Available water determinations for groundwater

At the start of each water year on 1 July we announce available water determinations for groundwater. An available water determination allocates water to licensed groundwater users. Water access licences authorise a licence holder to take water from a particular groundwater source. The licence holder receives their water allocation upon an available water determination announcement.

Allocation of groundwater

An available water determination allocates water to a category of access licence. There are various categories of access licence. For example, town water supply or aquifer access licences. Each water access licence has a water allocation account. An available water determination adds, or credits, water to the water allocation account. Physical take of water subtracts, or debits, water from the water allocation account.

Available water determinations add water to water allocation accounts. Each category of access licence has a water allocation account

On 1 July, licensed users receive an opening allocation for each licence category. This may be anywhere between 0% and 100% of their entitlement. The volume of water a licence holder can extract each year is set by the water sharing plan rules.

Water sharing plan limits and compliance triggers

Water sharing plans set a long-term average annual extraction limit for each groundwater source. These limits are measured on a rolling average annual basis. This means that in some years licence holders can pump higher volumes than the annual limit. Water sharing plan rules set time limits on how long this can continue.

Water sharing plans state how to manage compliance with extraction limits. This varies between plans. There is usually a 5% or 10% exceedance level above the plan’s limit, which we call the compliance trigger. We measure average annual extraction using either a three- or five-year rolling period. Then we apply the compliance trigger.

If the rolling average goes over the compliance trigger, we may announce a reduced available water determination in the following water year. This is necessary to return extraction to within the plan’s limit. This means that licence holders will not receive their full entitlement.

Available water determination assessment

We consider a range of factors when determining the allocation of water to users. Before 1 July, we check the rolling average annual extraction against the plan’s limit for compliance. When the rolling average annual extraction exceeds the compliance trigger in a groundwater source, we must reduce the available water determination.

Figure 2 shows the rolling average annual extraction tracked against the plan’s limit and the compliance trigger. In this case, it is a five-year rolling average and a 5% compliance trigger.

Five-year average annual extraction exceeds the extraction limit plus the compliance trigger, leading to reduced available water determinations

Our assessment considers many factors. Download our fact sheet PDF, 298.7 KB for more information on available water determination assessment.

Available water determination announcements

We announce available water determinations on our website. After announcing an available water determination, we credit water allocation accounts as advised in the determination.