In a statement to the media, Goulburn-Murray Water says that the purchase is about 3000 megalitres more than the minimum required to maintain system reliability and avoids the need for further infrastructure.

This thereby helps to contain future operations and maintenance costs for irrigators, the company said.

G-MW says the additional water savings generated by this purchase will improve the environmental health of the Broken, Goulburn, Snowy and Murray rivers, as well as the reliability of supply for customers.

Purchases will be progressed with 54 irrigators who expressed interest and are located in the targeted areas of the Broken Creek and Majors Creek sections of the system, and on the Broken River below Gowangardie weir.

Purchases from these areas will maximise the benefits for remaining irrigators by reducing losses and improving service delivery.

Letters are also being sent to 22 customers who expressed interest in selling, but whose offers will not be taken up.

G-MW managing director David Stewart said he understood the disappointment that some customers may feel, but the response from the areas offering greatest system benefits was so strong that further purchases were not required.

"Purchasing this level of entitlement has the additional benefit of reducing the size of the planned Rain Rejection Storage on the Mokoan Inlet Channel," Mr Stewart said.

"This will allow Holland's weir to be decommissioned, which avoids the need to construct a fish passage."

The impact of this level of purchase on the remaining irrigators was a key consideration when determining the extent of the purchase.

The decision has been supported by the Victorian Farmers Federation.

"This is a good and equitable outcome for each party involved in the decommissioning of Lake Mokoan," said Richard Anderson, VFF Water Council chairman.

Once Water For Rivers has completed its agreements with customers, G-MW will commence the final works for the Return to Wetlands project.