Capacity of groundwater resources - Peake, Roby and Sherlock Prescribed Wells Area

  • Fact sheet
  • August 2015
General schematic of the drawdown within the confined aquifer
General schematic of the drawdown within the confined aquifer

This document explains what has been considered when setting the volume of water that may be extracted from the groundwater in the Peake, Roby and Sherlock Prescribed Wells Area (PRS PWA).

Determining extraction limits

Our groundwater resource has many users, environmental, social and economic. In order to manage the resource for current and future users, it is important to balance the needs of all users. Assessment of the capacity of the groundwater resource to meet the current and future water needs of the environment, businesses, stock and people, takes into account the impact of:

Due to the nature of the aquifers in the PRS PWA, if extractions are too large the pressure level for the confined aquifer may fall below the confining layer, and possibly even below the top of the confined aquifer itself.

This depressurisation could lead to the confining layer above the aquifer drying out, and ultimately to fracturing, and leakage from the overlying unconfined aquifer into the confined aquifer.

Groundwater extraction for major use, such as irrigation, can cause groundwater pressures to fall. This can have an impact on stock and domestic users.

The extraction limit is an acceptable volume of extraction per year for irrigators and stock and domestic users. It must be recognised that all groundwater extraction will have an impact on the groundwater system, especially in a confined aquifer.

Effects of water taking on the groundwater resource

A groundwater resource condition indicator is a measurable groundwater parameter such as groundwater pressure, drawdown, or groundwater salinity.

The Water Allocation Plan for the PRS PWA (2011) contains principles that state the thresholds that should be monitored and not exceeded. These principles state that the taking of underground water must not cause or have the potential to cause:

Should any of the above occur, the consequences set out in principle 29 (refer WAP 2011) will apply.

Table 1

Underground water level observation wells, threshold water levels and corresponding static water levels

Well   Maximum measured water level elevation  Minimum measured water level elevation

mAHD* 

SWL(m)** 

mAHD* 

SWL(m)** 

SHK004  6.5  12  4.4  14.1
PEK007  5.3  15.4  10.0  30.0
PEK005   5.4  13.1  0.4  18.1
RBY014  5.0  10.5  3.2  12.3
RBY017   4.7  16.0  1.7  19.0

*mAHD stands for ‘metres above the Australian Height Datum (AHD)

AHD is approximately mean sea level

**SWL stands for ‘static (or standing) water level’, or the distance from ground surface to the static water level

Table 2

Underground water salinity observation wells and corresponding baseline salinity levels 

Well  Baseline salinity levels
(mg/L
)
PEK006

1980

RBY017 

 3570

RBY020

 4740

RBY024 

 4023

RBY027

 3194

The indicators and values reflect a balance of economic development, protection of the resource and rights of stock and domestic users. Consideration was given to the issue of how to deal with long-term climate variability.

More information

Refer to the related links below for the WAP 2011, and other detailed information on the PRS PWA water planning page of our website.

We have also developed a range of factsheets about water allocation planning and licensing to assist you with managing your water resources. See the related links below.

Related links