Australian Natural Resources Atlas

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Water resources - Management and Development - Queensland

Location map of Three Moon Creek

Groundwater Management Unit: Three Moon Creek

Introduction

Management Context:

A decline in groundwater levels in the early 1990's accompanied by a reduction in bore yield rates, particularly in the latter half of 1995 presents as a priority issue for the Three Moon Creek groundwater management unit (GMU). A decline in water levels in the southern section of the GMU also results in a deterioration in water quality. Groundwater quality deteriorated through the 1970's and 1980's in the area south of Monto. The increased occurrence of saline groundwater downstream of Mulgildie limits groundwater development in this area, with the alluvial sourced town water supply of Mulgildie considered in 1988 to be no longer suitable for domestic purposes. The township of Mulgildie now obtains its water supply from the underlying Precipice Sandstone via a 635 m deep bore however, this new water source requires more expensive processing to meet appropriate health standards. Water supply issues, both quantity and quality, are of considerable concern to the community within the GMU as reliable and continuous water supplies are required for dairying, irrigation and domestic uses.

The nature of the groundwater deterioration and possible rectification strategies were investigated in a comprehensive study of the alluvial groundwater from Monto to Mulgildie in 1990. Although several possible causes of the increasing salt loads were proposed, insufficent data was available to fully understand the processes involved, however the following two processes were summarised and presented in 1993:

1. Irrigation pumping has lowered the groundwater level in the alluvium which has reduced the hydraulic head in relation to that in the adjacent Mulgildie Coal Measures. This has allowed the poorer quality water of the Mulgildie Coal Measure to enter the alluvium groundwater store and reduce the overall quality of the alluvial groundwater.

2. Historic salts stored in the alluvium below the plant root zone and above the groundwater table have been mobilised due to deep drainage of surface water from over irrigation. As a result, salt stored in this zone has been leached down through the alluvial profile and into the groundwater.

Management strategies for the deterioration in groundwater quality include proper irrigation management, mixing of poorer quality and good quality water, night time irrigation to reduce evaporation effects and water balance methods.

Salinity also occurs within the Three Moon Creek GMU as saline seeps in the dryland pasture areas on the eastern catchment margins. These seeps tend to be associated with the Mulgildie Coal Measures and are of limited surface extent, commonly occurring in gully lines. Other saline seeps are prevalent in the Precipice Sandstone northwest of Monto and are most likely geologically controlled and a result of movement of poor quality groundwater along geological faults to the surface. Again, the surface expression of the seeps is limited, with the source of salinity uncertain but possibly derived from coal sequences within the sedimentary rocks or from adjacent volcanic rocks. Suggested management strategies for the affected sites include revegetation with salt tolerant grasses and trees to use available water and reduce evapotranspiration, and isolation of affected areas to facilitate their flushing during storm events.

The dependance of the groundwater resources of Three Moon Creek GMU upon the operation of Cania Dam was highlighted as a priority issue in 1984. The potential failure of Cania Dam for any period of time, could be expected to result in severe aquifer failure in some areas of the GMU due to the high level of groundwater and surface

 

Management Context:

water demand. Recommendations at this time suggested that preliminary investigations be performed into the feasibility of extracting groundwater from the outcrop areas of the Precipice Sandstone for discharge into Three Moon Creek. In 1986, a groundwater model of the area was proposed to be completed to allow for the effective management of water resources in the Three Moon Creek GMU. The proposed model would incorporate the recharge scheme, of groundwater augmentation from Cania Dam, and should be capable of determining the operation rules for the entire scheme.

Management of the groundwater resource of the Three Moon Creek GMU aims at maintaining a longterm, sustainable resource, and therefore, requires appropriate allocation rates, tools and the accurate monitoring of groundwater extraction, aquifer level and water quality fluctuations. Management tools for Monal and Splinter Creeks were outlined in the 1996 Draft Monal/Splinter Groundwater Management Plan. Regional objectives of the Water Resource Commission (now the Department of Natural Resources), outlined in the 1989 Burnett Region Management Plan, extend past the Three Moon Creek GMU to the greater Burnett Region.

