Estuary Management Planning Narrawallee inlet - 2005

 

Home | Water | Coast and Estuaries | Narrawallee Inlet | 2005

Indicator description

What does the Data tell us for 2005

Environmental Overview

Environmental attributes

Environmental issues

Environmental pressures

Natural Resources Management Plan

 

Environmental Overview

Narrawallee Inlet has four main tributaries – Croobyar, Yackungarrah and Currowar Creeks and Garrads Lagoon. The three creeks rise in the escarpment forests within 30km of the coast and wind through agricultural lands joining the estuary in a floodplain and wetland complex. 

Most of the land surrounding the Narrawallee village is bushland, reserved for public recreation, environmental protection or scenic protection.  The 8 sq km catchment of the inlet includes the Narrawallee suburb, part of the town of Milton, large areas of agricultural soils, native forest recently included in the Morton National Park, native forest in private ownership and significant areas of rural residential development.  Approximate resident population for the catchment in 2001 was 500.

The inlet is a mature estuarine complex open to the sea. It has an apparently very stable entrance however a Coastal Hazard Study will soon confirm the dynamics of the beach and Tombola headland.  A large sand shoal is located on the southern shore, and the channel runs permanently along the northern side. A shallow channel extends along the southern side of this shoal.  Storms can send large waves into the inlet, and deposit large volumes of marine sand.  Floods and tides rework and redistribute this sand within the inlet, shoal and beach systems.  The bed of the inlet is Crown Land.

The inlet is a place where marine and terrestrial processes interact to produce a particularly sensitive and complex coastal environment.  The wetland complex and the low-lying farmland represent an infilled drowned valley system that developed to this stage prior to human involvement.  Since European settlement, a variety of works including weirs, walls, infilling and channels have reduced the extent of the estuary to that which exists today.

The estuary in Croobyar Creek ends in a weir that restricts saltwater intrusion into the low lying farmland, as well as providing a source of fresh water for dairying and grazing purposes.

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Environmental attributes include:

  • The estuarine wetlands in both the Narrawallee Creek Nature Reserve and on private lands are in a near natural state. 196 ha are protected under SEPP 14.  Most of the wetlands and adjoining buffer areas are zoned for environment protection.  The estuary has well vegetated foreshore for most of its length, of grey and river mangroves, swamp oaks and bangalay communities. 

  • Narrawallee Creek Nature Reserve has been included on the register of the National Estate due to the diversity and quality of its habitats including mangroves, high dune forest, salt and freshwater lagoons.

  • The Narrawallee Inlet represents a clean and largely unchanged estuarine eco-system involving sea grass beds and an apparent abundance of aquatic species.  It shows only minor modification of habitat with few water quality problems.  The banks are largely stable with only a few instances of undercutting or headcutting.  Water quality testing at the entrance consistently shows excellent water quality as a result of the tidal exchange.

  • The creek system of Narrawallee Inlet and their catchments support a large variety range of ecological communities, some of which are relatively undisturbed.  These are important from a conservation perspective as well as an attractive attribute of the area for many residents and visitors.

  • Despite extensive clearing, a few moist and dry subtropical rainforest pockets remain at and around the Yatteyattah Nature Reserve, as well as on the steeper slops around Milton and in some escarpment gullies. Some assessment of these remnants has been done and they appear to be stable.

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Environmental issues include:

  • Shoalhaven City Council monitoring has revealed poor water quality in the lower reaches of Croobyar, Yackungarrah and Currowar Creeks during the past 10 years at the sampling locations. This has largely been due to high inputs of bacteria, sediment and nutrients, particularly after rainfall events.  Testing revealed high numbers of faecal coliforms in the upper catchment, and low oxygen levels, which are indicative of high organic loading from surface runoff.  Yackungarrah Creek was reported as having the lowest water quality result for any Shoalhaven waterway in the 1997/98 State of the Environment Report, indicating the impact of agricultural and rural residential uses.  All of these water quality indicators can have serious impacts on the aquatic life in the freshwater creeks, and possibly in the upper reaches of the estuary.  These may include direct kills as well as the reduction or significant changes in the habitat of native species.

