2024/25 opening seasonal determinations and risk of spill update

The Resource Manager for northern Victoria today announced the first 2024/25 seasonal determinations, an updated determination outlook, and the initial risk of spill in the Murray, Goulburn and Campaspe systems.

The Murray system starts 2024/25 with a seasonal determination of 63 per cent of high-reliability water shares (HRWS). The Goulburn and Loddon systems begin with 69 per cent HRWS.

The Campaspe system starts 2024/25 with 100 per cent HRWS. The Broken system opens with 5 per cent HRWS and the Bullarook system starts the year with 0 per cent HRWS.

Resource Manager Mark Bailey said the opening seasonal determinations reflected reserve availability across the systems.

“Reserves secured during 2023/24 have underwritten the opening seasonal determinations in the Murray, Goulburn, Campaspe and Loddon systems,” Dr Bailey said.

“The storages in these systems are holding large volumes despite recent months of below-average rainfall.

“Growth in the seasonal determinations in the Broken and Bullarook systems will depend on rainfall and resulting catchment flows during the early months of the water year.”

Noting the recent weather aligned with a dry outlook scenario, Dr Bailey said the latest Bureau of Meteorology outlook favoured slightly below-average rainfall between July and September.

“The risk of spill in the Murray system is 85 per cent and 80 per cent in the Goulburn system,” Dr Bailey said.

“In the Campaspe system, the risk of spill from Lake Eppalock is about 70 per cent.

“The risks have fallen since the last update, consistent with below-average storage flows in May and June.”

Dr Bailey said the risk of spill assessment did not describe the chances of flooding this season.

“The risk of spill is a water accounting assessment. It does not refer to flood risks downstream of the storages.”

Outlook for the 2024/25 Season

The outlooks for 2024/25 seasonal determinations are based on historical flow records that have been adjusted to match climate conditions observed since 1975. The outlook scenarios presented are:

• Wet                  Inflow volumes to major storages that are greater in 10 years out of 100
• Average          Inflow volumes to major storages that are greater in 50 years out of 100
• Dry                  Inflow volumes to major storages that are greater in 90 years out of 100
• Extreme Dry   Inflow volumes to major storages that are greater in 99 years out of 100

The following tables summarise possible high-reliability water share seasonal determinations through the season and include a reference year to help users recognise the possible inflow conditions.

Murray System Outlook for Seasonal Determination of High-Reliability Water Shares

Goulburn and Loddon System Outlook for Seasonal Determination of High-Reliability Water Shares

Broken System Outlook for Seasonal Determination of High-Reliability Water Shares

Bullarook System Outlook for Seasonal Determination of High-Reliability Water Shares

Seasonal determinations under additional scenarios for each system are available from the Northern Victorian Resource Manager website at www.nvrm.net.au/outlooks

Upcoming Resource Manager announcements

• The risk of spill in the Murray, Goulburn and Campaspe systems will be updated on Wednesday 10 July, 2024.
• The next 2024/25 seasonal determination announcement will be released on Monday 15 July, 2024 and will include an updated outlook.