Yass Valley

Issue: Catchments

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How has catchment quality changed?

Yass Valley Council area is located in the area covered by the Murrumbidgee and Lachlan Catchment Management Authorities. The Council area covers approximately 3,985 square kilometres, has a population of approximately 13,000 and is strongly rural in character.

Insufficient data was available for Yass Valley Council area to assess changes to, or impacts on, many aspects of catchment quality over the current reporting period. As a result, changes in erosion and groundwater quality are not reported.

Drought was potentially the most significant event affecting catchment quality in Yass Valley over the current reporting period. The drought which dates back to around 1997, is as serious if not worse, than other major prolonged droughts such as those over 1895 to 1903 and 1938 to 1945. Previous extreme drought years include 1902, 1914, 1938, 1940, 1944, 1967, 1982 and 2002. The 2006–07 irrigation season was a record dry season for much of the area.

As water availability has changed, water allocations within the catchment have been adjusted. Water allocations are made in a way that reflects the priority given to domestic and basic rights supplies, then to core environmental needs, then to irrigation and industry. Operational plans for 2007–08 reflect that the catchment experienced one of the lowest inflow periods in history. In many cases, high security licences were permitted to carryover unused water for the first time.

Drought or excessive water extraction causes water bodies to dry out, water quality conditions deteriorate and the fish within them may die or be eaten by birds. This scenario is unlikely for the main river channels, but is likely for many of the smaller creeks and tributaries. Indeed, many of the smaller creeks have already dried back to a series of disconnected pools.

During the drought, salinity levels are generally relatively low. This is due to little or no inflows from higher salinity tributaries and no return flows. Groundwater leakages from saline floodplains are generally also lower. However, if river flows continue to reduce, salinity levels can increase.

With little water available for irrigation there is the potential for substantial economic impacts. Irrigators who grow annual crops generally adjust their planting area depending on water availability. However, irrigators who grow perennial crops are impacted in the long term if they are unable to ensure crop survival.

Over the current reporting period, water allocations that were assigned in July 2006 had to be suspended in October and November 2006, due to the drought and inflows being below previous recorded low inflows. Domestic water restrictions have been imposed. These are used to raise awareness and understanding of the current drought and encourage people to conserve and use water more efficiently, resulting in lower water consumption.

Where are the ‘hot-spots’?

Effluent from Yass is treated at the Yass sewage treatment plant. The plant is licenced to discharge to Banjo Creek, which is a tributary of Yass River, and to Council owned land for irrigation. Yass Valley Council also holds another licence for Yass Water Treatment Plant to discharge backwash water into the Yass River.

The high phosphorus load in the discharge water may contribute algae growth in Yass River. Currently Yass sewage treatment plant has no facility to remove the phosphorus load.

In 2004-2005, the Yass Sewage Treatment Plant exceeded its daily discharge volume limit on 79 occasions, as well as exceeding the river discharge volume / dilution ratio 125 times. In 2005-2006 the daily volume limit was exceeded on 74 occasions, while the number of effluent discharges to the river, when river flow is below 50 megalitres per day, was exceeded on 236 occasions. In 2006-2007, the daily volume limit was again exceeded in 2006-2007 on 16 occasions while the effluent discharge limit was exceeded on 304 occasions. No reports were available for 2007-2008 at the time of reporting.

Landuse in the Yass Valley Council remained relatively stable since the previous reporting period. However, it is expected that the rural residential development within the Council area continued to increase. As such, it is expected that the related erosion and sedimentation to this development would have also increased.

High concentrations of extreme gully erosion occurred in the Murrumbidgee River catchment, specifically in the Yass River and Upper Jugiong Creek subcatchments and along the upper reaches of the Murrumbidgee River. Large areas of severe sheet erosion also occurred in the Lachlan catchment at Boorowa River and the Murrumbidgee catchment at Jugiong Creek, Yass River and Upper Carrolls Creek.

Dryland salinity outbreaks were reported in the upper reaches of the Yass River and in the Murrumbateman Creek subcatchments.

