Dr. Richard Hilderman: Essays on Dredging

Understanding The Issue of Dredging

Naturally Occurring Waterways

The Dredging of Jink’s Creek: Article One

 

Since 2016 the Town of Sunset Beach has been working on developing a potential dredging project.  This project includes the dredging of Mary’s/Turtle Creeks, Canal Bay Area, the feeder/finger canals along with Jinks Creek.  There is an ongoing controversy surrounding this project not only by the citizens but also by council members.   There are no concerns with the dredging of Mary’s/Turtle Creeks, Canal Bay Area and the feeder/finger canals because this is maintenance (from previous) dredging to keep these areas open for shallow water boats.  However, there a several concerns regarding the dredging of Jinks Creek.  In the next several weeks I plan to write short articles outlining these concerns.  Hopefully, this information will help you decide whether or not it is appropriate to dredge Jinks Creek.  If you don’t want to get further emails on this subject please let me know and I will delete your name.  If you know people who may be interested in receiving this information please send me their email address. 

One of the concerns regarding the dredging of Jinks Creek is will the creation of a 60 to 80 foot wide and 6 foot below mean low tide navigational highway, through the entire length of Jinks Creek, increase the risk of erosion and flooding during storm surges on the east end of the island?  After a storm, all that surge water must get back to the Atlantic Ocean.  Matthews is an example of this type of flooding and erosion.  Moffatt and Nichols, the engineering firmed hired by the Town, using computer modeling says there will be no increase risk.  Scientists using the same computer model predict that the water volume through the channel will increase by 40% with an accompanying increase in velocity. 

The Town has been working with a Scoping Committee on the dredging project.  This Scoping Committee includes of Division of Coastal Management, State and Federal agency scientists and the US Core of Engineers.  The primary purpose of this committee is to make recommendations to the Town regarding the dredging project.  Scoping Committee members estimate 310 houses will be impacted by the creation of this navigational highway through Jinks Creek and they recommend that an environmental impact study (EIS) be performed.  Do the property owners on the east end of the island have a right to request an EIS in order to determine whether their property will be impacted?

 

Richard Hilderman, Ph.D.

 

 

The Dredging of Jink’s Creek: Article Two

 

This is the second in a series of concerns regarding the dredging of North Jinks Creek (feeder canal north to the Intracoastal Waterway).  The destruction of oyster beds.  Remembering that Jinks Creek is a naturally occurring tidal creek, CAMA regulations state that dredged channels must be aligned to avoid shellfish beds.  North Jinks Creek has a high density of oyster beds with the density increasing towards the Intracoastal Waterway.  Oysters are important filter feeders which remove contaminates from the water.

The Scoping Committee requested the Town to fund an oyster survey to determine the density and location of the North Jinks Creek oyster beds.  The cost of this survey was $90,000. Reviewing the results of this survey, the Scoping Committee  estimated 13,000 oysters will be destroyed by dredging North Jinks Creek. If the Town decides to proceed with dredging of North Jinks Creek, it will require oyster mitigation.  It is my understanding that each acre of oysters destroyed will require a new acre of mitigation to comply.  Mitigation requires “planting” oysters in a new location.  In addition, the Town will have to fund a 3 to 5 year evaluation study to determine if the mitigation was successful. If the mitigation proves to be unsuccessful, the Town may be required to perform additional mitigations. This is a long, detailed process.  There may be physical and/or biological reasons why the chosen mitigation sites are void of oysters.  What is the success rate of this type of mitigation?  What is the overall cost of this mitigation project?

 

Richard Hilderman, Ph.D.

 

The Dredging of Jink’s Creek: Article Three

 

A third concern regarding the dredging of Jinks Creek is the relationship of Jinks Creek to the surrounding primary nursery areas (PNAs).  CAMA regulations prohibit dredging in PNAs.  Seventy five percent of the seafood we eat spend at least part of their life cycle in the PNAs.  Thus, the PNAs are not only a vital food source but are also important for the economy of  coastal North Carolina’s fishery industry.  Jinks Creek has been designated a non-PNA.  The first attachment is a map showing the PNA areas of both SSB and OIB.  This map clearly shows (in red) all the marshes and tidal creeks around SSB that have been designated as PNAs.  The only exception is Jinks Creek.

