Plans to take water from Tekapo for irrigation are still "on the table", but the Opuha Water company acknowledges there are several hurdles to overcome.

The company outlined a $185 million proposal to take water from Lake Tekapo and irrigate 25,000 hectares, to the Canterbury water management strategy's Upper Waitaki committee in June, but a discussion document presented to the committee in Twizel on Friday suggested there were a "number of red flags".

Among the biggest concerns were the effects on environmental values and possible rise in generation costs, as Tekapo is one of the country's most important hydro lakes.

Upper Waitaki deputy chairman Simon Cameron said it was up to the company to decide whether the costs were worth it.

"Really, it's out of our hands; it's up to them to come up with something that passes all the hurdles," he said.

"There are a whole lot of issues to be considered, such as whether the cost of the proposal would balance against the importance of generation for the rest of the country, while the local runanga would obviously be concerned about any mixing of water."

Opuha Water chief executive Tony McCormick said the group was somewhat surprised by the tone of the discussion document.

"It didn't seem totally balanced, but in fairness it was looking at it from an Upper Waitaki perspective," he said.

"While Tekapo isn't our only option, we're not taking it off the table. In the grand context of the entire hydro system, the proposal does not involve taking a seriously significant amount of water. But there is a lot of planning still to be done."

Mr McCormick said other options included one which involved the Rangitata, but much of the discussion was still at a high level.

Upper Waitaki zone facilitator Nic Newman, who prepared the discussion document, said the committee would draw up a submission on the proposal at a later date.

Opuha Water co-director Dermott O'Sullivan - who is also the chairman of the Orari-Opihi-Pareora water management zone committee - spoke at the Twizel meeting on behalf of the company.

Mr O'Sullivan said later that he was "pretty happy" with the meeting and the Upper Waitaki Committee's decision to "leave the door open" for future access to water. "Tekapo is our fallback position, if you like, while we explore other options," he said. "There's a lot of work going on in that regard."

Mr O'Sullivan declined to elaborate further, citing privacy concerns.

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