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Local Government Manatee BOCC Navigates Longboat Pass


BRADENTON -- Natural Resources Department Director, Charlie Hunsicker, started his presentation at Tuesday's BOCC workshop saying, "A waterway separated by two governments, will be shared by two governments." He later reiterated, "what has separated us, will bring us together." Hunsicker was talking about the narrowing channel, an inlet waterway that separates Anna Maria Island and Longboat Key, known as the Longboat Pass Inlet. 

The project, is an effort to bring joint management of Longboat Pass for navigation, beach nourishment and coastal protection. To qualify for the funding, the project must be supported by separately approved inlet management plans. Both governments, Manatee County and the Town Of Longboat Key, entertained recommendations to mitigate the current erosive effects of the migrating channel.

The channel has been moving south, closer to the Longboat's shore, eroding beach from some areas and displacing it elsewhere. Consequently, the tidal movements have been eating away valuable real estate, more on the south (Longboat), than north, at Coquina Beach. 

The workshop was a meeting between both governments to review findings by the Army Corp of Engineers (ACOE), Florida Department of Environmental Protection (FDEP), West Coast Inland Navigation District (WCIND), and other contracted firms, to develop and Inlet Management Plan.

Hunsicker introduced Millan Moran, PE, ACOE. He described the method by which the sand would be dredged up using a hopper dredge named "Murden". This vessel separates, strait through from bow to stern, then closes, carries the sand cargo to another location and disperses it. It is truly a unique ship. Then Moran explained, how by qualifying for funded ACOE operations, millions of dollars will be saved by both governments.

Next was Coastal Planning & Engineering Inc (CPE) Executive Director Rick Spadoni, and Senior Coastal Engineer, Thomas P. Pierro P.E., D.CE, who gave a stellar presentation. Armed with 10 alternative models, evaluations of each design and time lapse graphics, they wooed the room. Ironically, the number one on the list was "no action," other than dredging to correct the channel that was migrating southward.

Most of the models located "groins" or barriers that would alter the current, redirecting the sand movement and somewhat protecting the erosion. Each model, with different size groins, would distribute the sand differently. The groins could be moved, extended or removed, but all methods had some consequences and expense. 

The two governments have been redistributing dredged sand, sharing it 50/50, to reconstruct eroded areas for years, but it recedes within a year and sometimes in only a matter of months. Many of the residents say the sand is disappearing more rapidly, and the models suggest why. 

The more the channel changes, the bigger bite of beach it will continue to take. The groins will help that, but so will the dredging the channel. Both operations have everything to do with how the erosion will change the shore. The way in which the channel is dredged and the approach to it may slow or even reverse some of the erosion, eliminating much of the panic land owners are having. I am reminded, every action has a reaction.

Some of the reactions to the groins are; interrupting in manatee (sea cows) migration and compromising navigation. There is always the expense and the unintended consequences. Commissioner Joe McClash brought these points up in favor of leaving as much natural as possible. He said, "the natural option should be number one on the list... what's the rush."

CPE recommended a plan, with four recommendations:

1 - Extend a jetty at Coquina Beach. (approx. $4,250,000)

2 - Construct a new jetty on north side of Longboat Key (approx.$4,250,000)

3 - Construct two perpendicular groins on north end of Longboat Key (approx. $1,500,000)

4 - Periodic maintenance dredging of Longboat Pass at four to six year intervals to maintain the navigation channel (approx. $500,000. with each maintenance). Each dredge would create 100,000 cubic yards of beach compatible sand.

The Delft3D modeling of tides, flow, waves, sediment, transport patterns and bathymetric evolution, used by CPE, sure gave everyone a lot to think about. Often, where the most unintended consequences occur is when we try and change nature. When I said that, Spadoni and Pierro agreed, adding, that is how this problem occurred in the first place. If anybody knows, they do. Everyone there was amazed with the scope of their in-depth presentation.

The next workshop on this matter will be March 13. Meanwhile, everyone involved has a lot of homework to do. 


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