Water Management Plan for the Town of Perenjori

The Rural Towns – Liquid Assets (RT–LA) project was established with the aim of integrating salinity, waterlogging and flooding control with development of new water supplies in wheatbelt towns, and where possible, finding ways of putting the excess water to commercial use. Following the identification of effective integrated water management strategies, these have been applied to the 15 Shires participating in the DAFWA led RT–LA project. This report summarises the outcomes from all scientific investigations undertaken for Perenjori. In addition it presents the water management options, a preliminary analysis of those options and the priority recommended ones. Due to the decline in rainfall over the past 10 years, Perenjori groundwater levels have shown a declining trend below the townsite since 2000, when groundwater monitoring by DAFWA in the townsite commenced. Hydrogeological studies identified groundwater pumping was not an effective solution for Perenjori to control watertable levels in the high salinity risk areas of the townsite. The studies demonstrated that only limited volumes of groundwater could be abstracted by pumping because the drawdown affects would be constrained by the geological properties. It is concluded that salinity control or water production from under the townsite via groundwater pumping is not a technically viable option. Instead, the RT–LA project has focused on surface water management options that will enable new water supplies to be developed which will also alleviate salinity, watertable, waterlogging and flooding problems. An integrated scheme such as this will provide cost effective solutions to the annual problem of irrigation water shortages. Over time, the proposed surface water diversion and harvesting schemes will reduce salinity risk by diverting and utilising runoff water which would otherwise have contributed to local recharge. Option 1, construction of a new 30ML dam in the paddock east of town belonging to Mr Jim Gilmour, is recommended as the first priority action. Along with the other options outlined in this Water Management Plan, Option 1 offers a combination of surface water engineering solutions to capture the town’s runoff and provide up to an additional 31 ML/yr, or 155 per cent of the total existing demand