Padthaway Water Allocation Plan

Objectives of the Padthaway Water Allocation Plan

The objectives of the Padthaway Water Allocation Plan are to license, allocate and manage water in a manner which:

• Provides security of water access entitlements to users of the resource.
• Minimises the impact of taking water on the resource, other water resources, groundwater dependent ecosystems and existing users.
• Manages the resources within acceptable resource condition limits to maintain economic, environmental and social needs.
• Maintains groundwater dependent ecosystems at a low level of risk.
• Maintains the cultural values and needs of First Nations people.

The guiding principles are to:

• Manage the water resources of the unconfined aquifer so that they continue to be available for the social, economic, environmental and cultural needs of current and future generations.
• Protect the resource locally, in each management zone and the entire area.
• Provide flexibility and equity in access to the water resource of the unconfined aquifer.
• Recognise and incorporate the traditional knowledge of First Nations people in the management of the resource and groundwater dependent ecosystems.
• Maintain the availability of water to groundwater dependent ecosystems.
• Protect the environment by ensuring that the taking and use of water from the unconfined aquifer does not cause significant degradation of any other resource e.g. soils.
• Provide principles so that water allocations are available to sustain economic development.
• Allow the Padthaway community and stakeholders the opportunity to self-regulate and manage their water use within acceptable limits.

Water resources in the Padthaway Prescribed Wells Area

Water resources in the area consist of an unconfined aquifer and a confined aquifer. The upper unconfined aquifer is recharged through rainfall. A thick clay sits under the unconfined aquifer preventing recharge into the confined aquifer and connectivity between the aquifers.

The Padthaway Prescribed Wells Area supports just over 100 water licences.

Water resource in the unconfined aquifer

The unconfined aquifer is the primary water resource used in the area for public water supply, irrigation, recreation and industry. The unconfined aquifer is fully allocated. It is divided into two management zones, the Padthaway Flats and Padthaway Ranges.

Groundwater flows in a west to north-west direction from the Naracoorte Range, towards and along the flats in the west. The unconfined aquifer in the flats area generally has high well yields. Depth to water tends to range between two and six metres.

The unconfined aquifer in the ranges area to the east tends to have lower well yields and can produce fine sand when pumped.

Salinity in the Padthaway Prescribed Wells Area in the unconfined aquifer

Groundwater salinity trends are variable across the Padthaway Prescribed Wells Area. Some wells have shown declining or stable salinity trends whilst others have displayed an increasing salinity trend. Increasing trends in groundwater salinity are a combination of processes, including:

• Clearance of native vegetation between the 1950s and 1970s. This resulted in the flushing of salts from the unsaturated zone in the Padthaway Range. The natural underground water flow has mobilised this historic salt load into the Padthaway Flats.
• Evaporation and drainage of irrigation water (irrigation re-cycling) under flood irrigation.
• Flushing of high salinity soil under drip and pivot irrigation during periods of high rainfall.
• Evapotranspiration of groundwater where the water table is shallow.

The groundwater salinity in the Padthaway Flats ranges from 1,700 μS/cm to 3,700 μS/cm. It becomes far more saline (7,800 μS/cm to 15,800 μS/cm) toward the western margins.

The groundwater salinity in the Padthaway Range is generally lower than in the Padthaway Flats. Salinity ranges from 1,800 μS/cm to 3,100 μS/cm.

A changing climate and the Padthaway Prescribed Wells Area

Climate is the primary driver of trends in groundwater levels in the Padthaway Prescribed Wells Area. This is especially evident in the Padthaway Flats. Historical groundwater levels show seasonal fluctuations of up to 2 m in the Padthaway Flats. In the Padthaway Ranges groundwater water levels are more consistent.

The Padthaway Water Allocation Plan has an adaptive management framework to respond to a changing climate. This allows for transparent management responses if the resource condition declines. Development of the adaptive management framework used a groundwater model, stock and domestic well vulnerability analysis and community knowledge and input.

History of the Padthaway Water Allocation Plan

The current version of the Water Allocation Plan for the Padthaway Prescribed Wells Area was adopted on 20 May 2025.

It replaced the Padthaway Water Allocation Plan that was adopted 26 April 2009. The first Padthaway Water Allocation Plan was adopted on 14 October 2001.

Find out more about the review and amendment process to create the Padthaway Water Allocation Plan 2025