A blog dealing with Sarasota County and the City of Sarasota.

Friday, April 4, 2008

If I were a Commissioner #2: Dredging Big Pass Shoals

The April first edition of the Sarasota Herald-Tribune featured a front page story about six possible strategies for dealing with the incredible accumulation of sand found in what is called the Big Pass shoal south of Lido Key. According to the article, “After four years of study, coastal engineers hired by the county say sand can be mined from one of the coast's biggest shoals without causing Siesta Key homes to slip into the sea or eroding any sand from nearby public beaches.

Pardon my paraphrasing, but the article goes on to say that the County will spend another $200,000 to get three second opinions and seems to suggest that the focus will be on providing reassurance that removing sand from the shoal (for some combination of beach nourishment and channel improvement) will not be likely to have a negative impact on Siesta Key, either by increasing erosion along the pass or somehow affecting the flow of sand to the Key’s beaches.

I like the “first, do no harm” aspect of the county’s approach and therefore support securing those second opinions. But I’m left wondering if there isn’t another side to the equation.

We can compute with some accuracy the value of the sand that might be used to nourish beaches and the savings that might accrue by finding it nearby rather than offshore. And some economist could no doubt take a stab at the value of getting boats in and out of Big Pass more reliably.

But who has been charged with calculating either the present or future value of the shoal as it is or may be in the future? What are those values?

The most obvious one probably will be taken into account and that is how the shoals function to dissipate wave energy. If the shoal didn’t exist the Siesta Key shoreline along Big Pass would be subjected to the full force of the Gulf’s waves. They’ll no doubt look into any potential reduction in that role.

And they will probably consider the potential for the void created by sand removal to intercept sand that might be moving southward – the risk that taking sand ‘upstream’ might starve, or at least reduce the amount of sand ‘downstream’.

But what about Sand Dollar Island – the somewhat ethereal, shape-shifting, seldom-mapped islet that has functioned as both bird hangout and boater destination? Boaters know that the shoal frequently sports supra-tidal sand. And even the sub-tidal portions of the pass area are noted boater destinations as described on the
Sarasota Coastal Watch website.

The value of Sand Dollar Island today is questionable – it probably couldn’t compare with the value of sand that is there more or less for the taking. But might it be worth asking: “Is that it? A tiny, sometimes sandbar? Or might the deck get reshuffled into a winning hand?”

The amount of sand tied up in the shoal south of South Lido is enormous. In fact, that long tongue of sand is actually the submerged portion of South Lido. Without it not only would Siesta’s Big Pass shoreline be under more direct attack, but South Lido as we know it would disappear. For this reason I'm more inclined to the think of the shoal as the southern submerged portion of South Lido.

Put another way, beaches are like icebergs; the emergent part that we notice is supported by a far larger mass upon which it is based. The above-tide sand evident on Sand Dollar Island is a truly miniscule fraction of the sand below the tides. Could some set of storm conditions result in more of the shoal becoming above tide? I don’t know, I’m not a coastal geomorphologist. But I do know comparable events have happened elsewhere with striking results.

Wild and popular Lover’s Key in the Fort Myers Beach area formed
in front of Black Island and Long Key, and the most impressive example locally is probably Johnson Shoals off Cayo Costa. Before that emergent shoal welded onto Cayo Costa it was a boater magnet and important bird habitat as well. Could something remotely comparable emerge on our shoal?  :::shrugs shoulders::: Who knows? But if it ever did the value to local boaters (and birds) would be enormous.

There is probably little percentage in waiting around wondering if some combination of events could lead to a more permanent or more extensive island or islands in Big Pass. 

But before this or future County Commissions vote on any action to deliberately change the shoal it might be prudent to not only consider avoiding future negative impacts to Siesta Key, but also to consider the positive existing (and potential?) values that may be ascribed to both the submerged and emergent shoal.

Our county's past is strewn with projects that seemed like a good idea at the time and now, in retrospect, we're left wondering how our predecessors could have been so reckless. We blithely flattened Indian Mounds for road base, diverted and straightened Cowpen Slough, connected the Myakka River to Robert's Bay and removed unique geologic formations and archaeological treasures from Warm Mineral Springs. Some of these hindsight-inspired errors are irreversible, others are now demanding large sums of money to partially rectify. There is no small measure of humbling irony in the fact that many of today's problems were yesterday's solutions.

Past decisions made about how our coastal areas should be managed and developed are beginning to vex us and in an era of shrinking dollars and expanding expectations we need to be looking for solutions that 'run downhill' -- approaches working in concert with natural systems instead of, as they say, 'bucking the tide'.

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