Dam operator Seqwater will increase releases from south-east Queensland catchments in preparation for heavy rain in the region.
The Weather Bureau says showers will develop into rain tonight from Townsville south to about Gladstone.
Wivenhoe Dam, west of Brisbane is 90 per cent full and dam operators will almost double the release rate to 280 cubic metres per second.
That is expected to bring the dam back to the temporary full supply level of 88 per cent.
Downstream, Colleges Crossing will be closed tonight and is likely to remain shut until the rain system clears the dam catchments.
Seqwater spokesman Mike Foster says there will also be releases from North Pine Dam to the north-east.
"The minister has taken the decision to reinvoke the temporary full supply level for North Pine Dam and that will bring it back to 88 per cent," he said.
"We'll start operationalising that decision this evening."
The Weather Bureau has downgraded its forecast from 300 millimetres to 200 millimetres of rain in state's south-east.
It predicts showers will develop into rain tonight from Townsville to Gladstone.
Senior forecaster, Pradeep Singh, says the system will move south tomorrow affecting coastal communities to the New South Wales border.
"Generally around that area - 200 to 250 - localised falls but there could be widespread falls in excess of 100 millimetres along the coastal areas during the next two to three days," he said.
"Then the showers are set to continue for the rest of the week along coastal areas.
"Over the duration of the next three days it'll affect most of the coastal areas generally in areas south of about the Lower Burdekin area and extending up to 50 kilometres inland.
"Showers and storms in the rest of eastern Queensland."
In the past 24 hours areas near Mackay have recorded 69 millimetres of rain, while 63 millimetres was recorded at Springsure and 50 at Emerald.
© ABC 2013
17:37 EDT Much of western New South Wales has begun a heat wave, reaching at least five degrees above average for at least five days, averaging a maximum of 35 degrees or more.