Supplying over 5000 people with water when the dam runs dry - the Stanthorpe water supply story Seren McKenzie Southern Downs Regional Council Abstract: Stanthorpe is a town in southern Queensland in the local government area of Southern Downs Regional Council. Stanthorpe has a stand alone water supply (ie, no connectivity to any water grids) and the over 5000 residents are supplied by Storm King Dam. The capacity of Storm King Dam is just over 2000 ML and the Dam has never run dry in over 60 years, albeit it has come close. Stanthorpe itself does not have a high population growth however is a tourist town and does accommodate a high transient population due to the nature of the horticulture and agriculture businesses in the region. Following years of low to zero rainfall and intense drought coupled with another failed wet season in 2018/19, it became clear to Council that Storm King Dam was going to run dry before the next wet season and actions needed to be taken to ensure ongoing water supply for Stanthorpe. It was too late to plan and build a pipeline from Warwick, some 60 kms away, and Council was not financially resourced for such a project. Working closely with the State Government and consultants and contractors, Council was able to deliver a solution by trucking water from Warwick to new water tanks at Storm King Dam. The total project value is valued at around $15 million with $2.6 million in capital works and the remainder in the carting of the water through to February 2021 (if required). This project is an example of a collaborative solution for a large community, as well as the amazing things we can achieve in a short amount of time when we set our minds to it. Keywords: Drought, Stanthorpe, Water Carting, Collaboration Water Management The Southern Downs Region, like many parts of Queensland, has been in drought for a number of years. Water restrictions were applied from 2018; • June 2018 - Medium (200 l/p/d) • November 2018 - High (170 l/p/d) • March 2019 - Extreme (120 l/p/d) • September 2019 - Critical (100 l/p/d) • December 2019 – Emergency (80 l/p/d) Council also engaged contractors to undertake leak detection works and were able to identify a number of leaks in the network that did provide some minor savings of water. Water education and water initiatives were important and had a large impact; • shower head exchanges • water tank rebates • shower timers and bathroom stickers • education campaigns through schools and online resources • media and regular community updates o weekly video update on council’s facebook page from the Mayor o monthly water contingency plans presented at council meetings o face to face community Q and A sessions every few months, where water was a hot topic. • Developing Water Efficiency Management Plans with businesses with high water use. • Information packs and resources for all businesses. Whilst consumption dropped significantly (figure 1) and the Dam was used for as long as possible, it was clear to council that action needed to be taken to ensure Stanthorpe maintained a supply of water. Stanthorpe WTP Monthly Water Production 13 months to Jan 2020 80 70 60 Consumption 50 Winter 5 years 40 Summer 5 Monthly consumption ML consumptionMonthly 30 Years Annual Average 20 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan 2018 2019 2019 2019 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020 Figure 1: Water consumption for Stanthorpe over time Community wellbeing During the drought, along with businesses being asked to use less water and residents being restricted in their daily use, community morale has been greatly impacted. The region has been given a high profile in the media with ‘day zero’ messaging (which council worked hard to negate) and constant images and stories about the Dam running dry and the town of Stanthorpe having no water. The economy suffered with crops not being planted resulting in fewer backpackers, fruit trees reportedly being removed due to them dying, and the tourism sector being impacted as people ‘didn’t want to use the water here’. The incredible spirit of Australians and helping out a mate has been evident throughout this experience. The amount of water being donated - from truckloads down to small bottled water, was such that two large charity organisations were formed in Stanthorpe to receive and distribute the water. At times there were up to 20 truckloads of pallets of water being delivered through the fundraising efforts of various organisations. There is no doubting the relief this brought to both rural residents having to purchase water due to their tanks being empty, and to the amount of water being taken from the council standpipes – at times up to 20% of the monthly water used in the town. Through the community drought funding program, council was able to use some of the funds for residents to pay for carted water – over 300 truck loads of water were distributed across the region under this program. Council also made free showers available to rural residents at the fitness centre in Stanthorpe. At the peak of the drought, just days after council had moved to Critical water restrictions, the communities’ resilience was again tested with the Applethorpe and Stanthorpe fires. These fires started in Applethorpe to the north of Stanthorpe, before moving south to Stanthorpe where the fire jumped the highway and threatened the town. Council worked closely with emergency services and most of the water used to fight the fires was not taken from the town water supply, resulting in little impact on the already low level of water in Storm King Dam. Stanthorpe was now in the media about not only drought and running out of water, but also for the fires. The impact was felt again with visitors now staying away due to fires and lack of water. However once again, donations for the town flooded in and the region felt the compassion of others. Determining the options for water supply Although council had a number of options discussed at a strategic level, and some detailed work being undertaken by consulting engineers, there was no definite answer to how to supply the water after the 2018/19 wet season failed to deliver rainfall. Council had previously submitted an unsuccessful funding application to build a pipeline some 65 kms between council’s other dam near Warwick, Connolly Dam, which would provide connectivity between the three main dams in the region (including Leslie Dam at Warwick which has a much larger storage capacity). As part of the process to determine the best option to provide water to Stanthorpe, council realised we needed to better understand Storm King Dam and how it ‘behaved’. A bathymetric survey was undertaken which determined there was approximately 115 ML equivalent of silt in the Dam, resulting in an updated storage curve and more accurate ‘run out’ dates. Department of Natural Resources Mines and Energy (DNRME) have been close partners in this process and were able to run historical modelling for the Dam, as well as produce a run out model based on historic evaporation and seepage, climatic conditions and expected volumetric use over different scenarios. Early on, there was some thought based on the historic modelling that the dam would not run out and there was no need to move through to contingency planning, however council was not prepared to take that risk and engaged GHD consulting engineers to assist with validation of options for council to consider as well as a business case for funding of the preferred option. GHD undertook a number of modelling cases, including storage predictions based on best case (dam filling up overnight – which it has in the past) through to no inflow which resulted in the dam reaching minimum operating level of 200 ML in January 2020. This work was being undertaken in July 2019, meaning in the worst case scenario there was only a maximum of 6 months to construct suitable infrastructure for water to be transported to Stanthorpe. Whilst GHD were working through the options report council officers were actively determining the viability of options such as rail transportation of the water. It was established quite early in the process that although a rail line exists between Stanthorpe and Warwick, a number of logistical issues would accompany this option, with the major issue of the lack of available rolling stock for the water transportation being enough to rule out this option (along with issues such as having to pump the water uphill from unloading or truck it to the WTP, nowhere for the trains to ‘turn around’ etc). The preferred option identified was transporting raw water from Connolly Dam, by trucks, to storage tanks and then into the raw water line through to the treatment plant (figure 4). The additional benefit of this solution is that should Connolly Dam run out of water, Leslie Dam can also be used by reversing the raw water line. Whilst this was the most logical and economical way to get water to Stanthorpe, there were a number of elements to this project to be quickly determined. Although it was known we had, on paper, until December 2019/January 2020 for water supply in the Dam, the unknown was the water quality and how quickly it would deteriorate and remain at a treatable level as the Dam level dropped. Figure 4: Preferred option for water supply to Stanthorpe (GHD options report, 2019). Following council agreement to progress with this option, GHD were engaged to develop it into a Drought Assistance Funding submission to the State government to assist in both the capital works elements of the project and the water carting.