Priority issues

Declining Water Levels

 YES

Salt Water Intrusion

 NO

SALINISATION

 

Dryland

 NO

Irrigation

 YES

Groundwater

 YES

Surface Water

 NO

Urban

 NO

Point Source Pollution

 YES

Diffuse Source Pollution

 YES

Subsidence

 NO

Artificial Recharge (ML/yr)

 no data

Ecosystems Protection

 NO

Surface Water Interaction

 YES

Management Plans

 NO

Defined Minimum Water Level

 NO

Comment: Demand for groundwater resources is in excess of the available groundwater resource, resulting in increased competition for water allocation.

Comments on Management Responses

2020 Management Response:

The estimate of 22524 Ml/yr for the forecast use for the year 2020 is based upon the GMU's assessed sustainable yield, development potential and the desired level of resource management.

2050 Management Response:

The estimate of 22524 Ml/yr for the forecast use for the year 2050 is based upon the GMU's assessed sustainable yield, development potential and the desired level of resource management

See QLD Water Resources Assessment 2000 Technical Report for a review of management responses.

Assessment of monitoring in Three Moon Creek

Efficacy of the network:

The current monitoring network for the Three Moon Creek groundwater management unit (GMU) consists of 87 observation bores, with a proposed bi-monthly to quarterly monitoring frequency.

Water levels have been continuously monitored in all observation bores on an approximately quarterly basis, some since 1961 to the present. The overall rise in groundwater conductivity indicates that continued monitoring is required of the groundwater, including the sources of recharge and drainage paths. Comprehensive water quality monitoring data is only available until 1991. Reinstallation of a comprehensive water quality monitoring program would enhance the resource management of the Three Moon Creek GMU and allow for the assessment of water quality fluctuations, the detection of water quality trends and aid in the development of management strategies to prevent further deterioration in groundwater quality.

Data management requirements:

Queensland groundwater monitoring data, both water level and water quality, is stored within the Groundwater Database (GWDB) system. The new system is based on web technology and is available through the department's intranet. Allocation and use data is obtained through the Water Entitlements Registration Database (WERD) which is an electronic database for water license details. Both databases are managed locally at district level, with respect to the collection and entering of water monitoring, allocation and use data; and are accessed statewide.

Protective management:

Management of the groundwater resource of the Three Moon Creek groundwater management unit aims at maintaining a longterm, sustainable resource and therefore, requires the accurate monitoring of water level and water quality fluctuations.

Protective management requirements for the Three Moon Creek GMU include:

reinstallation of a comprehensive water quality monitoring program to enhance the resource management of the Three Moon Creek GMU, allowing for the assessment of water quality fluctuations, the detection of water quality trends and assistance in the development of management strategies to prevent further deterioration in groundwater quality

improving and developing the understanding of sustainable land use capabilities within the GMU by considering local soil types, climate, topography, farming methods, water availability, and soil and water degredation issues

enhancement of aquifer assessment and quantification of the groundwater resource by construction of a groundwater model to use as a predictive tool for resource management within the GMU with respect to groundwater response, both water level and water quality, to changes in future groundwater use. The proposed model would incorporate the recharge scheme, of groundwater augmentation from Cania Dam, and should be capable of determining the operation rules for the entire scheme.

Options for monitoring:

Options for Commonwealth and State agencies to address data and information gaps include:

the reinstallation of a comprehensive water quality monitoring program to enhance the resource management of the Three Moon Creek GMU, allowing for the assessment of water quality fluctuations, the detection of water quality trends and assistance in the development of management strategies to prevent further deterioration in groundwater quality

addressing deficiencies in existing knowledge and understanding of resource and catchment management processes within the GMU with futher investigation into the incidence of saline outbreaks in the adjacent uplands under current land management practices, in addition to identification of the source(s) of salts causing rapid deterioration in the alluvial water supply.

enhancement of aquifer assessment and quantification of the groundwater resource by construction of a groundwater model to use as a predictive tool for resource management within the GMU in assessing groundwater response, both water level and water quality, to changes in future groundwater use. The proposed model would incorporate the recharge scheme, of groundwater augmentation from Cania Dam, and should be capable of determining the operation rules for the entire scheme.

