Australian Natural Resources Atlas

Natural Resource Topics

Water resources - Management and Development - Queensland

Location map of Mary River

Groundwater Management Unit: Mary River

Introduction

Management Context:

In 1985, significant areas within the GMU were being adversely affected by increasing dryland salinity. At this time, concern was expressed over the potential for enhancement of dryland salinity occurrence, due to rising water levels resulting from excessive infiltration of irrigation waters, unless strict controls on irrigation rates of application and suitable drainage schemes were introduced. Scalded areas occur in the lower topographic areas of the GMU and mostly overlie the sediments of the Maryborough Formation. The area affected by rising salinity has steadily increased due to the combination of extensive landclearing, allowing for sugar cane cultivation, and resultant rising water levels combined with a steady increase in the use of irrigation. The geology of the GMU appears to play a signifcant role in determining those areas that may be adversely affected by increasing salinity, resulting either from land clearing or from increased irrigation activity throughout the region. There is increased potential for areas of saline seepage to occur at the outcropping contact between the Elliott Formation and the underlying Graham's Creek or Maryborough Formations, and mostly towards the base of hillslopes. The potential for seepage to occur at points of outcrop of the highly fractured shales contained in the Maryborough Formation is great because of the confined state of the aquifers in the fractured shales.

Most of the groundwater located in the GMU is of poor quality, with the exception of groundwater contained within the Tertiary Elliott Formation. The extensive distribution of poor quality groundwater throughout the GMU was highlighted in 1985 as contributing towards the potential development of saline affected areas, resulting from rising water tables.

Priority issues

Declining Water Levels

 NO

Salt Water Intrusion

 YES

SALINISATION

 

Dryland

 YES

Irrigation

 NO

Groundwater

 YES

Surface Water

 NO

Urban

 NO

Point Source Pollution

 NO

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

Comments on Management Responses

2020 Management Response:

The estimate of 1000 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 1000 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 Mary River

Efficacy of the network:

The current monitoring network for the Mary River groundwater management unit (GMU) consists of 24 observation bores, with a proposed quarterly monitoring frequency.

In 1985, the need for water level monitoring initiated the development of a reasonably extensive monitoring program. All observation 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. Several of the observation bores presented with artesian flow conditions at the time of drilling.

Water levels have been regularly monitored in all observation bores on an approximately quarterly basis since 1985 to the present. 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 Mary River 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 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 Mary River groundwater management unit does not directly aim at maintaining a longterm, sustainable resource due to the provision of an alternate surface water supply and the poor quality and quantity of the available groundwater. Consideration of the groundwater resource however, is still required due to the detrimental affects of salinity upon landuse within the GMU. Protective management requirements for the Mary River groundwater management unit 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 excessive infiltration of irrigation waters.

Continuation of water level and water quality monitoring in an effort to identify and appropriately manage tidal salt water intrusion within alluvial aquifers, 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.

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 Mary River 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 tidal salt water intrusion within alluvial aquifers, 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.

The installation of a program to cap the free flowing artesian bore and a bore maintenance program is required to enhance the resource management of the GMU.

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 1000 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:

2,005 

Abstraction Volume 1996/1997:

1,000 ML 

Current Resource development categorisation:

 

Estimated Use in 2020

Comment:

 

Estimated use in 2020:

1,000 ML 

% change from 1996/1997:

0 

Resource development categorisation:

 

Estimated in 2050

Comment:

 

Estimated use in 2050:

1,000 ML 

% change from 1996/1997:

0 

Resource development categorisation:

 

What assumptions were used in this assessment

Development Potential:

Groundwater quality and quantity within the Mary River GMU varies greatly with the diversity of lithology and geological age of the aquifers. The groundwater resources of the GMU are mostly limited, with only the alluvial deposits in the lower Mary River- Tinana Creek area capable of groundwater yields adequate for irrigation purposes, with these supplies threatened by salt water intrusion. The groundwater resources of the Mary River GMU are not expected to sustain any significant increase in development due to their variable quality and quantity, and additional threat of saltwater intrusion. The forecast use estimate for the years 2020 and 2050 is unlikely to be exceeded due to the provision of an alternate surface water supply and the poor quality and quantity of available groundwater.

Estimate of Use:

The estimate of 1000 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:

The availability of water level data is moderate, with almost continuous water level monitoring, on an approximately quarterly basis from 1985 to the present, of the 24 observation bores within the GMU. Comprehensive water quality data exists for 24 observation bores within the GMU, with recent analyses from 1990 to the present.

Current Gaps and Recommendations:

Data Gaps: Water level data gaps exist for the year of 1993 for all observation bores in the GMU. Formal use and allocation data is not available. 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 Mary River 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:

Reinstallation of a comprehensive water quality monitoring program would enhance the resource management of the Mary River 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.

Further information

Key

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