Horticulturists and agriculturists who take water from aquifers in the Gingin groundwater area south of Gingin Brook and Moore River will have any reductions to their entitlements delayed, according to the Gnangara groundwater allocation plan.

On the southern side of Gingin Brook and Moore River, groundwater from the Gnangara groundwater system is used to grow pasture, fruit, vegetables, nursery plants and turf.

According to the Department of Water and Environmental Regulation (DWER) about 14 GL a year across almost 100 licences is abstracted in the Gingin area.

In a section of the plan outlining exemptions DWER said any reductions to groundwater entitlements from the superficial and Leederville aquifers in the Guilderton South, Beermullah Plain South, Deepwater Lagoon South and SA3 South sub-areas would be delayed until a new Gingin water allocation plan was completed.

“This is because groundwater abstraction on both sides of Gingin Brook and the Moore River Estuary influences the flow and health of these systems and they need to be considered together,’’ DWER said.

During the consultation period for the Gnangara groundwater allocation plan one respondent raised concerns there would not be enough water available in Gingin to support an increased demand in food production.

DWER said as reduced rainfall due to climate change continued to reduce groundwater availability, demand for water would need to come from water trading, transfers, greater water use efficiency and water savings, or from alternative sources (other than groundwater).

Several respondents also pointed out that some neighbouring farmers – including in the Gingin area either side of the northern plan boundary – would be subject to reductions and some would not.

DWER said the second-largest amount of groundwater taken from the Gnangara groundwater system was for agriculture with about 61.9 GL a year, mostly from the shallow superficial aquifer, used to provide fresh local produce and export income.

Under the adopted plan agricultural water users in the North Wanneroo, East Wanneroo and the Swan Valley except for established commercial nurseries and tree farms will need to reduce their groundwater abstraction by 10 per cent from 2028, the same percentage as other self-supply licensees.

The Gnangara groundwater allocation plan said local abstraction, together with climate change and regional scale abstraction from the deeper aquifers, had reduced flows in Gingin Brook and negatively affected wetlands and groundwater-dependent banksias in the area.

“Local groundwater-level declines vary but 1m to 2m declines during the past decade have been common,’’ DWER said.

“As part of this plan, we are signalling our intent to reduce groundwater abstraction in the Gingin area.

“However, we will not reduce licensed abstraction until we confirm an approach in a new Gingin water allocation plan.’’

But water licences in the Lake Mungala sub-area (superficial aquifer) will be subject to the reductions outlined in this plan.

“This is because abstraction in this area does not affect flows in Gingin Brook and won’t be included in the new Gingin water allocation plan.

“We will establish a comprehensive and fair approach to managing the values of Gingin Brook and Moore River Estuary in the new Gingin water allocation plan, which we are aiming to complete by 2025.”

The new plan will combine and replace both the Gingin groundwater allocation plan (DoW 2015) and the Gingin surface water allocation plan (DoW 2011).

The City of Wanneroo is calling for industry exemptions outlined in the McGowan Government’s plan to rebalance Perth’s northern groundwater resources to be extended to include the food production industry.

This article appeared on Yanchep News Online on 12 June 2022.