LAST December Snowy Hydro dumped water into the already flooded Murray-Darling, but said it had little choice. A report just released by the NSW Office of Water clears Snowy Hydro but only in so much as it states that Snowy Hydro operated in accordance with its licence conditions.
At issue has always been whether these licence conditions were fair both to Snowy Hydro and those living and working in the Tumut and along the Murrumbidgee. In particular did Snowy Hydro’s licence conditions, as enforced by the NSW Office of Water, oblige Snowy Hydro to make releases that contributed to the flooding?
According to the detail in the substance of the report:
The rainfall during 2010/11 also triggered repayment of water borrowed from the Snowy Scheme by irrigators in the Murrumbidgee Valley. This water was “borrowed” by individual irrigators, primarily in 2005, to supplement the very low allocations that were being experienced at that time.
These borrow arrangements generally involved Snowy Hydro agreeing to release more than RAR [Required Annual Release], which was then allocated to the individual irrigation participants in that year. The “borrowed” water was to be repaid by the participants to Snowy Hydro when certain allocation triggers were met.
In the Murrumbidgee Valley repayment was to commence when announced water allocations reached 50 per cent. The effect of these repayments is that the RAR for the Snowy-Tumut Development was reduced by the volume of water repaid, which was ultimately the full outstanding balance of the borrows being 204 GL. General Security water allocations reached 100 per cent in the Murrumbidgee Valley on 15 December 2010 and it was only at that point that it became certain that the full amount of the borrowed water would be repaid…
By the end of November 2010 the releases made by Snowy Hydro for the purposes of meeting its RAR [Required Annual Release] requirements were 785 GL. This occurred over seven months at an average monthly release rate of 112.14 GL.
As it was not possible at this time to assume full repayment of the borrowed water, the RAR for the full year was 1423 GL assuming full repayment of the DISV. This would mean a residual requirement to make releases of 638 GL. If no releases were made towards the RAR in December the required average releases for each of the last four months of the water year would be 159.5 GL.
Snowy Hydro’s assessment that making releases towards the RAR in December 2010 would have been problematic is reasonable for the following reasons:
• The forecast was for continuing wet conditions in the beginning of the 2011 calendar year. For the reasons discussed in Part 4.4.3 this may have restricted Snowy Hydro’s abilities to make releases from Jounama Dam.
• When Lake Eucumbene is at less than full capacity there are reductions in the capacity of the Tumut Pondage – Eucumbene-Tumut Tunnel that may have hindered releases of the required quantum being made.
Clause 13 of the licence allows the Office of Water and Snowy Hydro to, in any water year, agree to a reduced RAR. As inflows increased from September, the Office of Water and Snowy Hydro commenced discussions to reduce the RAR for 2010/11 to enable releases through the Snowy-Tumut Development to be reduced. Following the flooding a limited reduction to the RAR was agreed on 23 December 2010.”
So, up until 23 December 2010, was Snowy Hydro making releases into the already flooded Murray Darling at least in part because of obligations under its licence agreement with the Office of Water?
The report concludes that: “Overall the various agencies worked effectively together to manage inflows and releases from dams that assisted in mitigating the height and extent of flooding downstream.”
But this is not evident from the detail provided in the same report.
Links and references:
A series of blog posts on the issue are here, scroll down for the full list:
The NSW Office of Water review document can be downloaded here: