Gnangara Metering Project
The Gnangara Metering Project was a funded by the state government through the former Department of Water, to install water meters on licensed groundwater bores on the Gnangara Groundwater System. The project came about in response to recommendations from the Irrigation Review Steering Committee in 2004 that more comprehensive metering be introduced on the groundwater system. The steering committee advised that in order to improve management of the groundwater resources, which were under significant stress due to declining water levels, it was necessary to obtain better data on private water use.
In direct response to the steering committee’s recommendation, the state government allocated funds to the department to support a three-year metering pilot program across the groundwater system, which commenced in late 2004. The funding was to facilitate the supply, installation, maintenance and monitoring of state-owned water meters on non-urban licensed bores. Meters were installed on licensed bores drawing between 5000 and 500 000 kilolitres per annum from the groundwater system. Upon completion of the pilot project in 2007/08, new funding was provided to the department to continue the expansion of state-owned metering across the groundwater system. Meter installations were completed in 2010 for approximately 900 licensees.
1269 state-owned water meters were installed in 20 groundwater subareas in Gnangara. The subareas targeted for metering varied from fully allocated horticultural and viticultural precincts (e.g. Carabooda and South Swan respectively) to areas comprising primarily of semi-rural, lifestyle properties with limited commercial irrigation activities (e.g. Adams). Initially meter readings were collected monthly by the department and then less frequently once enough data was gathered. Currently readings are recorded once annually by the department for the majority of meters.
The water use data collected from the state-owned meters benefited both the department and licence holders. Licensees who were initially unsure about the project found that by metering their bores they could obtain useful information to help their business operations. Licence holders who had multiple bores were able to compare data between bores and determine if any bore was pumping inefficiently. They could also use the data to analyse their irrigation practices and make changes to improve their water use efficiency. As an additional benefit, some licensees with meters were able to more precisely regulate their fertilizer application, through ‘fertigation’, thereby improving root growth and plant health, and also reducing their fertilizer usage. These savings in fertilizer and water ultimately meant cost savings to licensees and benefits to their business.
The water use data collected enabled the department to work with licensees to help them comply with their licence conditions.
Data from the state-owned meters was also used by the department to undertake a number of specialised water resource management and planning activities. For example, the accuracy of the computer model of the Gnangara Groundwater System (PRAMS) was improved, enabling better forecasting of future groundwater trends. Having more precise water use information allowed us to prepare pilot water accounts to help inform the development of the National Water Accounting Standards. Experience with the Gnangara Metering Project also allowed the department to make a significant contribution to the National Framework for Non-Urban Water Metering.