Introduction

Condition

Pressure

Response

Introduction

The Little Swanport River is an intermittent watercourse with a catchment area of 87,600 ha of which approximately 27% has been developed as pasture for fine wool production, sheep and beef cattle (19%) and for forestry (8%). The rest of the catchment is in natural condition. The estuary supports an extensive aquaculture industry. Annual rainfall throughout the catchment varies from 200 mm to 1,300 mm with a mean of 630 mm (Bureau of Meteorology 2002). Analysis of long-term rainfall data indicates a trend towards a lower-than-mean rainfall since 1970.

The catchment has a resident rural population of around 750. This number can increase to around 1,000 during holiday periods. Many coastal recreational and small business activities cater for considerable numbers of weekenders, holidaymakers and retirees. (Little Swanport Catchment Committee 2001).

The significant values of the native riparian vegetation in the catchment include:

• a diverse range of native species which includes many Tasmanian endemics (Wintle 2002); 85 native species were recorded in the riparian zone at one site along the Little Swanport River-the highest number recorded in an extensive Statewide survey (Daley 2003);
   
• its bank and channel stabilizing properties in an area prone to scour, gully and tunnel erosion (Little Swanport Catchment Committee 2001);
   
• its role in the provision of shade and habitat for at least seven species of native freshwater fish, including two that are nationally listed as vulnerable under Tasmania's Threatened Species Protection Act 1995 and the Commonwealth's Environment Protection and Biodiversity Conservation Act 1999;
   
• its role in maintaining good water quality by buffering stream against nutrient and sediment runoff from areas of intensive agricultural use; and
   
• its role in recreational fishing, walking and research.
   

Condition

While only one-third of the catchment has been extensively developed for commercial purposes, the impacts on the land and water quality from the agricultural and forestry practices on the remaining native riparian vegetation of the catchment has been significant. Results of a recent study of flooding effects on riparian vegetation in the catchment suggest that the hydrological requirements of riparian vegetation are poorly understood (Wintle 2002).

Healthy stands of native riparian vegetation adjoining native terrestrial vegetation are still present along the Little Swanport River and considerable reaches are protected by permanent conservation covenants established as a consequence of the Regional Forest Agreement. In the upper catchment and at the near coastal reaches, the riparian vegetation condition is significantly degraded as a result of:

• extensive clearing of native riparian vegetation from the early 1800s to the present;
   
• invasion of exotic species (especially gorse - Ulex europeus) in the developed reaches and rice grass (Spartina anglica) along the estuary and near-coastal riparian reaches);
   
• changes to environmental flows as a result of multiple in-stream dams and excessive takes of water from the catchment;
   
• the cumulative impacts of the above problems and inappropriate land use practices on catchment hydrology and water-dependent ecosystems; and
   
• inappropriate decisions being made concerning land use activities because of a lack of adequate and current information and data.
   

Pressure

Individual and cumulative pressures from land use and water management practices are having an impact on native riparian vegetation and the ecosystems that depend on the health of the riparian zone. The major pressures (Little Swanport Catchment Committee 2001) are:

• increased nutrient loads and sedimentations resulting in degraded water quality;
   


• increases in water abstraction and multiple in-stream dam construction resulting in a decline in water quantity and therefore flood events and flushing capacity important for maintaining riparian health;
   


• moderate risk of extensive soil salinity problems in the developed areas of the catchment;
   


• large areas prone to scour, gully and tunnel erosion. If surface vegetation is disturbed, this could lead to further increases in loads of in-stream and estuarine sedimentation;
   


• extensive areas of tree decline in the upper catchment and the resulting impact on the structural integrity of riparian vegetation; and
   


• climate change predictions that indicate decreased rainfall in an already dry area.
   

As well as catchment-based land use, water and land management pressures, there are regional pressures for improving farm productivity and increasing water storage (DPIWE 2001). The current ad hoc fresh water development proposals and processes for dam construction and water takes, both of which interfere with ecological processes and delivery of ecosystem fresh water needs, are taking place without knowledge of the needs of fresh water dependent ecosystems in drier regions like the east coast.

Response

A gradual decline in water quality and quantity over the past 30 years prompted the catchment community to become proactive with respect to catchment management planning and riparian protection and rehabilitation. The major actions that were taken to address the pressures and impacts these were having within the catchment are summarised as follows.

Integrated Catchment Management. In July 1998, a Catchment Committee was formed with representatives from the farming, forestry, aquaculture and tourism sectors and from each of the two municipalities comprising the catchment through which the river flows. Later that year, funding for the development of a plan and on-ground works was obtained from the Natural Heritage Trust (Little Swanport Catchment Committee 2001). There is a general belief that, where the landholders adhere to the principles of integrated catchment management and sustainable development, there will be on-going protection and improvements in riparian vegetation cover and riverine ecosystem health.

Catchment management planning. A catchment management plan has been developed over the last three years in parallel with many on-ground actions. A catchment management plan implementation group has been formed to facilitate the necessary actions identified in the catchment management plan.

Elimination and management of exotic species. The elimination of rice grass infestations throughout the Little Swanport Estuary, totalling 10 ha (Hedge 1997), has allowed the return of water birds, fish, and crustaceans to those previously infested areas. This is a great source of pride and enjoyment to those involved and is the motivating force behind the necessary monitoring program in place to locate any future isolated plants (Col Dyke, Little Swanport Catchment Committee, pers. comm., 2002). The community has also been successful in clearing gorse (Ulex europeus), willow (Salix fragilis) and paddock weeds from many riparian areas.

Fencing riparian reaches and providing off-stream watering alternatives for stock. Native riparian vegetation is re-establishing in many of these areas.

Conservation, reservation and management of native riparian vegetation. Approximately 15 km of the riparian vegetation in the mid-reaches of the Little Swanport River have been protected by permanent covenants as a result of being included in four CAR reserves under the Regional Forest Agreement.

Data sources and knowledge base. Members of the catchment community have investigated databases related to the catchment and have assisted with updating information about riparian vegetation species and communities, number of in-stream dams within the catchment and changes in water quality and quantity over time. The information available from the oyster industry at the mouth of the catchment has been especially relevant as a measure of health for the rest of the catchment (Dyke and Dyke, 2002).

Research opportunities. Greater community participation and wider regional, Statewide and national partnerships are being sought to facilitate economic, environmental, research and development needs of the catchment. Areas under consideration include relationships between riparian vegetation and aquatic invertebrates and hydrologic needs of water-dependent ecosystems that include riparian vegetation.

It is the hope that these partnerships will provide a more positive and ecologically sound knowledge base from which to find a sustainable balance between future development and conservation needs of the inland and coastal fresh water dependent ecosystems of this east coast catchment.