Issue: Water quality and ecology in Tumut Shire

| Assessment | Implications | Recommendations/Objectives to be achieved |
| Background | Indicators used to assess this issue |

Assessment

In the 1997 State of the Environment Report, it was stated that all rivers and streams in the Shire were polluted, apart from those streams draining upland catchments within the Kosciuszko National Park. AUSRIVAS monitoring now indicates that half of the streams monitored are in good condition but that the remainder are in fair to poor condition, suggesting that river health should remain a key issue in the Shire. Streams are exposed to a number of pressures from recreational and timber industry users. Erosion of stream banks occurs in response to controlled releases from Blowering Dam, and hillslope erosion occurs when soils are exposed by forest clearing practices.

The condition of riparian vegetation and streams is highly variable across the Shire in response to the condition of catchments. Where catchments are largely undisturbed, stream condition and riparian vegetation condition is generally good. In disturbed catchments, particularly where roads dissect forests, stream condition and riparian vegetation condition decreases.

By contrast, despite the limitations of a small number of monitoring sites, the evidence suggests that water quality in streams is generally good, with low salinity levels and low to medium turbidity for the current period. A measurable increase in drinking water quality has occurred since the 1995–97 recording period and the quality of potable water is considered to be very good throughout the Shire.

Implications

The Tumut River Management Strategy 2000 is addressing erosion and channel capacity problems. The current five year program is addressing identification and stabilisation of erosion sites and willow lopping activities on the Tumut River.

A number of Bidgee Banks projects have been approved for the Shire in 2000, which will address streambank rehabilitation and riparian zone amelioration.

Timber production has the potential to impact on water quality. This can be minimised through adherence to Forest Codes of Practice (State Forests of NSW 1998) by forest managers.

Recommendations/Objectives to be achieved

The water quality of Tumut Shire can be better characterised if the monitoring network is extended and includes a broader range of parameters so that fluctuations in nutrient, sediment and temperature levels can be detected and point or diffuse sources identified. This process will assist decision making for better management.

Forest managers, in controlling impacts associated with timber production activities, could further improve water quality.

Background

Climate, streamflow and the supply of sediments, nutrients and pollutants all define water quality. An increase in rainfall generally promotes better water quality by increasing streamflow and turbulence.

Human use of water, streams and riparian environments can potentially have enormous impacts on the aquatic biota, as well as on the potential use of water as a resource. The Tumut River has been modified by the construction of a number of large impoundments, which will alter the natural flow regime of the river with consequent impacts on aquatic ecosystems. Inputs of sediment also occur through forest management practices in catchments. Although these impacts should be minimal if Forest Codes of Practice are followed diligently, the absence of a comprehensive monitoring network is a constraint on understanding the dynamics of the systems in the Shire. Modification of the stream channel by grazing, recreational use or modification of the riparian zone can also modify aquatic habitat to the point that it can no longer support original populations of native aquatic species.

The intended use of water determines the required water quality. In this report, the main uses (these can be called environmental values) are:

• conservation of aquatic ecology
• recreation
• drinking water
• aquaculture
• agriculture, including livestock and irrigation.

Any interpretation of water quality should take into account the intended use, or uses, of that water, and it is hoped a more comprehensive analysis of water quality related to intended use or uses can be incorporated into the next comprehensive State of the Environment Report. Such information was not available for this Report.

Water quality is affected by a range of activities in the catchment. Inappropriate landuse can add sediment or other contaminants to groundwater and surface water; use of the water itself can concentrate pollutants or other substances in the water; runoff from urban and rural catchments can bring large quantities of unwanted substances into waterways if not properly treated.

Indicators used to assess this issue