The Dartmouth Dam (NSW) has remained at approximately 99% capacity since August and now the Murray-Darling Basin Authority has announced that a spill is to be expected, for the first time this century.
The Dartmouth Dam is the largest water storage in the MDB, with the capacity to hold over 3.8 million Megaliters, more than 40% of the River Murray’s total storage capacity. If a spill of the water storage does occur, this will have a flow on effect, causing higher flows along the Mitta Mitta system and reaching the Hume Dam about 1 day later.
This could cause further spilling of the Hume Dam, which has been releasing water at a rate of over 30GL per day since the beginning of August. On 21 September 2022 the Hume dam was at 97% capacity and the Murray Darling Basin as a whole is at 98% capacity.
If Dartmouth Dam spills, this will be the 5th time since 1979 that this dam has spilt water.
The Dartmouth and Hume dams are cooperatively owned and store allocation water for both New South Wales and Victoria. With both of these dams effectively full it will have the continued effect on the following:
- Long Term Lease Market
- Softened prices on the temporary market have resulted in Long-term Lease prices softening too, creating a great opportunity for those looking to secure entitlement for the next 3 - 5 years
- For Example, SA Class 3 was valued at approximately $4000 per ML in 2016 and now its $8,200 per ML. What will it be in another 5 years time and how will this affect lease prices?
- Victorian Spill Accounts
- 100% of water in Victorian spill accounts has been lost.
- Additional water in the system water carried over on Low Reliability license could also be lost and replaced with allocation water for the 2nd consecutive season
- NSW to Vic trade restriction
- With both storages full there isn’t enough room to transfer water from one state to another
- NSW interstate trade restriction
- With full storages WaterNSW aren’t accepting any interstate trades into Murray, Murrumbidgee and Lower Darling systems
- i.e. No water can be traded into NSW
- With full storages WaterNSW aren’t accepting any interstate trades into Murray, Murrumbidgee and Lower Darling systems
- Flooding
- More rain and spilling increase the chances of flooding downstream of Dartmouth Dam impacting local communities and irrigators. This could also occur downstream of Hume Dam
This imminent spillage comes in conjunction with the Bureau of Meteorology declaring a 3rd consecutive La Niña weather event (read more here) and a Negative Indian Ocean Dipole bringing more rainfall to storages and farmlands.
With more rain and water available in the system, prices in the temporary market are expected to lower
In the previous season, water in the allocation market lowered to prices not seen since the 2016/17 season due to the vast amounts of water available and with even more water available it is reasonable to expect that the same could happen again.
If you would like to know more about how this will affect you and your entitlement, please contact your local water account manager on 1800 890 285