It appears Jinks Creek was deemed a non- PNA in the 1970s only by default.  The relevant data generated for Jinks Creek are from a single survey conducted in 1971; apparently this single one-month survey did not generate sufficient data to merit a written report.  Obviously, a primary nursery area (PNA) could not have been designated on the basis of these data nor could such a designation be ruled out (two attached emails from Pat Smith). Jinks Creek is completely surrounded by PNAs and is the connection between the PNAs and the Atlantic Ocean, Tubbs Inlet and the Intracoastal Waterway.  The Creek provides for a flow of nutrients to the PNAs and a pathway for juveniles to move to other areas.

 

At the 2/20/18 council meeting Mr. Corbett, asked Mr. Neal of Moffatt and Nichols if dredging of Jinks Creek would have an impact on the surrounding PNAs.  Mr. Neal simply said no without giving a justification or explanation.  I thought it important to discuss Mr. Corbett’s question with a scientist who has the appropriate expertise to address the question.  Dr. Steven Ross is one of the foremost estuary-dependent fin-fish experts in the US.  In the late 1970s, Dr. Ross was a member of a committee to reevaluate the scientific data for PNA designations in coastal North Carolina. 

Dr. Ross’s comments:

1.     Dredging of Jinks Creek will have an impact because it will cause the creek to go from a natural environment to an unnatural environment

2.      Dredging of Jinks Creek will change the depth and velocity of the water in Jinks Creek.  This will change the transport of water, nutrients, and various animal species into the PNAs.  The overall impact on the PNAs is not known.

3.     Dredging of Jinks Creek will increase shoreline erosion.  The tidal current will carry some of this sediment into the PNAs where it will be deposited.  Overall impact is not known.

4.     Dredging of Jinks Creek will destroy oyster beds.  Since oysters are filter feeders, this will impact the water quality.

5.     Dredging of Jinks Creek will impact the habitat of several species of fish.  Several species of small fish use oyster beds as a habitat for predator protection.

Dr. Fritz Rohde, a NOAA scientists and member of the Scoping Committee selected to advise the Town about the dredging project, believes Jinks Creek is a functional PNA.  Dr. Rohde worked 25 years for Marine Fisheries where he was involved in sampling various areas of Brunswick County including Jinks Creek.  His sampling data of Jinks Creek showed a comparable level of diversity in different species of fish, shrimps and crabs to the diversity of areas that have been designated PNAs.  This makes sense.  Jinks Creek and the surrounding PNAs are elaborately interconnected throughout the entire length of North Jinks Creek and the animal species can move freely between the two areas.

 

What impact will the dredging of Jinks Creek have on the PNAs?

 

Richard Hilderman, Ph.D.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Dredging of Jinks Creek: Article 4

Another concern regarding the dredging of Jinks Creek is the need for repeated maintenance dredging.  Jinks Creek is a naturally occurring shallow water tidal creek.  Except for a small part of the creek adjacent to Tubbs Inlet and the Canal Bay area, it has never been dredged. Maintenance dredging is a term that refers to the protocol necessary to “maintain” once a canal, channel or creek has been dredged.  Property owners on the finger canals are familiar with maintenance dredging.  As Dr. Ross pointed out in Article III, dredging of Jinks Creek will impact the entire area because it will convert the creek from a natural environment, to an unnatural environment and a potentially unbalanced system. 

One of the impacts will be the need for repeated maintenance dredging to keep the navigational channel open.  Silt build up can be expected from the Atlantic Ocean, the Intracoastal Waterway, and the sides of the dredged channel.  The amount and timing of maintenance dredging will depend on such factors as sea-level rise, tides,  frequency and severity of storms, and the amount of speed boat traffic.  Most people who have the appropriate expertise, predict it will be needed every 3 to 5 years.

What will be the costs of the periodic dredging?  Who should pay for the dredging?  Is it reasonable that all SSB taxpayers (residents and non-residents) pay for this perpetual maintenance dredging? Or should the property owners on the feeder/finger canals and Canal Bay area that will directly benefit pay or it?

