Drought, heat and wind: Why west Vic’s dams are staying low despite the rain

“Even in Dad’s time, he’s never seen it as dry as this.”

Jamie Pepper has spent 15 years working on his family’s fourth-generation sheep and beef farm in Tahara, west of Hamilton. And despite a promising spring, many of the property’s roughly 20 dams remain low.

🪾 On the ground: Pepper described to the Brolga how the drought, combined with high summer and autumn temperatures and relentless wind, have intensified evaporation from his water storages.

• “The wind just seemed to keep coming, and it basically dried the whole country out as soon as [the rain] fell,” said Pepper.

💰 Investment a must: To cope with the change, Pepper and his family have spent nearly $100,000 on piping, tanks, pumps, and trough networks to shift water across the farm and keep stock supplied.

• Even with these measures, some dams are “artificially full” only because water is being siphoned constantly from a spring, Pepper said. 

• “Daily checking, moving the pipe when required… it does take a lot of time and energy.”

💧 Why dams aren’t filling: Experts say dams not filling is not unusual given the region’s soil conditions and rainfall patterns. 

Dr Keirnan Fowler, Senior Lecturer in Hydrology and Water Resources at Melbourne University, explained that dry soils act like a sponge, absorbing rainfall before it can reach dams or streams. 

• “Just because it rains, it doesn’t automatically lead to streamflow for our dams. It depends on how dry the soil is,” said Fowler.

Agriculture Victoria notes that, under current conditions, rainfall events typically need to exceed 20mm to “generate runoff into storages”. If your grass height is over 50mm, you may need 60mm or more per event.

• As Pepper has experienced on his farm, wind has the biggest effect on evaporation. Even in good seasons, dams can lose up to 0.75m of water, often half their volume.

📈 Long-term trends: Victoria’s 2023 and 2024 Annual Water Outlook reports show that “cooler-month rainfall is declining”, while temperatures and evaporation rise. 

• Catchments are now producing less streamflow for the same amount of rain than they did a generation ago.

• Rising greenhouse gas concentrations caused by the burning of fossil fuels like coal and gas are altering the weather systems that historically delivered much of Victoria’s runoff, meaning less water will reach dams even when it rains.

🪣 Managing water on farms: Agriculture Victoria is encouraging farmers to measure and manage their storage levels ahead of summer. 

It suggests farmers:

• Track how much water stock may be drinking and get a gauge on how much water may be lost through evaporation or leakage, and identify which is having the greatest impact.

• Understand that while solutions such as dam covers or enlargements exist, they can be costly and technically difficult. 

• Look into low-cost strategies like piping, trough networks, or combining smaller storages can help retain water and maintain stock supply.

🌧️ Preparing for the future: For Pepper, the adaptations have been costly but necessary. “We were forced to do it, or we would have had to de-stock,” he said. 

Despite the effort, he sees silver linings: the farm is now better prepared for dry spells, water management has improved, and the lessons learned will help the family face future challenges.