The current extensive mudflats in North Arm Cove are a recent phenomena. The earliest mention that I have found about the North Arm Cove shoreline is an article about Halloran’s Port Stephen City in the Armidale Chronicle in June 1920. “No mudflats mar the shore of this estate, this future city-no expensive reclamation, no long jetties.” This article may have only been talking about the rocky shoreline south from Point Circuit, or it may have been the entire shoreline.
Many of the Cove’s older residents recalled sand in the mid 1900’s. We have a photo of the shoreline taken looking north from about 90 Cove Boulevard in 1975. It shows a shoreline covered in derelict oyster leases and even the remnants of older leases coming out from the shoreline at 90 degrees. There was no sand in this area. The first oyster leases were in 1885. By the middle of the 1900’s, oyster leases covered most of the shoreline.
We first came to the Cove in 1987. At that stage, it was still sandy off Water Street and Merriwa Boulevard. Cars used to drive out on the sand at Water Street to launch their boats. It took only one season around 2000 for the sand to turn to mud.
So what caused the mudflats? I think it was a combination of factors, but without a source of silt, the problem does not occur.
The problem probably started In the 1920’s with Henry Halloran. Halloran cleared extensive areas around the shoreline for his land sales. Then in the late 1970’s, developers put tracks through the nonurban area. They surveyed the tracks, removed the trees and brought in fill to level the tracks. The tracks are now heavily eroded and the fill has mostly been washed down into the Cove.
A second cause would have been upstream clearing for agriculture, roads and housing. The fine sediment gets washed down the waterways in heavy rain and deposited in the Cove, especially around oyster leases, which are a major cause of siltation.
Oyster farming started in the late 1800’s but did not really get going until the mid-1900’s. Upstream clearing and Halloran’s clearing would have provided a good source of fine material. In areas with oyster leases, water velocities decrease and finer material gets deposited. In addition, oysters excrete waste which also gets deposited. Many old leases have derelict posts that are buried in mud. Originally the oyster leases were against the shoreline and the racks came out at 90 degrees to the shoreline. When the racks became covered in silt, the leases were moved further from the shore to deeper water. In 1975, the Colvins, took many photos of the oyster leases and they campaigned for their removal based on the environmental damage from siltation that was occurring around the oyster leases- see attached letter.
The third source of silt would have been the construction of the village from the mid 1900’s. Trees were removed, houses were built on steep blocks and eventually soil was washed into the waterway. In some areas along Cove Boulevard and Eastslope Way, the shoreline was eroded by several metres, further adding to the silt load in the water. These days, we use silt fences to try to stop silt getting into the waterways, but this was not always the case and nor is it always successful. The loss of sand at Water St is an example and was probably caused by stormwater runoff down the drainage system next to Water St.
The end result of all this human activity is a muddy shoreline. In recent years the oyster racks and posts were replaced with floating baskets. After Covid, some of the floating baskets were removed but have now been replaced again. We were getting some sandy banks developing in the mudflats. Perhaps, over time without the floating baskets, the shoreline would gradually repair itself. The major risk now is the extensive land clearing without any siltation controls going on in the nonurban area.
