. He says the county and state should limit fertilizer use and mandate the replacement of outdated septic tank systems that leak into groundwater and the lagoon.
Ecologist David Cox shares Baker’s skepticism about engineered solutions. He says a culvert “might be beneficial,” but that that any plan needs to be thoroughly researched. “Somebody would have to do computer modeling to see what the area of impact would be.”
He also cautions against unintended consequences. “Engineering solutions tend to happen fast once they are decided on, but nature reacts slowly, so it would be a while before the impact would be clear.”
Vero Beach City Council member Pilar Turner, who is an engineer as well as a politician, says an engineering study would have to be the first step. “A study to determine the cost and look at potential consequences such as scouring [in Bethel Creek] and changes in lagoon salinity would be essential.”
Falls says he too has questions and concerns about the design of a culvert but still believes “the idea deserves to be looked at. Anything that seems reasonable and that might benefit the lagoon should be evaluated.”
