Hydraulic testing of a scale model has shown the effectiveness of gates to be added to the Ross River Dam spillway as part of a $60 million-plus upgrade.

NQ Water Manager Engineering Rob Saunders said the tests had proven the gates would fulfil their key purpose in effectively managing water levels and flow.

Three radial gates will span the 40-metre spillway. Each will act independently and the design incorporates computerised and manual operational modes for flexibility and safety.

The gates were recommended by a panel of internationally recognised experts in dam construction and safety.

They recently visited the Brisbane laboratory where the hydraulic model of the spillway and gates was put through its paces.

"The model was built and operated in a specialised test laboratory," Mr Saunders said. "This type of testing is standard procedure in projects of this kind and the panel was extremely happy with the outcomes."

The gates will be fitted to the crest of the dam spillway, which was lowered by 3.6m late in 2003 as part of the first stage of the upgrade. They are expected to be operational by October 2006.

The entire project will take until mid 2008 to complete and also involves upgrading sand filters and rock work along the 7.5km length of dam embankment.