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Water resources - Management and Development - Queensland

Location map of Lower Oakey Creek Alluvium

Groundwater Management Unit: Lower Oakey Creek Alluvium

Introduction

Management Context:

The Lower Oakey Creek Alluvium GMU is situated within a region of high groundwater usage.

The assessment of the sustainable yield is of high priority to the resource management. In order to achieve the most accurate assessment possible, groundwater level monitoring needs to continue at the same standard for observing aquifer performance.

The GMU is currently allocated to a total of approximately 6000Ml/yr. Although abstraction is less than the amount allocated for the overall area, there is concern that the areas of high concentrations of abstraction bores are full development and any increases in abstraction could effect aquifer performance. Isolated monitoring bores under such conditions have exhibited higher magnitudes in groundwater level declines than bores elswhere in the GMU. Management strategies to limit new or increased allocations are in place to prevent any long- term effects on the quality and quantity of the resource.

There is concern regarding the quality of the groundwater of the GMU. There are plans to reassess the suitability of the existing water quality monitoring network to assess the deterioration in water quality.

Management strategies are currently being developed through the preparation of Management Guidelines for the GMU. Ongoing community awareness and involvement is a priority to the management of the resource. The community is consulted to provide input into the development of management strategies.

Priority issues

Declining Water Levels

 YES

Salt Water Intrusion

 NO

SALINISATION

 

Dryland

 NO

Irrigation

 NO

Groundwater

 NO

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

 YES

Defined Minimum Water Level

 NO

Comment: The GMU is almost fully development with allocations approaching the upper limit. A cap on allocations has been in place since 1996 to control abstraction to sustainable levels.

Comments on Management Responses

2020 Management Response:

The groundwater resource of the Lower Oakey Creek Alluvium GMU is almost fully committed with 90 % of the sustainable yield allocated. It is estimated that the level of abstraction will have reached the sustainable yield of 6500 Ml/yr by the year 2020.

2050 Management Response:

The groundwater resource of the Lower Oakey Creek Alluvium GMU is almost fully committed with 90 % of the sustainable yield allocated. It is estimated that the level of abstraction will have reached the sustainable yield of 6500 Ml/yr by the year 2050.

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

Assessment of monitoring in Lower Oakey Creek Alluvium

Efficacy of the network:

The current monitoring network for the Lower Oakey Creek Alluvium GMU consists of seventeen observation bores.

Monitoring of water levels has occurred since 1962 to the present. Water levels are monitored at least every three months. The monitoring of the groundwater level assists in the interpretation of aquifer performance and as an indication of aquifer storage. The GMU, has concerns regarding water quality and declining groundwater levels. Subsequently, it is desirable that the present level of monitoring continue.

Data management requirements:

Queensland groundwater monitoring data, both water level and water quality, is stored within the Groundwater Database (GWDB) system. The new GWDB 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 Lower Oakey Creek Alluvium GMU aims at maintaining a longterm, sustainable resource and therefore, requires a quantification of the resource, appropriate allocation rates, and accurate monitoring of groundwater extraction, water level and water quality fluctuations.

There needs to be an assessment of the sustainable yield of the resource to determine the long-term effects that the current rate of abstraction may have on the GMU.

Regular monitoring of water quality is essential for protecting the resource from deterioration as well as ongoing groundwater level monitoring.

Options for monitoring:

An assessment of the sustainable yield is required for the Lower Oakey Creek Alluvium GMU and would be the basis for the implementation of long-term sustainable management of the resource.

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: 

A preliminary estimate of the sustainable yield for the Lower Oakey Creek Alluvium GMU is 6500 Ml/yr. This estimate has been based on very limited data.

Sustainable yield:

ML/yr

Threshold year for sustainable year:

2,005 

Abstraction Volume 1996/1997:

2,500 ML 

Current Resource development categorisation:

 

Estimated Use in 2020

Comment:

 

Estimated use in 2020:

6,500 ML 

% change from 1996/1997:

160 

Resource development categorisation:

 

Estimated in 2050

Comment:

 

Estimated use in 2050:

6,500 ML 

% change from 1996/1997:

160 

Resource development categorisation:

 

What assumptions were used in this assessment

Development Potential:

The groundwater resource of the Lower Oakey Creek Alluvium GMU is almost fully committed with 90 % of the sustainable yield allocated. The sustainable yield of the GMU is a very preliminary estimate and as such, groundwater level trends have been considered in conjunction with the level of allocation. Groundwater levels are declining which suggests that the resource is fully developed. There is a limited amount of development potential.

Estimate of Use:

The groundwater resource of the Lower Oakey Creek Alluvium GMU is almost fully committed with 90 % of the sustainable yield allocated. There is a limited amount of development potential without any large-scale water infrastructure.

Data Availability,Gaps and Recommendations

Data Availablility:

The current monitoring bore network within the Lower Oakey Creek Alluvium GMU consists of seventeen bores.

Groundwater levels are regularly monitored and are recorded at least every 3 months. Groundwater samples from private bores and monitoring bores have been collected and analysed. Most bores have only been sampled once with the most recent samples being taken in 1988.

Current Gaps and Recommendations:

Data Gaps: The Lower Oakey Creek Alluvium GMU has a limited amount of data available.

The resource has not been quantified other than preliminary estimates and there have been no groundwater investigations into the GMU.

Groundwater samples from private bores and monitoring bores have been collected and analysed. Recent water quality data is unavailable with most bores having only been sampled once with the most recent samples being taken in 1988. There are isolated bores with high levels of nitrates that have been observed in these samples. There is a limited amount of information regarding this nitrate occurrence.

Recommendations: The main recommendation for the better management of the Lower Oakey Creek Alluvium GMU is to conduct an assessment of the sustainable yield of the resource. This would enable improved management plans through the determination of the size of the resource and the development of appropriate allocations in line with the sustainable yield.

It is recommended that sampling for groundwater quality be conducted. The most recent sampling was in 1988 during routine bore maintenance.

Future Gaps:

The Lower Oakey Creek Alluvium GMU has limited documentation. Information gaps exist with regards to the frequency of monitoring of water quality and the type of water analysis. Water quality data is limited to 1988 records for the GMU. There is no recent data available pertaining to the concerns for pollutants in the recharge contributions from the Toowoomba Sewage Treatment Plant, or contaminants from pesticides used regularly in this region.

There have been no groundwater investigations into the resource of the GMU. Data pertaining to the aquifer properties and size of the resource are unavailable. There is a need for these details to be determined to assess the sustainable yield of the resource so as to develop management plans that comply with protecting the resource from long-term damage.

Further information

Key

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