Manning Valley Region
Acid Sulphate Soils
33,797 hectares of land within the Manning Valley has been identified as being affected by potential acid sulfate soils (ASS). 4,500 hectares has been identified as ASS hot spots by the NSW Government.
ASS are sediments naturally occurring in estuarine and floodplain areas, which were once high in organic matter (such as old mangrove forests and other wetlands).
These sediments occur below the water table and when left in place are not a problem. When removed from a waterlogged state, such as during excavation or as a result of drainage (lowering the water table), these sediments oxidise and the passage of water through the material creates acid run-off or leachate that can contaminate surface and ground water.
In addition to the acid nature of the water, it also carries increased levels of aluminium and other metals, which can be toxic to aquatic flora and fauna and those species living in bottom sediments. The impact on fish stocks and oyster production can be significant.
We have undertaken a very successful ASS restoration project at Cattai Wetlands and have begun another restoration project at Big Swamp.
For those wanting to develop land that may be affected by ASS and require planning advice, we have prepared a fact sheet(PDF, 62KB) to help you.
For more information about ASS visit the NSW Primary Industries website.
Our beautiful Manning River and its tributaries have long been havens used by visitors, holiday makers, locals, oyster farmers and anglers.
The Manning River is one of only two deltas in the southern hemisphere with two river entrances, the main entrance at Harrington and the second at Farquhar Inlet, just south of Old Bar. The Manning River is a complex estuarine system which includes a number of branch creeks and channels.
There are a number of public ramps, wharves, pontoons, riverside parks, commercial tourist destinations and towns and villages scattered along the river.
The following documents have been prepared to guide the management of the Manning River estuary:
Farquhar Inlet entrance opening management plan
The Farquhar Inlet is situated at what is considered to be the southern entrance of the Manning River. Concerns regarding the water quality at Farquhar Inlet and the associated state of the local oyster industry were raised by the community during the consultation phase of work that was undertaken by Patterson Britton & Partners (now WorleyParsons) in preparing the ‘Manning River estuary management study’ (GTCC, 2009).
It is understood that frequent and extended closures of the oyster harvest areas in recent years have led to a reduction in the profitability of the shellfish industry. In addition, the condition of water quality at Farquhar Inlet is seen by the community to impact on the recreational value of the lower estuary in the vicinity of Old Bar and has a potential impact on tourism.
The Manning River Estuary Management Study acknowledged these issues and the concerns of the local community. The 'Estuary management plan" that was developed from the study identified the need for further investigation and the development of an Entrance opening management plan for Farquhar Inlet(PDF, 22MB).
Council engaged WorleyParsons to undertake these investigations and to develop the plan. The plan documents the current situation and the issues surrounding the current management of the entrance. It also describes and assesses a range of options that could be implemented to manage the entrance so that the frequency of the water quality and recreational issues that have occurred over recent years is reduced, and provides recommendations for the future management of the entrance.
Manning River maintenance dredging strategy
Dredging of the Manning River estuary commenced in the 1850s to clear a channel from Harrington to Wingham which continued until the 1940s. More recently the need for dredging certain reaches of the river to improve navigation and environmental flows have been identified in the 'Farquhar Inlet Old Bar entrance opening management plan' and the Manning River Estuary Management Plan.
The Manning River maintenance dredging strategy(PDF, 11MB) was adopted by Council in August 2010 and last updated in 2015. The Strategy prioritises dredging within the Manning River estuary so that it is sustainable over the long term. Some 27 dredging sites have been identified ranging from extreme to low priority. The Strategy provides a historical context to dredging in the estuary and provides information on the estuary processes, which result in the need for dredging.
The Strategy also outlines the steps necessary in the planning and implementation of dredging works as well as the legislative requirements, indicative extraction volumes and costs, and potential funding sources. The Strategy essentially provides a strategic framework to assist in the application for funding to achieve maintenance dredging works that have been identified.
We have prepared a guide to help you in undertaking foreshore management works including riverbank restoration.
The guidelines provide information on the legal obligations of landholders as well as other planning considerations that need to be taken into account before undertaking foreshore management works.
They also highlight the opportunities available for landholders to seek technical support and government funding to undertake these types of works.