Water and Waste Committee 21 October 2009
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1 WATER AND WASTE COMMITTEE 1 21 OCTOBER 2009 WATER SUPPLY AND DEMAND, PORT DOUGLAS/MOSSMAN WATER SUPPLY SCHEME Eric Zesers : 24/22/212-03: #2339446 RECOMMENDATION: That Council notes the report. INTRODUCTION: The water supply for Mossman, Port Douglas, Craiglie, Mowbray, Newell Beach, Cooya Beach and Cassowary is sourced directly from Rex Creek which is a tributary of the Mossman River. Due to unprecedented dry conditions, water levels in Rex Creek have fallen to levels that have required the following actions be undertaken: • Implementation of Level 1 Water restrictions for Port Douglas, Mossman, Craiglie, Mowbray, Newell Beach, Cooya Beach and Cassowary, on 2 October 2009. • Progression to Level 2 Water Restrictions on 12 October 2009. • Application to the Department of Environment and Resource Management (DERM) for a temporary emergency extraction permit for water from the Mossman River. • Application to DERM for an internal review of the original decision relating to the licence limit to extract water from Rex Creek to supply water to Port Douglas and Mossman. • Application to DERM to exceed license limits for water extraction during periods of low flow. This report provides details of the above matters. BACKGROUND: The winter of 2009 has seen the lowest winter rainfall on record at the Low Isles Light House – 25.7 mm (average is 136.4 mm) and at the Cairns Airport – 17.2 mm (average is 102mm). As a result of the unprecedented dry conditions, run of river water supplies such as Rex Creek can also be expected to reach record lows or potentially could dry up completely. This has necessitated the introduction of water restrictions and plans to implement emergency water supplies as a contingency if consumption cannot be reduced to sustainable levels and/or it is not possible to extract sufficient water from the existing intake on Rex Creek. Agenda – Water & Waste Committee 21/10/09 - #2330550 2 Water Demand Permanent Water Conservation Measures have been in place in Division 10 since May 2008. However, water demand has increased steadily since February 2009 primarily due to the extended dry period. Cairns Regional Council 2009 Water Production Port Douglas, Mossman & Whyanbeel 500.00 450.00 400.00 350.00 300.00 Port Douglas / Mossman 250.00 Whyanbeel 200.00 Total Production Production in ML in Production 150.00 100.00 50.00 0.00 l r i e y e uary ary pr Jul b n u A May Jun m br March August ctober Ja e te O cember F ep e S NovemberD Months Daily water production since 1 September has exceeded 16 ML/day at an extraction rate of 185 litres per second. Daily per person consumption has been up to an estimated 1500 – 1600 litres per person per day, based on a serviced population of 10,000 people. Daily extractions based on water treatment plant production figures are shown in the following graph Agenda – Water & Waste Committee 21/10/09 - #2330550 18 Mossman Treatment Plant - Daily plant production 16 16.8 14 12 3 10 ML/day 15.0 16.3 Mossman Treatment Plant Production 11.9 8 15.2 6 14.1 4 Stage 2 restrictions target 14.4 15.3 2 0 Stage 1 restrictions 13.7 15.0 16.1 introduced 21/09/2009 Rex Creek Flows 22/09/2009 14.5 14.5 23/09/2009 During extended dry periods water flows in Rex insufficient water flowing into 24the/09/ 20in09 Management Plan states that the 25/09/2009 12.1 requires sandbagging to direct flows into the26/09/2009 intake. Sand bags have been in place 13.2 since September 10 2009. It 13.9 27/09/2009 Pressure to Mossman allowed to pass beyond the water intake at this flow level. reduced by 10%. Flow 13.9 28/09/2009 to parts of Port 14.4 Douglas reduced 5%. Flow volumes are estimated from taking a 29/09/2009 14.6 a formulae to calculate discharge levels. The 30/09/2009 last 12 months is shown on the following graph. 1/10/2009 to this. The second graph shows the water 12.3 illustrates the decline in water level during that period. 2/10/2009 12.1 3/10/2009 Stage 2 restrictions It should be noted that the flow is an esti 4/10/2009 13.2 introduced 11.5 influenced by two factors. Firstly, the formu 5/10/2009 12.8 actual flow readings taken at different trigger for level 1 water restrictions is when Rex Creek 6/10/2009 formulae is dependent on a range of factors and not be 100% accurate.should be noted that environmental flows have been take to meet demands. Councils7/10/2009 Drought Secondly, when the creek is 8/10/2009 Creek can fall to levels whereby there is pool at the intake to ensur 9/10/2009 therefore not accurately reflected by the water depth when sandbagging occurs. 