The Levees at Mutton Cove

I visited Mutton Cove today where I became intrigued about when and how the levees at the site were built. I had noticed that the rocks for the outer levee bank had been reinforced with iron rods and heavier iron reinforcing had been used in areas of heavy tidal flow. I decided to take lots of photographs of the levee and the reinforcing, much of which has now become exposed and broken away.

All of my photos from the visit can be found at https://1drv.ms/f/c/f49cda2ca5c2599b/Es5Sn_3L9CxHlrIvz90Dy1IBYhjuNNQJYlZIuwiT8YS-gQ?e=mBHaeo .

Half the reason for my visit to Mutton Cove was to check on the location of my 2018 discovery of what appeared to be a large anchor buried in the levee.

The State’s Maritime Archaeologist of the time re-buried the anchor.

I was unable to re-locate the item during my recent visit though.

It seems that the levees at Mutton Cove at Pelican Point in South Australia were built in the 1970s. According to Coastal carbon opportunities: vegetation dynamics at Mutton Cove, a site of recent tidal reconnection SUMMARY REPORT by Alice R. Jones, Ramesh Raja-Segaran, Dillon Campbell, Milena Fernandes, Michelle Waycott, Paul Lavery, Oscar Serrano, Anna Lafratta, Bronwyn M. Gillanders, “the seawall (around Mutton Cove) was built around the site in the (early to) late 1970s”. Such comments are repeated three times.

According to the paper titled “Environmental Management Plan Mutton Cove, South Australia” by Peri Coleman, the middle photo on page 16 indicates that “new land that was being reclaimed” on the eastern side of the Lefevre Peninsula “for the Outer Harbor port facilities, and the beginning of the sand accumulation near the training walls that would ultimately become the suburb of North Haven.”

“By the 1970’s land accumulation was proceeding apace, with dredging and waste disposal occurring in bunded blocks across the entire Pelican Point area. Mutton Cove’s bunding is also evident (in the middle photo), and it is likely that filling was probably the fate envisaged for the Cove also, at that time.”

I asked the Microsoft Copilot AI Assistant, “How was the levee at Mutton Cove, Pelican Point SA built?”

The response was, “The levee at Mutton Cove was originally constructed as a seawall to protect the saltmarsh and surrounding infrastructure, but its exact construction method isn't well documented publicly. It likely involved compacted earth and rubble, typical of older levee designs in industrial coastal zones.”

Further, “Here's what we know about its history and structure:

Construction and Purpose

•             The levee was built to shield Mutton Cove’s saltmarsh from tidal inundation, supporting both environmental conservation and industrial land use at Pelican Point.

•             While detailed engineering records aren't readily available, local accounts and environmental reports suggest it was a simple earthen embankment, possibly reinforced with rubble or concrete in sections. This was common practice for levees built in South Australia’s industrial zones during the mid-20th century.

Breach and Transformation

•             In May 2016, the first major breach occurred in the seawall, leading to flooding of the saltmarsh and rapid mangrove colonization.

•             The banks on the north, west, and south sides of Mutton Cove were not formal seawalls, and have continued to erode over time.

•             Since the breach, the area has transformed into a mangrove forest, and restoration efforts have focused more on stabilizing natural boundaries than rebuilding the original levee.

Restoration and Living Shoreline Concept

•             A “Living Shoreline” design was proposed by Peri Coleman of Delta Environmental to replace or supplement the damaged levee. This approach emphasizes natural stabilization using vegetation and ecological buffers rather than hard infrastructure.

•             Funding and planning have involved groups like Australian Naval Infrastructure, Flinders Ports, and Green Adelaide, but as of late 2023, no full restoration has been completed.”

I then asked the Assistant, “Do you know the construction date of the levee?” The response was, “The exact construction date of the Mutton Cove levee at Pelican Point, SA is not publicly documented, but it likely predates the 2010–2013 Northern Lefevre Open Space redevelopment. It may have been built in the mid-to-late 20th century as part of industrial land protection efforts.”

Further, “it was possibly (built) in the 1960s–1980s, when Pelican Point’s industrial and port infrastructure was expanding.”