QUEENSLAND dams are being pushed far beyond their limits as Cyclone Debbie's flooding rains pour in, forcing dam managers to consider when and how to release water.

Outside of Mackay, Sunwater's Kinchant Dam went from 98% full to now topping 115% full in a little over 24 hours as Tropical Cyclone Debbie prepared to make landfall.

It is now holding 10,000ML -- or 10,000 million litres -- beyond its marked capacity.


The smaller Mirani Weir - fed by Mackay's Pioneer River - has exploded from 119% capacity where it had just 500ML above its maximum, to now being at 386% capacity. At full, the weir is designed to hold 2800ML

It was holding more than 10,000ML of water as of 8am on Wednesday.

To the north, Peter Faust Dam had more than 11,000ML flow into the dam in one day, pushing it to 306,000ML or about 62% capacity.

Wappa Dam spilling after rain.
Wappa Dam spilling after rain. Contributed

Gladstone's Awoonga Dam is at 85% capacity with up to 70mm forecast.

In the south-east, Wappa Dam on the Sunshine Coast is already overflowing and spilling over the dam wall. And that's as the Bureau of Meteorolgy predicts that 90mm - 200mm could fall in the area tomorrow.

Somerset Dam near Kilcoy will release water today that will be captured by Wivenhoe Dam downstream as water managers SEQWater attempt to balance the volume of the two dams. 

Somerset is about three-quarters full (74.5%) while Wivenhoe Dam remains at 67.9%.

A spokesman for SEQWater said there would be no releases of water from Wivenhoe Dam that would impact further downstream.

Both Sunwater and SEQWater have been approached for further comment.