Padthaway Water Allocation Plan review and amendment

Review and amendment of the Padthaway Water Allocation Plan

In 2025 a revised Padthaway Water Allocation Plan was adopted and implemented. The revised plan was a result of a review and amendment process that commenced in 2019. A Stakeholder Advisory Group, stakeholder consultation and the best available science supported the process.

Review of the Padthaway Water Allocation Plan

In 2019 a comprehensive review of the Padthaway Water Allocation Plan (the Plan) was undertaken.

The review process concluded that the Plan was working well and the resource was in good condition. Groundwater levels were generally stable and current allocations were adequate and equitable. Supported by the Stakeholder Advisory Group the process also concluded that the operation of the Plan should stay the same where possible.

While groundwater levels were generally stable, groundwater salinity trends were variable. Wells displayed decreasing, stable and increasing trends. A range of different drivers underpin these variable trends. Modelling was used to explore salinity trends and address potential impacts from extraction.

The review process identified that some matters needed to change to improve alignment with the Landscape South Australia Act 2019. These were:

• defining consumptive pools
• partial unbundling of the licensing instruments
• introducing an adaptive management framework
• furthering recognition of First Nations connections to water.

The next comprehensive review of the Padthaway Water Allocation Plan needs to occur by 2035.

Amendment of the Padthaway Water Allocation Plan

Defining consumptive pools

The revised Padthaway Water Allocation Plan has three consumptive pools. They are the:

• Padthaway Unconfined Aquifer Consumptive Pool. The value of all entitlement shares available for allocation within the pool is 56,668,741 kL/y.
• The Padthaway Confined Aquifer Consumptive Pool. The value of all entitlement shares available for allocation within the pool is 0 kL/y.
• The Padthaway Managed Aquifer Recharge Consumptive Pool. The water available for allocation as a result of metered drain and discharge activities in the unconfined aquifer.

The revised Padthaway Water Allocation Plan has also established two separate management zones, equivalent to the past management areas. They relate to the Padthaway Unconfined Aquifer Consumptive Pool to manage resource condition and impacts associated with the take, extraction or use of water:

• Padthaway Flats Management Zone. The value of all entitlement shares available for allocation within the consumptive pool is 54,951,538 kL/y.
• Padthaway Range Management Zone. The value of all entitlement shares available for allocation within the consumptive pool is 1,717,203 kL/y.

These management zones also relate to the Padthaway Managed Aquifer Recharge Consumptive Pool. Any water allocated to this consumptive pool will be the result of metered drain and discharge activities in the unconfined aquifer.

Partial unbundling of the licensing instruments

The amendment process introduced two water licencing instruments:

• Water access entitlement. This gives the holder a right to a share of water in a specified consumptive pool. Each water share is equivalent to 1 kilolitre (kL). Each water access entitlement is allocated a class which describes permitted water uses.
• Water allocation. The actual volume of water from the water access entitlement that can be extracted for use each year. Water allocations are reviewed annually and an allocation will be set for each water use year (July 1 to June 30).

The Plan will continue to allow licensees to apply to carryover an unused water allocation into the next water use year. This applies to water used for irrigation, recreation, industry or public water supply.

Classes of water access entitlement introduced in the revised plan are:

• Class Ta. The tradeable irrigation component used for any purpose.
• Class Tb. The tradeable industrial and recreation components used for these purposes only.
• Class P. The tradeable public water supply used for this purpose only.
• Class D. The delivery supplement (DS) component for flood irrigation licences used for this purpose.
• Class S. The specialised production requirements (SPR) component used for this purpose only.
• Class Ra. Desalinised groundwater that has been injected or drained into the aquifer through managed aquifer recharge.
• Class Rb. Surface water that has been injected or drained into the aquifer through managed aquifer recharge.

Introducing an adaptive management framework

The Plan defines groundwater levels that if reached will trigger management actions. These actions prevent adverse, long-term impacts on water resources, water users and the environment. By responding when these resource condition triggers are reached, further deterioration of the resource is avoided. This approach allows the Padthaway community and stakeholders the opportunity to self-regulate and manage their water use within acceptable limits.

The resource condition limit is a threshold that indicates that there is an unacceptable level of risk. This risk is to economic, social and environmental values dependent on the water resource. The resource condition limit was set at the lowest recorded water level (July 2009) for the area. This was selected in collaboration with the community as conditions that they remembered and that represented an undesirable state. Many experienced declining yields, stock and domestic wells and licensees were still able to operate. Environmental assets that experienced these conditions were sustained and recovered under improved conditions.

As this threshold indicates an unacceptable risk it triggers a restriction of allocation to the acceptable level of extraction (ALE) of 48,000 ML/y. The acceptable level of extraction halts and reverses the resource decline. It can recover levels above the resource condition limit. The groundwater model also demonstrated that the acceptable level of extraction maintains the hydraulic gradient. This is critical to maintaining the through flow of fresher water in the Padthaway Range. This flushes higher salinity water out of the Padthaway Prescribed Wells Area.

The resource management threshold has been set at a level where the groundwater resource is at significant risk and is not recoverable with the provisions in the Plan. It prompts the Limestone Coast Landscape Board to begin an early review and amendment of the plan.

Targeted monitoring of the groundwater resources evaluates the status and condition. It is critical to the effectiveness of the adaptive management approach. The adaptive management framework is an effective means of managing the resource in a changing climate.

Furthering recognition of First Nations connections to water

Part of revising the Padthaway Water Allocation Plan was furthering the recognition of First Nations connections to water. First Nations peoples of the Limestone Coast have been living and caring for this country for over 60,000 years. The South East Aboriginal Focus Group, the traditional custodians of the South East of South Australia, have been working closely with the Limestone Coast Landscape Board, and its predecessors, since 2004, sharing knowledge and culture.

We are walking with First Nations to incorporate strategies to achieve First Nations objectives. We are committed to a continuing relationship of shared learning through Lartara-Wirkeri Cultural Governance. We share knowledge on water management and collaborate on cultural water through ‘on-country’ workshops and meetings.

We will work with First Nations throughout the life of the Plan. We will better understand connections to landscape and establish cultural objectives. We will incorporate monitoring and evaluation to assess if cultural values are being sustained and cultural objectives achieved.

We will meet annually with the South East Aboriginal Focus Group to discuss resource condition and how well the Plan is working.