Australian Natural Resources Atlas

Natural Resource Topics

Water resources - Management and Development - Queensland

Location map of Cressbrook Creek

Groundwater Management Unit: Cressbrook Creek

Introduction

Management Context:

The issue of low groundwater levels near Toogoolawah was addressed in 1997 with construction of the Lower Cressbrook Weir. Due to the situation of the Cressbrook Dam, the lower Cressbrook Creek experiences fewer large flows. To compensate for loss of natural flow, controlled releases from the dam are made. Aquifers downstream however were not kept wet for a significant time. Installation of the Lower Cressbrook regulating weir has successfully raised groundwater levels near Toogoolawah. A proposal to build five additional small recharge weirs between Toogoolawah and Brisbane River is currently being considered.

Improved monitoring and assessment of water releases, from the Cressbrook Dam and the weir storage areas, are also needed to understand what proportions of water are diverted downstream.

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

 NO

Defined Minimum Water Level

 NO

Comment: With the exception of low groundwater levels near Toogoolawah no significant issues are reported in the Cressbrook Creek GMU.

Comments on Management Responses

2020 Management Response:

A maximum forecast use estimate of 3800 Ml/yr in the year 2020 is based upon the sustainable yield and desired level of management in the GMU.

2050 Management Response:

A maximum forecast use estimate of 3800 Ml/yr in the year 2050 is based upon the sustainable yield and desired level of management in the GMU.

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

Assessment of monitoring in Cressbrook Creek

Efficacy of the network:

The current monitoring network in the Cressbrook Creek groundwater management unit consists of 28 observation bores with a proposed quarterly monitoring frequency. Water level and quality monitoring is ongoing since the early 1960s. The salinity monitoring network is however very limited.

Data management requirements:

Queensland groundwater monitoring data, including 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 licences. However the GMU has no groundwater allocations.

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:

Construction of Cressbrook Dam in 1983 in the headwaters of Cressbrook Creek was to the detriment of downstream users around Toogoolawah. To compensate for this reduction in natural flows, a release strategy was formulated for the Cressbrook Dam. On an agreement between Toowoomba City Council and the Water Resources Commission the strategy resulted in volumes between 1375 and 2750 Ml/yr being released form the Cressbrook Dam.

Continued discussion with Toowoomba City Council on the release policy is required to determine if the current policy meets the objective of maintaining yields at a pre- Cressbrook Dam level.

Options for monitoring:

If construction of five small recharge weirs between Toogoolawah and Brisbane River is approved, the monitoring network will require upgrading to monitor groundwater levels and quality around the sites. Work has been done to upgrade the current water quality monitoring network but there has been no major commitment to its improvement.

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: 

The sustainable groundwater yield of the Cressbrook Creek GMU has been evaluated on four separate occasions. Bases on assessment of these evaluations a figure of 3800 Ml/yr has been adopted as the sustainable yield prior to the construction of Cressbrook Dam.

Sustainable yield:

ML/yr

Threshold year for sustainable year:

2,020 

Abstraction Volume 1996/1997:

2,924 ML 

Current Resource development categorisation:

Estimated Use in 2020

Comment:

Estimated use in 2020:

3,800 ML 

% change from 1996/1997:

30 

Resource development categorisation:

Estimated in 2050

Comment:

Estimated use in 2050:

3,800 ML 

% change from 1996/1997:

30 

Resource development categorisation:

 

What assumptions were used in this assessment

Development Potential:

The water resource of the Cressbrook Creek GMU is currently highly developed with little plans for additional work. The area is soon to be handed from State Water Projects to Resource Management.

Estimate of Use:

A maximum forecast use estimate of 3800 Ml/yr in the years 2020 and 2050 is based upon the sustainable yield and desired level of management in the GMU.

Data Availability,Gaps and Recommendations

Data Availablility:

Groundwater level monitoring is conducted in a network of 28 observation bores. Recharge is monitored via groundwater level monitoring along various sections of creeks and weir storage areas. Water quality monitoring consists of a basic salinity recording network with post-1990 data for 32 bores.

Current Gaps and Recommendations:

Data Gaps: The salinity monitoring network is very basic in the Cressbrook Creek GMU. Work has been done to upgrade monitoring but there has been no major commitment to its improvement.

Recommendations: No recommendations have been made to address data gaps in the GMU with the exception of maintaining the existing commitment.

Future Gaps:

Further gauging should be administered on the downstream side of the Cressbrook Creek Weir storage area, to quantify the volume of water leaving the weir, and an automatic water level recorder should be installed to effect an accurate water balance on the weir.

If construction of five small recharge weirs between Toogoolawah and Brisbane River is approved, the monitoring network will require upgrading to monitor groundwater levels and quality around the sites.

Further information

Key

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