Issue: Land quality in Tumut Shire, Australia

Issue: Land quality in Tumut Shire

Assessment

Land quality in Tumut Shire is most influenced by historical landuse practices, such as clearing for agriculture. More recently, subdivision of rural lands for rural-residential purposes has become an increasing potential pressure on land quality in the Shire.

Agriculture and forestry have traditionally been the main pressures on land quality. Some 50% of the Shire has been cleared, with the result that just over half of the original ecodiversity has been lost. Areas that have been cleared have experienced levels of soil erosion typical of many other Shires in the Region.

The extent of clearing and subsequent soil degradation is not reflected in the water quality of rivers flowing through and out of the Shire, with the few water quality parameters measured falling within ANZECC guidelines. However, there are only four monitoring stations in the entire Shire, and data for these were not available for the entire reporting period. This represents a decline in monitoring effort, because more data were available for the last Regional State of the Environment Report in 1997.

In the 1997 State of the Environment report we stated that State forests are covered by Management Plans which control activities and implement environmental safeguards, particularly soil erosion and associated siltation of watercourses. This is still the case, although the data to demonstrate the efficacy of these measures are not available.

The pressure on land quality that arises from the community's use and disposal of resources in Tumut Shire appears to be increasing with increases in the amount of waste taken to landfill during the reporting period, with much of this comprising domestic waste. The amount of materials appears to have changed little, particularly in the last two years (1998–2000). However, the lack of data about site contamination makes it difficult to draw any conclusions about the impact of this on land quality.

In the 1997 State of the Environment Report, a concern was raised about the potential for contamination from hazardous waste production and storage in the Shire. The extent to which this pressure was realised was then unknown. Council has indicated that limited resources have hindered progress in further identification and investigation of potentially contaminated sites.

Implications

Land quality is one of Australia's greatest natural resources concerns, and progressive land degradation is often suspected. The situation in the Murray-Darling Basin has alerted all of Australia to the relationship between land and water quality. Without regular and systematic measurements, based on the land quality indicators, there can be no reliable comparison of land quality for the Australian Capital Region. Management and planning at the Local Government level is also hampered by the unavailability of current and reliable data.

Background

Healthy land is needed to sustainably support a range of important landuses such as agriculture, urban development, waste disposal or transport infrastructure. For this reason, land quality, or the extent to which the soil resource is free from depletion or degradation, is of concern to many communities.

Ideally, land quality would be assessed in this report on the basis of fundamental soil properties which reflect the condition of the soil, and the actual and likely extent of degradation such as soil erosion and dryland salinity. Factors such as the occurrence of known contaminated sites, or the detrimental effects of landfill are also considered.

Declines in land quality can often be remediated once the problem and its causes have been identified. This may mean applying lime or fertilisers, restricting areas to stock access, revegetating some agricultural catchments, imposing erosion control measures in urban development areas, changing to a more appropriate landuse, or simply not developing some areas of land identified as having a high risk of developing dryland salinity.

Although they are difficult to map, soil properties such as the nutrient status and structural condition are important. Declining amounts of soil nutrients after continued harvesting can cause serious declines in the production of basic resources such as food if soil nutrients are not replaced. Similarly, the ability of plants to grow is much reduced in soils compacted by traffic, farm and construction machinery. There are also impacts on soil biota, and the way in which soils transfer water—leading to increased amounts of runoff following rainfall. Land reshaping for urban development is an important cause of a decline in land quality in urban areas.

Erosion and salinity can be of equal concern to urban areas due to the threat to road and building infrastructure. Further problems arise from rivers and lakes silting up as a result of sediment washed off construction sites and streambanks, and the generation of dust from soils which have had their surface structure destroyed.

Indicators used to assess this issue