Cobar Water Supply September 2019

The Situation

The Cobar population is 3,990 (2018 Census) with a few hundred pastoralists and miners beyond the urban area. Cobar obtains its water from the Burrendong Dam, 390 km to the south-east. Water restrictions are in force and it is assumed water consumption is encouraged to be around 150 L/p/d, that is 598,000 litres – say 600,000 litres per day (0.6 ML) or 220 ML/year. This is in line with other regional centres experiencing water shortage.

The 2017-18 Water Report released by Cobar Shire Council summarises water consumption under its jurisdiction:

Distribution Mega Litres
Cobar Shire Council  (1) 1395
Peak Gold Mine                           474
Endeavour Mining 726
Cobar Management  (2) 933
Minor Consumers (3)  60
Total (4)                         3588
Pumped from Nyngan Weir (5)                         4034

1 Cobar Shire Council data includes consumption for domestic, business, agriculture and industrial users. With an estimated domestic consumption of 220 ML/year, other consumers aggregate 1175 ML/year.

2 Cobar Management – this is water supplied to the CSA Mine. 

3 Minor Consumers – users obtaining water along the Nyngan-Cobar pipeline.

4 The difference between 4 and 5 is 446 ML – water loss/other users?  

Cobar Water Supply

The town water supply is obtained from the Burrendong Dam, 390 km south-east of Cobar. From the dam water is pumped 190 km to Warren on the Macquarie river then along the 75 km open Albert Priest Channel to the Nyngan weir pools; finally by pipeline for 130 km to the Fort Bourke filtration plant in Cobar.

The Burrendong Dam has a capacity of 1,188,000 ML but, due to drought, capacity has reduced to 4.6% (54,608 ML) and declining. Currently water is being released at 150 ML/day equivalent to 34,750 ML/year. This is a serious situation since current capacity is 54,608 ML and falling. Without rain the dam will be empty before mid 2020. On 16th September on ABC AM, the Deputy Prime Minister warned that the dam upon which Dubbo relies, could be effectively out of water by year end.

The Cobar allocation from Burrendong Dam has been reduced from 3,588 ML (2018) to 1,850 ML/year, equivalent to 5.1 ML/day. Daily release from the Burrendong dam is currently 150 ML/day. Working on a drought allowance of 150 L/p/d the daily distribution in mega litres might be Cobar 5 (includes industry etc), Dubbo 11 with the balance of 136 applied to industry, irrigation and other rural settlements.,  With water restrictions in force and the Cobar population consuming 150 L/p/d this equates to 0.6 ML/day, which permits 4.5 ML/day for agricultural industrial use. Domestic consumption appears to be in line with Tenterfield and Orange.

History Ancient and Modern

Cobar has no natural water supply. With the discovery of copper in 1869 water has remained a critical problem. Initial supplies were from a small earth dam. Later in-ground tanks were constructed that were filled from local runoff. In 1942, the Albert Priest Open Channel was constructed from Warren on the Macquarie River to the Nyngan Weir Pools. Water was then freighted by rail to Cobar. A 131 km pipeline to Louth on the Darling River was mooted but rejected. A modern water supply was completed in 1963 with the construction of a 300 mm pipeline between Nyngan and Cobar. This was expanded by the addition of a 375 mm pipeline a few years later. The system operates under the Cobar Water Supply Act 1963. Corrosion has developed in the 300 mm line and a $10 million repair and upgrade of the Nyngan storage weirs is planned.

The Cobar Shire has recently circulated a plan, “Nyngan Cobar Water Security Paper’, recommending replacement of the open Albert Priest Channel by a pipeline with a project cost of $70 million. There are concerns by the irrigation industry in Nyngan Shire that it would be disadvantaged if this plan is adopted.

Future Development Restrictions

The Cobar Shire Council has advised that, under the provisions of the Water Management Act 2000, water allocations to Cobar from the Burrendong Dam cannot be increased to service expanding industry or mining activity. New water requirements must be purchased from existing license holders. This policy has the potential to inhibit population and economic growth throughout the Central West and north to the Queensland Granite Belt.

Mining companies operating round Cobar have been warned by the Shire they may have to cease operations by December 2019 due to declining levels in the Burrendong Dam. In May, dam levels were at 6.0%; by September levels had fallen to 4.6% capacity; by December capacity with increased evaporation, could decline below 3.0%.

Since July 2018, the River Murray system has remained in the driest 7% of records over the past 114 years. The Bureau of Meteorology has estimated that there is a 50% chance an El Niño will develop in 2019 and this estimate is double the normal likelihood at this time of year. The current weather system will be exacerbated by a sudden stratospheric warming event (see last page) moving from the Antarctic into southern Australia. According to the Bureau of Meteorology, the last event over southern Australia occurred in 2002 and caused increased warming during the summer months – again during a severe drought at that time.

The Last Drop

Cobar has no local effective water supply and relies on pipeline water from the Burrendong Dam, 390 km to the south-east. The dam is at 4.0% capacity and will be effectively empty by yearend. Water will have to be imported using NSW Railways. Since the system is radial on Sydney. the option for obtaining water from the southern supplies, except by road haulage, are restricted. Sydney’s principal water reserve, Warragamba Dam, is at less than 40% capacity and has extracted water from the Shoalhaven to top up its own supplies.

On ABC AM, 16th September, the Deputy Prime Minister spoke on water shortage in New South Wales. In particular, Dubbo (population 76,000 – 2016 Census) would be without water by yearend. Rationed at 100 L/p/d this equates to nearly 7 mega litres per day. The Deputy Prime Minister mentioned a National Water Grid Authority is to be created to attend to water security and distribution across eastern Australia. However, a lead time for results was not specified. A penultimate comment was “It must rain eventually”. It was a depressing interview. Concluding this penultimate paragraph is a further example of Government futility under crisis. Barnaby Joyce is appointed the sinecure of Drought Envoy by the Morrison Government. No report is required and nothing has materialised  except SMS messages to the PM, estimated cost to date $200,000 for this quango.

The Minister’s observation that Dubbo could be out of water by yearend reinforces the warning by Cobar Shire that mining operations may have to cease by the end of 2019. The Central West will still be hoping for spring rains between September and November but the BOM forecast is not encouraging. It is now probable, however, there will be water transfer from Windermere Dam (31% capacity, 20th September) to the Burrengdong Dam to supply emergency water to the Central West.

Sudden Stratospheric Warming  30 August 2019

(news.com.au)                                            

References.

Cobar Water Board, ——–, History NSW Government, 2000, Water Management Act 2000 NSW Department of Primary Industry, 2007,  Cobar’s Mining History Nyngan Observer, 2 June 2017, Albert Priest Channel Cobar Weekly, 21 June 2017, Cobar Water Health Standard Cobar Water Board, 2017-18, Annual Report Daily Liberal, 2 February 2018, Cobar Water Supply Utility Engineering, 11 May 2018, Infrastructure Upgrade Cobar Shire Council, ——– , Water Cobar Shire Council, April 2019,Water The Guardian, 24 May 2019, NSW Towns face Water Emergency Water NSW, 2 September 2019,Regional Water Availability The Guardian, 23 September 2019, Barnaby Joyce, Drought Envoy

John Hugh Hill

lurgashall@westnet.com.au

towardsthefinalhour.com   Current Affairs Flash Points