Tuesday, June 15, 2021

What Exactly is Tide-Leveling?


Photos by Maria Lamb  | (L – R) Representative Lauren Melo of Florida District 80, Representative Bob Rommel, Florida District 106, and Senator Kathleen Passidomo.


The Collier County Legislative Delegation met at the North Collier Regional Park on Friday, December 4th. Marco Island City Council Chair, Jared Grifonipresented two legislative priorities for Marco Island:  

  1. The San Marco Tide Leveling Project.  
  2. A request for a sovereign immunity policy decision.  

According to Councilor Grifoni, tide leveling and canal flushing is an integral part of the City of Marco Island’s Master Plan for water pollution control. The project will install dual 48-inch culverts as well as inlet structures between the two basins under the San Marco roadway and through existing easements. Total cost is estimated to be $750,000 with $325,000 provided by the City of Marco and $425,000 provided by a State grant.  

The proposed construction site is located between two vacant lots on San Marco Road to the immediate West of the Copperfield Court and San Marco Road intersection. This site is to the east of the San Marco Catholic Church.  

Manatee gates would need to be installed to prevent this species from entering the culvert.  

Benefits mentioned in the local funding initiative request for this project were: reduction of nitrogen, reduction of phosphorus, increased oxygen levels, and elimination of street flooding.  

Two visual inspections of the proposed construction location were completed on December 4, 2020, one at low tide and then again at high tide by Eugene Wordehoff, a local resident and engineer, along with this author.

 



 

The first set of observations was at Noon, Friday, December 4, 2020. On the South side of San Marco Road at the canal wall, there was no floating debris observed and the water was clear enough to see the bottom. The canal waters were calm. On the North side of San Marco Road, at the canal wall, there was no debris and the water was clear enough to see the bottom with calm canal waters as well.  

Marco Island Councilor and Chair of City Council Jared Grifoni.

The second set of observations was at 5 PM, Friday, December 4, 2020. On the South side of San Marco Road at the canal wall, there was no debris of any kind and the water was clear enough to see the bottom. The water level was 28 inches below the top of the seawall with calm canal waters. On the North side of San Marco Road at the canal, there was no debris and the water was clear enough to see the bottom with calm canal waters. The water level was also 28 inches below the top of the seawall. The 5 PM tide was not a King Tide, however, there was no flooding observed.  

The water was clear and there was no debris observed in the water. There are no reports of low oxygen levels or high phosphorus levels on Marco Island as per the Turrell, Hall & Associates report entitled “Summary of Nitrogen Levels in and around Marco Island Waters” dated February 2019. This is available to the public on the Marco City Web Site.  

Mr. Wordehoff, a resident of 20 years, commented he has never personally seen tidal flooding on San Marco Road. The fact that the water levels were the same on both canals implies that there would have actually been no flushing action at the time of this observation. The effectiveness of culverts to stem the tide is debatable.  

Demonstrated needs in the form of a Flushing Study for the waters around Marco Island may prove to be useful if this project is to move forward. A specific connection between tidal flushing and a reduction in nitrogen would have to be established. Marco’s only water impairment is for Total Nitrogen (TN). The 2019 level was found to be 0.63 mg/L which is above the standard of 0.3 mg/L. 

 


 

One response to “What Exactly is Tide-Leveling?”

  1. Eugene Wordehoff says:

    A survey of all of the Marco Island canals might be a useful starting point for improving area waters.

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