Posted on February 10, 2020
I am a professional geologist who has worked on coastal zone management issues for more than 35 years. So what if I said I could construct a new inlet connecting the Indian River Lagoon to the Atlantic Ocean that would restore water quality, mitigate risk of algal blooms, red tides, storm surge and sea level rise, protect against erosion, create a world class surf break and prime fishing grounds, generate hydropower, and enhance national security at no cost to the local tax payer?
Would you support the idea?
Of course you would (who wouldn’t?), and a petition proposing a new inlet on the north-end of Patrick Air Force Base as garnered nearly 10,000 signatures so far.
The problem is it can’t be done.
More importantly, elixirs like this one distract us from the real cause of the lagoon’s demise: the massive influx of nutrients (nitrogen and phosphorus) from surface water, septic, and water treatment plants that have accompanied urban growth over generations.
More on that later; let’s first review a few of the a new inlet’s enticing elements.
Water quality restoration
The influx of sea water into the lagoon via a new inlet doesn’t restore its water quality. It changes it from estuarine to marine. In the process, it dilutes nutrient loads during the flooding tide as seawater mixes with lagoon water and exports the polluted mixture into the Atlantic Ocean during outgoing tides. Over time, ecosystems and habitats historically present in this part of the lagoon and adjacent Atlantic Ocean coastal waters will be replaced by those that can tolerate more salt and less pollutants (lagoon) or less salt and more pollutants (ocean).
The extent of these changes can’t be foreseen with certainty, but one thing is clear; the new mix of plants and animals won’t look anything like what is there now. All of this assumes there will be enough tidal pumping to ensure the requisite mixing occurs at a scale and level of intensity to significantly impact the lagoon’s water quality. That seems doubtful given the tides are small and the geomorphology obstructive and constricting.
Storm surge
The construction of a new inlet will not reduce the risk of flooding during landfall of storm events. Quite the opposite is true.
A new inlet will provide an opening in the barrier island through which surging storm water will flow into the lagoon. This will occur well in advance of flood waters that would otherwise eventually overtop the barrier island’s beaches and dunes.
Sea level rise and national security
Construction of the inlet will have no mitigating effect on future sea level rise. Hence, the risk of future flooding at Patrick Air Force Base will not be reduced by inlet construction, nor will related national security benefits be realized as described in the petition.
Erosion protection
Barrier island inlets do not mitigate coastal erosion, they cause it. Once constructed, these features create instability along nearby shorelines and seabed. This then requires an expensive suite of shore protection projects that must be constructed and maintained in perpetuity.
Hydropower
Initially, the petition states the site for the new inlet was selected at a location with minimal tidal range to avoid shoreline and seabed erosion. And while the rationale of this argument is flawed, so too is the notion of generating hydropower at a presumably narrow and shallow opening where the tidal range is small.
Cost
The petition suggests all the costs to construct and maintain the new inlet could be paid for by the U.S. Army Corps of Engineers. But Corps involvement with inlet management is predicated on the feature being classified as “navigable.” The design features and requirements of a new navigable inlet are very different than a non-navigable one and likely detrimental to the petition’s objectives.
That said, the creators of this petition should be acknowledged for their commitment to improving the water quality of the Indian River Lagoon. And they have clearly been thinking outside of the box, which is a better approach than business as usual.
However, we cannot lose sight of the real antagonist; nitrogen and phosphorus. The only practical, realistic, and viable means of improving water quality is source reduction; reducing nutrient input from surface water conveyance systems, septic tanks, and wastewater treatment plants. That said, we must be mindful the necessary upgrades and new construction will take decades to complete and cost billions of dollars.
Now is the time for all us living within the lagoon watershed and beyond to recognize nutrients are the culprit and to support mitigation actions designed specifically to reduce or eliminate their input.
Randall W. Parkinson, Ph.D., is a research associate professor at Florida International University’s Institute of Environment. He lives in Melbourne.
Source: floridatoday.com