 

Richard Hilderman, Ph.D.

 

 

The Dredging of Jinks Creek: Article 5

 

Another concern is the cost of the dredging project.  In February, Mr. Neal of Moffatt and Nichols estimated the Town’s share was $1,058,808.88.  He also estimated the cost for each of the 350 properties in the project area would be $3,025.  However, this estimate doesn’t included oyster mitigations (Article II), repeated maintenance dredging (Article IV), nor potential costs of spoils disposal, or a potential Environmental Impact Study or an Environmental Assessment which may be required for the federal 404 permit.

Before dredging North Jinks Creek, we should all consider a simple and fundamental question.  Is dredging worth the monetary cost and the potential environmental impact it will trigger in both North Jinks Creek and the surrounding PNAs (Article III and Dr. Pietrafesa’s Article) so larger boats can use North Jinks Creek at low tide?

 

Richard Hilderman, Ph.D.

 

 

The Dredging of Jinks Creek: Article 6

 

Another issue the Council needs to address before approving any part of the dredging project is who will pay for the dredging costs after the initial project costs?  Property owners directly impacted by the dredging (waterfront property owners in the dredging areas) or all Sunset Beach taxpayers?  Even the issue of who will pay for initial dredging costs is not clear.

Initial dredging project costs:

At the July 2 council meeting, the council approved unanimously the following motion from Councilwoman Harris:  “In order to avoid further delays to the maintenance dredging of the existing canals, bay and South Jinks Creek, I move to assess 100% of the costs (excluding grant money) for the "maintenance dredging project" [to] ONLY "those properties with frontage abutting on the project" using method (1) of NCGS 160A-238, which states "Assessments for these projects may be made on the basis of:  (1)  The frontage abutting on the project, at an equal rate per foot of frontage,"  This part of the project has been "approved" by Council at least to the extent that M&N has been directed to proceed with the permitting process.

1.     The affected property owners have a right to know if Harris’s motion includes the full cost of placement of contaminated spoils from the canals and the cost of non-contaminated spoils on Sunset Beach.  The costs for non-contaminated spoils are missing from the “construction costs” slide in Moffatt and Nichol’s 2/20/18 presentation to the Council.  A 9/5/17 cost estimate under “Dredge and Fill” lists $68,660 for compatible material.  Is this no longer a cost?  The 2/20/18 slide is the basis for the often repeated $3,025 per “household” cost of the initial dredging project (Article V).

2.     Councilwoman Harris has pointed out that dredging of the finger canals may require the removal and replacement of docks and/or piers. Property owners would be responsible for removal and replacement costs.  What will those costs be? 

3.     Furthermore, who will be assessed for the costs for the maintenance dredging of Mary’s and Turtle Creeks?  

 

The initial dredging costs addressed by Councilwoman Harris’s motion are only a part of what this project might ultimately cost.

Possible future dredging project costs:

 

It has not been determined who will pay for repeated future maintenance dredging (Article IV).

Shouldn’t the Council not only estimate the total cost of the entire dredging project but also clearly indicate who will be responsible for these costs before any permit is applied for?

Richard Hilderman, Ph.D.

The Dredging of Jinks Creek: Article 7

In August 2016 the SSB Town Council created the Environmental Resource Committee (ERC).  The committee members were Neil Gilbert, Jan Harris, Richard Hilderman, Gary Merritt and Sandy Payne.  The Council’s initial charge was for the committee to do the necessary research on the shoreline dredging project and make recommendations to the Council.  The committee sent their recommendations to the Council in January, 2017.  The Council voted 3 (Corbett, Larkin and Scott) to 2 (Benton and Cerrato) not to accept the report.

Attached is a copy of the ERC report.  It is important to point out that the ERC raised concerns about the oyster density in North Jinks Creek.  The Scoping Committee agreed and requested the Town perform an oyster survey.  The results of the survey suggested an estimated 13,000 oysters would be destroyed by the dredging and the committee recommended oyster mitigation (Article II) if North Jinks Creek was to be dredged.

 

Richard Hilderman, Ph.D.

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