Under a Clyde North structure plan released by the Growth Areas Authority, an arterial between Thompsons and Grices roads would cut a swathe through Oakwood Riding School's 40-hectare property.

The non-profit riding school, run by a volunteer committee, says it would have to buy in $25,000 worth of hay a year if its paddocks were lost to the road - a prospect it could ill afford.

Oakwood Riding School treasurer Michael Hocking says the school would be forced to move from its four-year-old headquarters.

He said if the riding school was sold, it could also be doubly stung by a $3.8 million bill under the State Government's proposed growth areas infrastructure contribution.

Although the GAIC tax would be charged on the buyer of the property, it would force down the property's sale price, Mr Hocking said.

"We've invested millions into the centre. To break even, we'd need to sell for $7.8 million, if you include the GAIC charge."

He said Oakwood hadn't been formally notified of the planned road, presumably because the riding school was just outside the structure plan boundaries. He found out about the plan from a resident.

Mr Hocking, an outspoken critic of the GAIC tax, did not believe there was a government vendetta against the riding school.

"You'd hate to think so. They wouldn't be persecuting me. They'd be persecuting everyone in Casey who wants to ride a horse."

Casey councillor Geoff Ablett said a GAA representative he spoke to recently "had no idea" that the school's ability to grow hay and its suitability for agistment would be greatly compromised. He said he was awaiting a response.

"Locally, we should support the riding school staying out of the [urban growth boundary] and not being subjected to a road so they can continue to do what they do well."

At last week's council meeting, Cr Ablett successfully moved for Casey to ask the ministers for planning and racing to ensure equestrian trails and agistment areas were included in proposed subdivisions.

Public submissions for the plan close on February 18.