Between 2015-16 and 2019-20, the survey found the number of farmers who own properties had decreased from 96 per cent to 83 per cent.
The land and water analysis of the GMID also found a sharp decline in dairy farms and water holdings since the year 2000.
In only four years between 2016 and 2020, the area occupied by dairy farms in the GMID had declined by about 30 per cent.
In the same period non-dairy grazing land had increased by about 40 per cent and cropping increased by 39 per cent.
The assessment, carried out by Agriculture Victoria, shows water use by dairy farms has declined from about 1065 Gl in 2001-02, to 585 Gl in 2017-18.
Dairy remains the single biggest consumer of irrigation water in the GMID.
AgVic researcher Andy McAllister presented the findings of his report into landscape changes at the recent Murray Dairy Murray Muster conference.
The survey also found a move away from summer irrigation.
When water prices increased beyond about $150/Ml to $200/Ml, irrigators no longer participated in the temporary market. Farmers buying above this level were often applying the water selectively.
There was an increased reliance on allocation trade generally in the GMID, with an increased gap in high-reliability water ownership in pre- and post-drought years.
The changes, Mr McAllister said, were driven by restructuring and how dairy farmers manage water allocation and trade.