The Scottish government is set to give permission for a controversial holiday park development at Loch Lomond, overturning the decision of the national park authority.

Theme park operator Flamingo Land wants to build a £40m resort called Lomond Banks, featuring a waterpark, monorail, hotel and restaurants.

The proposal sparked protests and was initially rejected in September by Loch Lomond and the Trossachs National Park authority, who said it did not comply with environmental and nature conservation policies.

But that was appealed to the Scottish government reporter, who has now said they intend to grant permission – subject to a legal agreement between Flamingo Land and the park.

Development director for Lomond Banks Jim Paterson said it was a “real milestone moment” which had been “a long time in the making”.

But Scottish Green MSP Ross Greer, who was a long-standing critic of the plan, said the development would cause “irreversible damage” and the decision was an “anti-democratic outrage”.

He added: “Their destructive plans were unanimously rejected by the National Park’s board, opposed by the Scottish Environment Protection Agency, the National Trust for Scotland, the Woodland Trust, the Park’s expert planning officers and 155,000 people who joined our Save Loch Lomond campaign.

“This greedy developer would not take no for an answer and I am shocked that government officials have put Flamingo Land’s interests above the need to protect Loch Lomond.

“We are urgently considering our options for continuing this fight. I will leave no stone unturned in the campaign to save Loch Lomond.”

In an 80-page notice of intention, the planning reporter said there had been a “very significant” number of objections to the proposal, with many claiming the site was unsuitable.

But he said it did not conflict with the local development plan for the area, or the rules set out in the government’s national planning framework.

He said the site could operate safely despite being within a flood risk area, and also said there could be “locally significant” benefits in terms of jobs and a boost to the economy.

However, the reporter said full permission would only be granted if an agreement could be reached between the developer and the park on the “Lomond Promise”.

This is a pledge by Flamingo Land to promote local businesses, provide jobs for local people and suppliers, and develop plans to protect the environment and prevent anti-social behaviour.

There are 26 weeks for this agreement to be reached – and if it is not, the reporter will reconsider whether to approve or reject the application.

Flamingo Land first submitted plans for the site in 2018, but withdrew them the following year after a wave of negative reaction.

It submitted updated plans in 2020, insisting the proposal would be a “major step away” from its other resorts, including a theme park and zoo in Yorkshire.

But the Loch Lomond park authority board ruled that the updated scheme still conflicted with both regional and national environmental policies.

Stuart Pearce, “director of place” for the park authority, previously said the plans created “unacceptable risk” of flooding of the River Leven.

More than 174,000 people signing a petition against the project.

And at a public meeting last year, the Balloch and Haldane Community Council said it would “go against the very will of the people who live in the area”.

Mr Paterson, from Lomond Banks, said he was “delighted” with the decision from the Scottish government reporter.

“Our proposals have been informed by more than two years of positive engagement with the local community and key stakeholders,” he said.

“At the heart of our plans is a commitment to sustainable investment, local jobs, and a long-term partnership with the area, backed by our legally-binding Lomond Promise to ensure the future prosperity of Balloch and beyond.

“As we look beyond today’s decision, we remain committed to being a strong and valued contributor to the local economy and we look forward to progressing with our proposals as we now consider detailed planning.”

The Flamingo Land resort in North Yorkshire has been operating since 1959, initially as a zoo

The name comes from a colony of the brightly coloured birds that were among the first animals on the site at Kirby Misperton.

By the 1970s, the zoo was losing money, and the attraction was revamped as a “day out” experience with a growing focus on amusement rides.

The Yorkshire site continues to have exotic animals, and there is also a large holiday village with static caravans and lodges.