Transmission Company Victoria has begun environmental surveys on public and private land to help pin down the final route for the controversial transmission line from near Ararat to cross into NSW near Kerang.

Many land owners say they will continue to refuse access to their land in continued opposition to the plan.

TCV now says as part of the environmental assessment process, it will do aerial surveys this month "to capture high resolution elevation and geographic data to inform design routes refinement, cultural heritage management plans and environmental impact assessments".

The power company said a small fixed-wing plane will fly between 500 metres and 1km above the ground, along the route of the draft corridor.

Flights will take place over several days to mid-November.

TCV earlier this month narrowed down the proposed route from 50km wide to 2km wide.

About 540 properties have been identified in the draft corridor.

In the two months since TCV began contacting landholders to advise them their property or farm is currently within the new draft corridor, the company says it has so far successfully "made contact" with owners of over half those properties.

The company says it needs to capture light detection and ranging (LiDAR) data and aerial imagery from the air.

Governments have set a 2025 deadline for the selection of the final 70 metre-120 metre easement needed to locate the 500 kilovolt double-circuit overhead transmission line carried by towers about 80 metres high.

Opponents of the VNI West transmission line have started a campaign to "lock out" anyone asking to access their land.

The project, which continues to spark angry protests across regional Victoria, aims to connect the Victoria and NSW energy grids.

Opponents and representative groups like the Victorian Farmers' Federation have advised landholders TCV does not yet have a legal right to access farms.

TCV has offered to pay landholders $10,000 for access.

"Our land team will negotiate access agreements with landholders, including biosecurity requirements, before any field surveys commence," TCV says.

Attempts to access private land have met with continued resistance.

TCV says its survey teams will undertake ecological surveys on public land including roadside reserves, looking at remnant native vegetation and other areas of ecological interest.

"Data gathered from these surveys will add to TCV's understanding of the flora and fauna across the draft corridor and support the work underway to find the best location for the VNI West line with the least impact on farms, the environment and local communities," TCV said.

The power company said the small team of ecologists may be spotted by local community members as they drive on local roads, stopping frequently to assess, walk around and photograph the vegetation.

TCV needs to progress the studies as part of the environmental assessment required for the project under government regulation.

The company said it would be asking to access a small number of private properties during this phase of the study.

"The site investigations will continue for several months, requiring visits to multiple locations as specialists document vegetation classifications, assess their conditions, and explore the potential presence of specific flora and fauna.

The company says it wants to further refine the route for VNI West which "has the least impact" to agriculture, cultural heritage and values, rural communities and the environment".