Monday, September 02, 2019

Summer Haven River: Science and Future Options, by Dr. Michael Shirley, Director, Guana-Tolomato-Matanzas National Estuarine Research Reserve

We need good science to evaluate the 2019 breach of the Summer Haven River Project.  

Here's a paper by Dr. Michael Shirley, Director, Guana-Tolamato-Matanzas National Estuarine Research Reserve, to inform science-based decisions on the misbegotten Summer Haven River Project, now shown to be a failure. 

We in the "reality-based community" will no longer accept the unreal assertions by St. Augustine Port Waterway and Beach District (SAPWB), which has NO staff, only contractors.

SAPWB seems to exist primarily to waste and lavish government funds on no-bid, no-contract contractors like Taylor Engineering, Turnbull Environmental, and sorry mendacious mediocrities, to wit, a no-retainer attorney (JAMES BEDSOLE, a/k/a "BEDSLOW") and no-contract Secretary-Treasurer (ELYSE KEMPER). 

Here is Dr. Shirley's Summer Haven report:

Summer Haven River: Science and Future Options
Current Situation: In 2008, a breach in the dune system carried water and sand that almost entirely filled in the Summer Haven River over the time span of four years.  Surrounding landowners have influenced local decision makers (St. Augustine Port and Waterways Commission) to fund the “restoration” of the river to its 1870’s configuration due to its historic and cultural value.  
My Public Speaking Points:
Point 1:  Estuaries are dynamic systems; they change. At Summer Haven, mudflats and oyster reefs have become sand flats, marsh grass, mangroves and sand dunes.    Nesting shorebirds now use an area that was once under water. From an ecosystem viewpoint, habitats have not become better or worst they have simply changed.
Point 2: The dune breach and subsequent shoaling of the river was caused by both natural and manmade processes. The Changes we are observing are a symptom of a larger set of circumstances that started decades ago.
Point 3: This is a rapidly changing coastline.  In 1569 the Matanzas Inlet was opposite Fort Matanzas there was also once a second inlet where the recent breach occurred (  Maps from 1765 and 1872 indicate the Matanzas inlet moved nearly 4000 feet in 100 years.  
Manmade changes:
  1. 1925: A bridge was placed across the Matanzas inlet and highway A1A was constructed along the oceanfront and the south side of the inlet was hardened. This kept the inlet from moving in its natural southern direction.  

  1. 1932: A channel called the Matanzas Relocation Channel was dug that bypassed a section of the Matanzas River.  This dredged canal redirected tidal flow away from the natural river channel (now know as the Summer Haven River).  

  1. 1945-1951: The by-pass channel was cut to 12 feet deep by 125 widths. A Florida Sea Grant Technical Report (Mehta and Jones 1977) gives a rough estimate of 95% redirection of tidal flow away from the Summer Haven River to the ICW.

  1. 1979 The state abandoned the old stretch of A1A and relocated the road to its present location.

Evidence: Maps dating back to the 1700’s and 1800’s show this stretch of the river (now know as the Summer Haven River) was a much wider and deeper waterway, similar to the rest of the Matanzas River.  (also see Tidal prism estimates from Mehta and Jones 1977). 

Nature has also helped: 
  1. Sea level has been inching up. Estimates Mehta and Jones (1977) provide an approximation of 1.2 inches a decade since 1870 this has been accelerating in recent decades.  Sea level increases caused a landward migration of the shoreline and a steeping of the shoreline profile.

  1. 1964 Hurricane Dora broke through Rattlesnake Island (this island separates the Summer Haven River from the ICW) and widened to 310 feet by 1976 when work was begun to close the breakthrough. Flow to the Summer Haven River was further redirected. Mehta and Jones (1977) estimated tidal flow in the river is approximately 5% of the total coming in the Matanzas Inlet.  
Subsequently, storms have served as a trigger for change.  Our current situation: We have a shoreline that has been eroding and moving inland and, when dune breaches occur, the flow in the river is too slow to clear out the sand.  
Future Options 
  1. Do nothing: Let the area equilibrate to whatever the physical conditions allow.

Pros: Less expensive, marsh and dune vegetation establishes, valuable bird nesting site, beach goers have a new location to enjoy. 

Cons:  Loss of fishing and boating access.  Reduced flow may affect local water quality conditions.

  1. Restore the Summer Haven River to original depths and create oyster reef, mudflat and marsh habitats. 

Pros:  Increased fishing and boating access.   It will look somewhat like it was before. Increased flushing will help mitigate any potential water quality problems.

Cons:  Cost, the project will require continued maintenance with no guarantee of the success. This is likely to increase sediment accumulation in the ICW and destabilize the oceanfront dunes making the area (including A1A) more susceptible to damage by storms. Loss of shorebird habitat and beach access.

  1. Consider a modified Summer Haven River restoration project similar to the oxbow restoration project completed on the Loxahatchee River.  Two sections (north and south portion) of the river, with existing tidal connections, could be reconnected under A1A via culverts or bridges.  
Pros: Mosaic of habitats to be enjoyed by users (boating, fishing, beach goers and nature).  Increase flushing mitigates potential water quality problems.  This would be habitat restoration since A1A is now a barrier to natural flow. It could be suggested as a DOT mitigation project.
Cons:  Cost, especially reconnecting the northern branch. More study is needed to ensure it is self-sustaining and does not adversely affect the ICW, adjacent houses or the dunes.   The system will not be the same as it was before the breach.

Mehta, A.J. and C.P. Jones, "Matanzas Inlet - Glossary of Inlets Report No. 5," Florida Sea Grant Program, May, 1977.



No comments: