Australian Natural Resources Atlas

Natural Resource Topics

Water resources - Management and Development - Queensland

Location map of Isis River

Groundwater Management Unit: Isis River

Introduction

Management Context:

Dryland salinity affects significant areas within the Isis GMU, with concern expressed over the possibility for enhancement of this problem due to rising water levels resulting from excessive infiltration of irrigation waters. Saline scalded areas occur throughout the GMU, with most occuring in the lower topography areas, and overlying the sediments of the Maryborough Formation and Burrum Coal Formation. The area affected by rising salinity has steadily increased with extensive landclearing and the resulting rising water tables, combined with the increased intensity of irrigation and the natural occurrence of poor quality groundwater.

The geology within the Isis GMU is significant in determining those areas affected by increasing salinity. The potential for seepage to occur at points of low topography in the Maryborough Formation, Graham's Creek Formation and the Burrum Coal Measure, is due to the elevated water table in these geological units. However, saline seepage areas within the Tertiary Elliott Formation appear to result from a perched water table intersecting the surface rather than the regional water table. The perched water table occurs due to a thin impermeable layer located close to the natural surface which results in a perched water table intersecting the surface. The regional water table lies well below the existing topography and therefore makes no contribution to the saline seepages in these areas.

Priority issues

Declining Water Levels

 NO

Salt Water Intrusion

 NO

SALINISATION

Dryland

 YES

Irrigation

 NO

Groundwater

 YES

Surface Water

 NO

Urban

 NO

Point Source Pollution

 YES

Diffuse Source Pollution

 NO

Subsidence

 NO

Artificial Recharge (ML/yr)

 no data

Ecosystems Protection

 NO

Surface Water Interaction

 NO

Management Plans

 NO

Defined Minimum Water Level

 NO

Comment: Point source pollution arising from septic tanks, rising water levels due to changes in landuse, and excessive infiltration of irrigation waters resulting in waterlogging are other priority issues for the Isis River GMU.

Comments on Management Responses

2020 Management Response:

The estimate of 3000 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 3000 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 Isis River

Efficacy of the network:

The current monitoring network for the Isis River groundwater management unit consists of 28 observation bores, with a proposed monthly monitoring frequency.

The need for an extensive observation bore network was identified in 1989 due to the effect of irrigation upon dryland salinity. All bores were drilled through any alluvial material and into the underlying sedimentary or volcanic formations according to their location. Except for those observation bores located in alluvium, all were drilled until a significant water supply was encountered in the underlying formation.

Water levels have been continuously monitored since 1985 in the Isis groundwater management unit on an approximately quarterly basis however, comprehensive water quality data is only available until 1991. Reinstallation of a comprehensive water quality monitoring program would enhance the resource management of the Isis GMU and allow for the assessment of water quality fluctuations, the detection of water quality trends and assist 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 licence 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 Isis River groundwater management unit aims at maintaining a longterm, sustainable resource and therefore, requires appropriate allocation rates, and the accurate monitoring of groundwater extraction, water level and water quality fluctuations. There is presently a proposal to increase the Bundaberg declared sub-artesian area into the northern section of the Isis GMU within the next five years. Increasing the declared area will require a detailed resource investigation and allow for a higher level of resource management, with greater inputs into allocation and abstraction of groundwater.

Protective management requirements for the Isis River GMU include:

Development and application of strict controls on irrigation rates and suitable drainage schemes in an effort to reduce the potential for enhancement of dryland salinity occurrence, due to rising water levels resulting from changes in landuse and excessive infiltration of irrigation waters.

Continuation of water level and water quality monitoring in an effort to identify any changes to saline affected areas and extent of waterlogging by allowing the assessment of both water level and water quality fluctuations, and the detection of both water level and water quality trends from collected data.

Options for monitoring:

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

Reinstallation of a comprehensive water quality monitoring program to enhance the resource management of the Isis GMU, by allowing 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.

Continuation of water level and water quality monitoring in an effort to identify and appropriately manage rising water levels, water logging and salinity issues by allowing the assessment of both water level and water quality fluctuations, and the detection of both water level and water quality trends from collected data.

Completion of a detailed resource investigation to provide the basis for the proposed increase to the Bundaberg declared sub-artesian area into the northern section of the Isis GMU within the next five years. Comprehensive aquifer assessment and quantification of the groundwater resource will also allow for a more accurate assessment of sustainable yield and development potential., whilst increasing the declared area will allow for a higher level of resource management with greater inputs into allocation and abstraction of groundwater.

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 3000 Ml/yr for sustainable yield was made in 2000 based upon the extent and nature of the aquifer.

Sustainable yield:

ML/yr

Threshold year for sustainable year:

1,995 

Abstraction Volume 1996/1997:

no data ML 

Current Resource development categorisation:

Estimated Use in 2020

Comment:

Estimated use in 2020:

3,000 ML 

% change from 1996/1997:

no data 

Resource development categorisation:

Estimated in 2050

Comment:

Estimated use in 2050:

3,000 ML 

% change from 1996/1997:

no data 

Resource development categorisation:

 

What assumptions were used in this assessment

Development Potential:

Groundwater quality and quantity within the Isis GMU varies greatly with the diversity of lithology, state of confinement and geological age of the aquifers. The groundwater resources of the Isis GMU are not expected to sustain any significant increase in development due to their variable quality and quantity. However, there is presently a proposal to increase the Bundaberg declared sub-artesian area into the northern section of the Isis GMU within the next five years. Increasing the declared area will require a detailed resource investigation and allow for a higher level of resource management.

Estimate of Use:

The estimate of 3000 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 100 observation bores, both private and State owned, are located within the Isis GMU. The availability of water level data is moderate, with continuous water level monitoring, on an approximately quarterly basis from 1985 to the present in 28 observation bores. Comprehensive water quality data exists for 17 observation bores within the GMU, with recent analyses from 1993 to the present.

Current Gaps and Recommendations:

Data Gaps: Formal use and allocation data is not available for the Isis GMU. Comprehesnisve water quality data is only available until 1991.

Recommendations: Reinstallation of a comprehensive water quality monitoring program would enhance the resource management of the Isis 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. Comprehensive aquifer assessment and quantification of the groundwater resource will allow for a more accurate assessment of sustainable yield and development potential.

Future Gaps:

Comprehensive aquifer assessment and quantification of the groundwater resource in preparation for possible extension of the Bundaberg declared sub-artesian area will allow for a more accurate assessment of sustainable yield and development potential to be made for the Isis GMU. Reinstallation of a comprehensive water quality monitoring program would enhance the resource management of the Isis GMU and allow for the assessment of water quality fluctuations, the detection of water quality trends and assist in the development of management strategies to prevent further deterioration in groundwater quality.

Further information

Key

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