10/10/2009 11/10/2009 12/10/2009 water depth reading and extrapolating using 13/10/2009 recorded water level in Rex Creek for the 14/10/2009 level Datain Rex does Creek not existsince for May the 2009 period and prior sandbagged, the actual water level is made deeper in the e that enough flow enters the intake. The flow volume is water depths.mate The only degree and theof accuracy level of foraccuracy this is lae used to calculate the flow is based on Agenda – Water & Waste Committee 21/10/09 - #2330550 per second. flow depthtobetaken. Atthat On Tuesday13October thesandbagswerere REcorded Water Level Height (m) Recorded Water Level Height (m) 0.000 0.500 1.000 1.500 2.000 2.500 0.000 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800 0.900 1.000 1/05/2009 30/10/2008 13/11/2008 8/05/2009 27/11/2008 Agenda –Water&Waste Committee 21/10/09 -#2330550 15/05/2009 11/12/2008 Flow levelsinRexCreekatthewaterintake 22/05/2009 25/12/2008 Rex Creek Stream Gauging - May to October to May - Gauging Stream Rex Creek 8/01/2009 29/05/2009 22/01/2009 timetheflowlevelwas estimatedtobebelow200litres 5/06/2009 5/02/2009 RexGauging Creek Stream 12/06/2009 19/02/2009 19/06/2009 5/03/2009 19/03/2009 26/06/2009 2/04/2009 4 Height (m)Height 3/07/2009 Date 16/04/2009 moved toallowanaccurate readingof 10/07/2009 Sandbagging commenced 24/7/09 30/04/2009 17/07/2009 14/05/2009 28/05/2009 24/07/2009 11/06/2009 31/07/2009 25/06/2009 7/08/2009 9/07/2009 23/07/2009 14/08/2009 6/08/2009 21/08/2009 20/08/2009 28/08/2009 3/09/2009 4/09/2009 17/09/2009 1/10/2009 11/09/2009 5 Of concern is the timing of when flow levels increased in 2008. That did not occur until mid December following an estimated 138mm of rainfall over the winter period. If the same pattern occurs this year the concern is that Rex Creek will be close to drying up based on current trends. Water Extraction Licence The former Douglas Shire Council had an Order in Council to extract 513 ML/year from Rex Creek for water supply. The current annual extraction rate is approximately 3,700 ML/year. An application was made to DERM on September 25 2008 to increase the extraction limit to reflect current and future demand for water. The application sought to increase the volume of water taken to 5,200 ML per annum at an extraction rate of 200 litres per second. An information notice for the licence application was received from DERM on August 20 2009. The notice advised an approved extraction of 4,800 ML per annum at a maximum rate of 170 litres per second. With a reducing sliding scale as the flow in the creek falls below 300 litres per second as shown in the following table. Water extraction schedule from Rex Creek water license Scheduled for Extraction - Rex Creek Maximum Extraction Flow Rex Creek Flow Rate Rate Litres per second Litres per second <40 0 41-60 20 61-80 30 81-100 40 101-120 50 121-140 60 141-160 70 161-200 80 201-250 120 251-300 150 >300 170 Water Restrictions Level 1 water restrictions were introduced in the affected areas from Friday October 2. Restrictions are introduced in line with the Cairns Regional Council Drought Management Plan and the Water Restrictions Policy (No1:01:02). The Drought Management Plan restriction triggers are directly taken from the Douglas Shire Council approved Drought Management Plan. Agenda – Water & Waste Committee 21/10/09 - #2330550 6 The following communication measures have been undertaken - • A half page advertisement detailing the water restrictions and reasons for implementation was placed in the Port Douglas Mossman Gazette on October 2, October 8. • Local media taken on a site visit to the Rex Creek Intake to view low water levels. • Media releases issued on September 29 and October 7. • Community Service announcement issued to media on October 1. • Information of restrictions placed on Council website. • Variable message board placed in prominent locations on the Cook Highway at Craiglie and Port Douglas informing the restrictions are in force. • Communication sent to industry associations to distribute to members to notify business responsibility to reduce water. (Port Douglas Chamber of Commerce, Port Douglas Daintree Tourism) • Contact made with major commercial water users • Inspections by Water & Waste staff. Council has reduced watering of Council land (e.g.