See QLD Water Resources Assessment 2000 Technical Report for a review of monitoring.

What is the estimated demand for groundwater?

Sustainable Yield

Comment about sustainable yield figure: 

An assessment of 22524 Ml/yr for sustainable yield was made in 1996 for the Three Moon Creek groundwater management unit (GMU).

An assessment of 15100 Ml/yr for estimated annual yield of Three Moon Creek, with a 2-10% risk of failure, was made in 1984 based upon a lumped parameter model. An assessment of 2510 Ml/yr and 4914 Ml/yr for the total annual groundwater available for Monal and Splinter Creeks respectively was made in 1996 based upon water balance methods.

Cania Dam, Youlambie Weir and Monto Weir all contribute to groundwater augmentation along Three Moon Creek and the lower reaches of Monal Creek. The rate of recharge from the Monto Weir at full capacity is approximately 2.5 Ml/day, with the combined total recharge from Youlambie and Monto Weir being approximately 300 Ml/yr.

Sustainable yield:

ML/yr

Threshold year for sustainable year:

1,995 

Abstraction Volume 1996/1997:

8,658 ML 

Current Resource development categorisation:

 

Estimated Use in 2020

Comment:

 

Estimated use in 2020:

22,500 ML 

% change from 1996/1997:

160 

Resource development categorisation:

 

Estimated in 2050

Comment:

 

Estimated use in 2050:

22,500 ML 

% change from 1996/1997:

160 

Resource development categorisation:

 

What assumptions were used in this assessment

Development Potential:

The increased occurrence of saline groundwater downstream of Mulgildie limits groundwater development in this southern section of the Three Moon Creek (GMU). Surface water is the main source of water supply downstream of Mulgildie due to the poor quality of available groundwater. A 1999 report further recommends that the groundwater level should be controlled within the expanded irrigation area to prevent saline baseflow from entering the streams. A decline in groundwater levels in the past few years, accompanied by a reduction in bore yield rates is a present concern in the GMU, and represents another factor limiting potential development in the Three Moon Creek GMU.

Estimate of Use:

The estimate of 22524 Ml/yr for the forecast use for the years 2020 and 2050 is based upon the GMU's assessed sustainable yield, development potential and the desired level of resource management.

Data Availability,Gaps and Recommendations

Data Availablility:

In excess of 900 observation bores, both private and State owned, are located within the Three Moon Creek GMU. The availability of water level data is high, with continuous water level monitoring in 87 observation bores, some from 1961 to the present,on an approximately quarterly basis. Comprehensive water quality data exists for 169 observation bores within the GMU, with recent analyses to 1991. Formal use and allocation data is available for the GMU from the Water Entitlements Registration Database (WERD) as the GMU is within the declared Monto sub-artesian area.

Current Gaps and Recommendations:

Data Gaps: Comprehensive water quality data is only available until 1991.

Recommendations: Reinstallation of a comprehensive water quality monitoring program would enhance the resource management of the Three Moon Creek GMU, allowing for the assessment of water quality fluctuations, the detection of water quality trends and assistance in the development of management strategies to prevent further deterioration in groundwater quality.

Future Gaps:

In 1993, deficiencies in existing knowledge and understanding of resource and catchment management processes within the Three Moon Creek GMU were identified, with acknowledgement that improvement in these areas would contribute towards:

1. the identification of the source(s) of salts causing the rapid deterioration in the alluvial water supply.

2. the determination of future trends in groundwater salinity and the incidence of saline outbreaks in the adjacent uplands under current land management practices.

3. the identification of the major catchment issues that the community understand as affecting both present and future viability and lifestyle.

4. the understanding of sustainable land use capabilities within the GMU by considering local soil types, climate, topography, farming methods, water availability, and soil and water degredation.

Further information

Key

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