IT seems no amount of engineering will fill Lake Wendouree - not this summer anyway.In a report to be tabled at tomorrow night's council meeting the City of Ballarat sustainability director Ian Rossiter said the lake was 15cm below its expected level and unless above average rainfall was received over the next three months the lake would once again dry up over summer.Mr Rossiter's update on the $7 million lake water supply project provides councillors with the status of water harvesting options for the lake.He said the Brown Hill storm water diversion was the next supplementary water source to come on line and it would deliver 50 to 75 megalitres.Councillors have also been advised the weekly 14 megalitres of treated waste water to be delivered by Central Highlands Water "will be less than the evaporative losses during peak summer autumn hot windy conditions".Delivery of this water will start in December.The council has also presented Regional Development Victoria with a proposal from Ballarat Goldfields to supply more than 500 megalitres a year from the mine.Council would need to find money to share the cost of building infrastructure to deliver this water from the mine to the lake.The council has based its projections for the lake filling on annual rainfall figures from 2000-2007, all of which were below the long-term average.Despite this, Mr Rossiter said this year's rainfall to the end of September was 335.4mm compared with the average for that time span over the past eight years of 400.1 mm."The Lake Wendouree Water Supply Project is reliant on rainfall as being its major water input," he said. "The risk of further decreases in annual rainfall and increased evaporation must be considered in the long term and strategies (put in place) to augment the project with additional water supplies."