The review also stated if the council withdrew from the scheme, this would cost a write down of the $19.5m already invested.
It could also mean the council would have to refund $7m from the Crown.
When asked how confident he was that the scheme could proceed, Minister for Primary Industries Nathan Guy said it was too early to say.
"If the dam doesn't go ahead there will definitely be pressure on farmers and growers who need a reliable, regular supply of water. At this stage I'm not aware of any alternative, viable proposals that could do a similar job."
Views on the future of the scheme are divided for those sitting around the Hawke's Bay Regional Council - the majority of whom were seemingly elected to council with an anti-dam mandate.
Council chairman Rex Graham said he felt it was "very difficult to recover from this point, and all costs related to this project should be stopped until a sensible way forward is agreed to".
"The dam will be shelved, there's no place for it," Napier councillor Neil Kirton said. "It's just a manner of trying to rescue elements of it to go forward, because we've still got the large challenge of implementing Plan Change 6.
"What we're now needing to do is take stock and plan the future without the dam."
Some councillors are more positive - like Wairoa councillor Fenton Wilson, who said the ruling was "frustrating and it's certainly slowed the job down ... but I don't quite see the view of some of my colleagues that it's the death knell".
"As far as I'm concerned it's all still alive. The regional council is really only talking about its investment in the dam. The consents are still alive, the other investors are still sitting there, their due diligence still stacks up, watch this space."
With "$20m on the table" others, like regional councillor of Napier Paul Bailey, and regional councillor for Central Hawke's Bay Debbie Hewitt, are waiting for HBRIC advice on the best course of action.
Its acting chief executive, Blair O'Keeffe, said they were reviewing the project, "with decisions on next steps still being evaluated".
Ms Hewitt - who has called the ruling a "tragedy" for the residents of her ward - said the council needed to be prudent, and not make any quick decisions.
"Let's not be reckless about this. Let's take a deep breath and hear from the investment company before we go marching off."
Ngaruroro councillor Peter Beaven said HBRIC's report could present more options: "maybe there's something we've missed, maybe HBRIC have got some alternative plan they can put in front of us".
"The door's still open for that to happen before we make a final decision but the reality is, it's very difficult for us to see any sensible pathway forward that doesn't involve years of uncertainty, and I think everybody deserves better than that."
At this stage, it has been said there are two possible avenues which could allow the swap to go ahead in future - one of which would be securing access to the land, by becoming a requiring authority under the Public Works Act, as HBRIC had suggested late last year.
A requiring authority can use special provisions in the RMA to request the Crown acquire or take land on their behalf.
However, the majority of councillors have said they would not support any attempts to acquire the land under the act, and last week pushed through a recommendation that council take this stance.
"It would be highly inappropriate for a council charged with protecting the environment to use the Public Works Act to secure this land when the Supreme Court has ruled that this is not lawful," Mr Graham said.
However, Mr Wilson - who voted against the recommendation to not support the Public Works Act - said he found this sentiment "hard to follow" as DoC were advocating for the swap.
"Surely as responsible governor we'd want to examine all options to maintain the integrity of that investment. To rule one out without even knowing what it might look like was reckless and foolhardy in my view."
The other avenue is a change in legislation - this was suggested by the prime minister, and echoed by Conservation Minister Maggie Barry hours after the Supreme Court ruling was released.
""We want to clarify the law so that the Conservation Act allows for land swaps that improve conservation outcomes while ensuring we also balance the needs of regional economic development," she said.
With the Supreme Court ruling being 5-4, Ms Hewitt said the process had shown there was a "huge lack of clarity" that needed to be addressed.
However, Forest & Bird chief executive Kevin Hague said if the law was changed, "We and our members and supporters are certainly prepared to fight any law change that allows for destructive developments to take place on conservation land."
Given the proximity to the general election, it has been questioned whether this could occur - depending on who was in government after September, and what their priorities were. Even if a law change were to occur, the timeframe given by council staff could take between nine months, to two years.
As Ms Barry said any law change "will not apply retrospectively and will therefore not affect the Ruataniwha Dam decision", some suggested this meant DoC would have to go through the land swap process from the beginning.
Both options could add years to the dam's progress - Mr Beaven noted that depending on how long it took, a number of elements of the scheme would have to be renegotiated.
"Even if you want to go ahead and do this, it'll be a completely new set of circumstances and a completely new project. It's not realistic for us to sit around for a long time, several years in the hope that may or may not happen," he said.
"It's not fair to farmers who will be sitting on the sidelines waiting and it's not fair for our ratepayers because it's not a sensible thing to do with the $60m."
Although some councillors are positive the scheme can still proceed, Hastings councillor Tom Belford said he thought there were at least six councillors wanting to "get on with other business".
He was waiting for the HBRIC advice, but said "I can't see any chance that the [council] is going to sit on $60m and leave it allocated to a $300m dam in CHB which is never going to happen.
"We're going to move on. There are a lot of other needs that this region has, there are a lot of other ways to use $60m and that's where we're now headed."
Looking forward, the staunch dam said the best time to discuss this would be during the Long Term Plan process.
This could also be a time to discuss alternatives if the scheme were to be shelved, or even abandoned - although there is doubt these could offer the benefits the scheme would have.
Should the council propose another idea that was not harmful to the environment - and development occurred within environmental limits - Forest & Bird would not be opposed to it, Mr Hague said.
Suggestions floated to Hawke's Bay Today ranged from on-farm storage, to council providing farmers with financial or regulatory support. Mr Belford said they would have to look at "any realistic opportunity".
Whatever action is taken, Ms Hewitt said the council had an obligation to CHB residents who believed Plan Change 6 and the RWSS consenting process had been "intrinsically tied".
"To address the environmental issues in CHB, water storage was the key solution ... I don't think they'll be addressed without water storage.
"There are a lot of people who have held out for this as a farming practice going forward," Ms Hewitt said. "They've held on to it for a very long time as a vision and it is a legacy project so they've brought their families on board with them."
Although the regional council will be meeting next week, it is understood HBRIC may not be advising them until next month.
Councillor Alan Dick could not be reached for comment.