December 2019 Summary
Rainfall was very much below average, including lowest on record, across 67 per cent of the area mainly in the north. Mean rainfall was 6 mm, 88 per cent lower than the long-term mean of 48 mm for December and was the second lowest in the past 120 years.
Streamflows were very much below average including lowest on record for 50 per cent of the sites. Streamflows were the lowest for December since 1980 for eleven sites located in the northern part of the drainage division and one site in the southern part.
Streamflows were fresh or high-quality for 86 per cent of the sites. Median streamflow salinity (electrical conductivity) varied between sites from 45 to 3041 μS/cm. Billabong Creek at Walbundrie had the highest salinity of all reporting sites.
By the end of December, the volume of water stored was 29 per cent of the total accessible capacity, a decrease of 13 per cent from the previous year. During December, accessible storage volumes decreased in 12 systems and remained stable in six. The storages in the northern Murray–Darling Basin remained extremely low, having received no significant inflows in December leaving the total accessible volume of the Namoi at 2.3 per cent, Border Rivers at 3.3 per cent, Gwydir at 6.3 per cent and Macquarie-Castlereagh at 8.3 per cent.
|Rainfall decile group||Percentage of area|
|Highest on record since 1900||0%|
|Very much above average||0%|
|Average||Less than 1%|
|Very much below average||63%|
|Lowest on record since 1900||4%|
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