Lachlan Catchment Management Authority identified some of the key challenges facing catchments in Yass Valley as:

the loss of native vegetation across the catchment and resulting land degradation. This is leading to stream and wetland sedimentation, increasing water turbidity, rising watertables and increased salinity levels in waters.
rapidly increasing dryland salinity and some irrigation salinity; associated with rising watertables.
the need for irrigation to remain viable. Irrigation was held to be necessary for agriculture in the river valley and a significant contributor to the catchment's prosperity.
reduce remaining significant point-source pollution, and urban and rural runoff where this is causing water quality problems-particularly turbidity and increased levels of nutrients (DECC:1, 2008).

Murrumbidgee Catchment Management Authority identified some of the key challenges facing catchments in Yass Valley:

use of local knowledge and enthusiasm for social, environmental and economic sustainability, including continuing land care and improving water management.
continue scientific research, monitoring and reporting on river issues.
reverse the loss of native trees and other perennial vegetation across parts of the catchment that is leading to stream and wetland sedimentation, increased water turbidity, rising water tables, increased salinity levels in waters, and urban salinity.
reduce the causes of unnatural rates of river erosion and manage riparian zones to protect remaining native vegetation.
reduce remaining significant point-source pollution (e.g. sewage treatment plants, unsewered villages).
further reduce pollution of stormwater runoff from both urban and rural lands, and contamination of surface or groundwater with pesticides or other chemicals.
enable continuing improvements in efficiency of agricultural and urban water uses.
increase efforts to control exotic plant and animal pests in rivers, particularly carp (DECC:2, 2008).

What has been done to address catchment quality?

A new Sewage Treatment Plant is currently under construction in Yass. The new plant is expected remove a significant proportion of the phosphorus load entering the Yass River. The plant is due to be commissioned at the end of 2009.

Yass Valley Council is currently preparing a Local Environmental Plan and Development Control Plan. The Development Control Plan will provide for opportunities to implement effective erosion and sediment controls in the Council area.

The Council is currently undertaking an urban salinity project for Yass in co-operation with the Murrumbidgee Catchment Management Authority. Tasks within this project include:

preparation and implementation of an urban salinity management plan;
implementation of on ground works targeting saline recharge and discharge areas; and
preparation and implementation of an urban salinity awareness strategy.

Yass Valley promotes the NSW Government’s Rainwater Tank program to be used by residents to reduce potable water demand. The Council also implemented water restrictions over the reporting period.

In addition, in 2004, an embargo was placed on new groundwater extraction licenses due to concerns that the use of groundwater in the Yass River catchment was unsustainable.

What does this mean for Council?

The catchment data supplied from Council and the Department of Water and Energy is lacking for many indicators within Yass Valley. This means that only partial assessment of the catchment quality is ever possible.

There is limited Council monitoring of erosion, sedimentation, salinity, and ground and surface water quality. Therefore impacts from urban and rural development, and significant natural pressures such as drought, cannot be fully determined. The monitoring of the implemented Council strategies and associated actions is also necessary to determine their effectiveness in achieving the desired catchment management outcomes.

Yass Valley should undertake the following actions to ensure environmental improvement in the catchment:

continue to work closely with Murrumbidgee and Lachlan Catchment Management Authorities, to implement joint projects and ensure consistency in approach to land and water management and complementary actions.
continue to build on the effective relationship with NSW State Government agencies to ensure the collection of up to date information regarding condition of the catchments environmental drivers such as salinity, and associated management issues relevant to them.
monitor and adapt to the impacts of climate change to ensure no significant detrimental catchment effect is sustained from the changing conditions and any future actions.
continue to ensure impacts on ground and surface water quality are considered in landuse zoning, development applications, sewage and water supply treatment.
implement appropriate environmental monitoring programs to measure the effectiveness of Council 's policies, strategies, and management activities.
support and encourage sustainable land use and water management in the urban and rural communities. Approach business and industries regarding sustainable practices and monitoring.

References

DECC – see Department of Environment and Climate Change

Department of Environment and Climate Change:1 (2008) NSW Water Quality and River Flow Objectives: Lachlan River Community Comment on Objectives, Department of Environment and Climate Change viewed on 22 October 2008 at, http://www.environment.nsw.gov.au/ieo/Lachlan/report-01.htm.

Department of Environment and Climate Change:2 (2008) NSW Water Quality and River Flow Objectives: Murrumbidgee River Community Comment on Objectives, Department of Environment and Climate Change viewed on 22 October 2008,at http://www.environment.nsw.gov.au/ieo/Murrumbidgee/report-01.htm

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Regional State of the Environment Report 2008