  • Much of the riparian vegetation from the freshwater ecosystem has been removed on the agricultural lands.  The creek banks are largely unfenced and are grazed by cattle. Weirs restrict the movement of species up Croobyar Creek.  No detailed assessment has been done of the freshwater ecology.

  • An infestation of the invasive marine seaweed Caulerpa taxifolia has been identified in the inlet immediately upstream of the shoals.  This presents a serious threat to the biological diversity (through smothering of aquatic vegetation), amenity and economic viability of local tourist industries that depend on healthy coastal waterways in the Shoalhaven.  This area has been closed to fishing to reduce its distribution to other areas.  More information can be found on the NSW Fisheries web site -  http://www.fisheries.nsw.gov.au .

  • Forest red gum communities, which originally covered the bulk of the Milton farming lands, are now surviving intact in only a small number of locations. 

  • Several areas of localised erosion and undercutting of the bank exist along the lower reaches of the estuary.  Undercutting of the reserve above and below the boat ramp has occurred where there is minimal foreshore vegetation. An active headcut exists on agricultural lands below Garrads Lane Clearing.

  • Some areas of wetlands have been grazed or damaged by vandalism.  There has been some damage to foreshore trees in an attempt to obtain views by some residents.

  • Privet and lantana are the most significant weeds on the fringes of native bushland and threaten native plant communities. Substantial weed control works have been undertaken during 2005 in combination with primary control by contractors under a Envirofund grant and Bushcare volunteer effort.

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Environmental pressures include:

  • Upstream land management practices in the catchment that may influence water quality include (not in order of importance): clearing, residential development; dairy and pig sheds; grazing and degrading of riparian areas; increases in the area of hard surfaces; poor road and driveway maintenance and construction;

  • Narrawallee has 650 hectares of soils with a high probability of acid sulfate layers.  These are the farming lands and wetlands at the top of the estuary. There is some potential for acid sulfate pollution of the inlet from three areas of farmland that were previously wetlands, as well as from drain maintenance;

  • Grazing of cattle occurs along most of the riparian zones and in some foreshore and wetland areas.  This is not necessarily on a permanent basis.  Increased creek bank fencing has been encouraged in an attempt to ameliorate this pressure.  Creeks through the agricultural lands have either minimal native vegetation, or only a thin band;

  • Any future expansion of Narrawallee suburb has the potential to reduce areas of high habitat value;

  • There is some community pressure to dredge the shoals inside the entrance of the inlet in an attempt to improve boating access to flush the inlet.  Narrawallee Inlet, however, is a small estuary, would still have good flushing even if the entrance were significantly narrower.  Dredging would be likely to affect the stability of the narrow foreshore reserve; and

  • Introduced animals, including foxes, domestic and feral cats and dogs, black rats and rabbits, threaten native animal and plant populations.

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Natural Resources Management Plan

Shoalhaven City Council, New South Wales and Commonwealth Government agencies, and the community have prepared and adopted a Natural Resources Management Strategy for Currarong Creek on the 25/06/2002.  It acknowledges past environmental management, attempts to integrate current programs and proposes some new approaches.  We are doing this to safeguard the ecology of the waterways and their catchments, to balance potentially competing uses and to provide a framework for future planning..

Key implementation actions in progress or completed in partnership with SCC and DIPNR and funded under the

Estuary Program include:

  • 2003 Narrawallee Inlet Foreshore Erosion Study and Concept Design $15000;

  • 2003 Inlet Reserve Rehabilitation Plan;

  • 2003-2004 Erosion Remediation Detailed design and REF;

  • 2003-2004 implementation of Bushfire Asset Protection Zones for the village;

  • 2004-2005 Erosion remediation construction $50,000 Stage 1 construction to commence;

  • 2004-2005 Catchment Stormwater Review  $10,000; and

  • 2005 Southern Reserve Bushland Management Strategy $5000

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Surface Water Quality Narrawallee Inlet

Home | Water | Coast and Estuaries | Narrawallee Inlet | 2005