The federal government has received not a drop of water for the $80m it spent on buying water entitlements from Eastern Australia Agriculture in 2017, a company once linked to the energy minister, Angus Taylor.

Taylor was a director and co-founder of EAA, an agribusiness in Queensland, which was backed by a group of foreign investors. Taylor founded the Australian company in 2007 and served briefly as a director between 2008 and 2009, well before becoming an MP in 2013. His business partner, Tony Reid, was also a director and acted as a consultant on the controversial sale of overland flow entitlements to the government.

The commonwealth environmental water holder, Jody Swirepik, confirmed last week during Senate estimates that the rights bought from EAA have not yielded any water at all.

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Swirepik explained that the entitlement volume was 71,456 megalitres and the long-term average yield should be about 28,740 megalitres.

“Just that indication will tell you that you only expect to get it every couple of years. Since the purchase, there hasn’t been a flood down that system, so no water has become available,” she said.

Under questioning, Swirepik said exercising the entitlement would depend on cyclones in Queensland and there could be a gap as long as seven years before the commonwealth would receive any water.

However, she said the commonwealth environmental water holder was “very supportive of the purchase” because it could benefit the Ramsar-listed Narran Lakes.

The drought has meant there has not been any heavy rainfall in south-west Queensland that would cause overland flows.

The sale was controversial when it was made public in 2017 because the government purchased the water without a tender through direct negotiations with the company, invoking a clause in the purchasing rules that say the government can accept an unsolicited offer in “exceptionally advantageous conditions”.

There have also been questions about value for money and the sale was referred to the auditor general as part of a broader review into water buybacks. EAA immediately booked a $52m gain on the water rights it sold. Following the sale, the two properties were sold to new owners and the original investors were paid out.

There is no suggestion Taylor or Reid improperly influenced the purchase.

The Guardian has subsequently revealed that the main beneficiaries of the sale were a number of foreign investors who held their interest through the Caymans-listed subsidiary. One of these was Pacific Alliance Group, whose chief investment officer, Chris Gradel, was at Oxford with Taylor.

Taylor has said publicly that he resigned all his directorships in EAA and its Caymans subsidiary before entering parliament and that he neither he nor his family benefited from the sale of the water to the federal government. He has said he was not aware of the sale until it was made public. There is nothing to suggest that is untrue.

However, Taylor’s business partner in a number of rural ventures, Tony Reid, was the adviser to Eastern Australia Irrigation, EAA’s Cayman parent company, during the sale process. Reid’s role included providing advice on the volumes of water that the government could expect under the overland flows.

The Guardian has now received a number of documents under freedom of information laws which show the office of the former minister for agriculture, Barnaby Joyce, took an active interest in the controversial water purchase soon after he took over responsibility for water buybacks from the then environment minister, Greg Hunt.

In an interview with the ABC in April, Joyce said the buyback was “negotiated at arm’s length” and he did not set the price or vendor.

The new documents show the minister’s senior policy adviser, Richard Hyett, asked for background information on EAA soon after Joyce became minister and both he and the chief of staff, Matt Coulton, were kept abreast of negotiations with EAA.

The documents also show the Queensland government had proposed buying both the EAA properties in September 2015 to Hunt, but this had stalled when there was a reshuffle of federal ministers in September 2015.

Joyce had publicly opposed water buybacks in the rural press before he became minister because he was worried about how it would impact on the St George area, where he had lived.

Instead the department came up with an alternative plan to buy just a fraction of EAA’s water, consulting with Joyce’s staff about the new approach. The staff worked with the Queensland government over how to sell the idea to their minister, even suggesting new wording for the letter.

Joyce ultimately supported the $80m deal after he was convinced it would have minimal impact on the region.

The documents underscore that the government knew that the water they were about to purchase would only be available intermittently, and that the real object of the purchase was to meet the targets for water recovery under the Murray-Darling Basin Plan on paper only.

“The purchase of these entitlement would marginally constrain production [on the two properties] in higher flow years, but would have virtually no impact under low-flow years when the region is more vulnerable,” the department told the minister.

In other words, there would be no water available under the purchased licences when there was lower rainfall and the two properties would continue to be able to take water from the river under its other higher security licences.

The department said the purchase would only reduce the percentage of land under irrigation from 34% to 25% in high rainfall years, but this percentage reduction would be lower in normal rainfall years.

When the purchase was announced, the then local member, David Littleproud, said: “This is overland flow. According to the independent study we commissioned NC Economics to do, this will mean 2 to 3 per cent of peak production will be lost.”

Nonetheless the department has insisted that the $80m purchase was good value for the taxpayer and would deliver “valuable environmental water”.