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 is 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 Murray Dairy Murray Muster conference.
He told the conference there was a continued reduction in the number of dairy farms and a move away from summer irrigation by the dairy industry.
“You can see we have gone from high-reliability water shares of about 1600 Gl and dairy had a fair share of proportion of that.”
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.
Without having the advantage of a crystal ball, Mr McAllister said he expected water availability would continue to get tighter and exert more pressure on the dairy industry.
Despite the move towards larger farms, the survey has shown there is still a large number of small to medium enterprises in the Central Goulburn, Murray Valley, Rochester and Torrumbarry districts.
Satellite maps developed for the report showed a reduced footprint for dairy in northern Victoria.