A class action stemming from the Brisbane floods of January 2011 has moved a step closer, with law firm Maurice Blackburn releasing maps of areas it says were hit following negligent operation of the Wivenhoe and Somerset dams.

It says the areas along the Brisbane River would either have avoided flooding or suffered less if the dams had been operated properly.

In total, about 29,000 homes and businesses were flooded in the catastrophe, but Maurice Blackburn cannot yet say how many may be eligible for compensation if the action succeeds.

The case is expected to be lodged with the courts in April, aided by litigation funder IMF. Its target will be the Queensland Government and its Seqwater authority.