A businessman says 6,000 leaflets sent out to homes near Bontnewydd in Gwynedd contain misleading information about a new bypass route.
Gypsy Wood outdoor attraction owner John Evans said the pamphlet states one road passes 'near' the park.
But when he checked he said he was devastated to discover it would be going right through the "nature area".
A Welsh Assembly Government spokesman said every effort would be made to rectify any inaccuracies.
"Basically the leaflets show that one of the proposed route would be going 'near to Gypsy Wood park', whilst it goes through it," he said.
"We were devastated to find that it would in fact go through our nature area, because that is the whole basis of the park to get children involved in nature," he added.
Mr Evans said even at the public consultation meetings it was unclear if his land would be affected, and it was not until they got a "blown-up version" of the map that the true effect became apparent.
"It is misleading because people will think 'that route does not affect anyone', when they see the plan," he said.
The businessman said he realised that someone would be affected whatever route is finally chosen but by making the leaflets unclear it was taking the "democratic right" away.
Public opinion could swing towards one route over another because of misinformation, he said.
A Welsh Assembly Government spokesperson said consultations were important to "engage local residents and businesses into plans which may affect them".
"If inaccuracies are identified in any of the materials we produce we will of course make every effort to rectify them so as to keep the public fully informed throughout the process."