Following recent rain, outflow from Lake Kepwari has begun providing river flow for the first time this year to the downstream of the Collie River South Branch and its pools.
Until recently, rainfall recorded in Collie since the start of the year has been approximately 350mm. This is the lowest recorded annual rainfall since 2010. The duration and intensity of rainfall experienced to date has resulted in extremely low flows in the upstream reach of the river, which, in turn, has caused outflow from Lake Kepwari to occur later in the year than anticipated.
Rehabilitation works on Lake Kepwari, which was once an open cut coal mine, started in the 1980’s alongside mining operations and continued after mining ceased in 1997. The originally approved plan for Lake Kepwari was a closed catchment design resulting in significant deterioration of water quality within the Lake. However, after extensive research and investigation, including a trial of through-flow between 2012-2016, Premier Coal modified the plan to permanently divert the Collie River back to its original path through the mine void. This revised plan for permanent flow-through was presented to the Shire of Collie and its Weeds and Waterways Committee, and finally approved by the Premier Mark McGowan, Minister for State Development, Jobs & Trade in November 2018.
Premier Coal continues to work with State Government to facilitate a handover of Lake Kepwari to enable the government to open the lake for public use.
Jim Falconer, Operations Manager at Premier Coal, commented, “Despite an unusually dry year, now with appropriate rainfall it is absolutely terrific to see Lake Kepwari performing as it was designed to do and contributing to the downstream health of the Collie River. We look forward to the future enjoyment of the lake by residents of Collie and visitors alike.”
The outflow from the Lake Kepwari depends on rainfall in the upstream catchment, the reduced rainfall this winter is what has caused the outflow of Lake Kepwari to occur later than expected. The ‘flow through’ of the Collie River South Branch through Lake Kepwari improves the water quality in Lake Kepwari, particularly in terms of elevating pH, increasing nutrients and reducing metal concentrations. The Lake also helps to improve water quality in the Collie River South Branch by reducing the nutrient load in the river.