Mr Cox told the tribunal it was difficult to attribute an economic value to the use of specific water.
"It is much easier to determine the overall value of multiple water uses as part of an integrated system such as an State Owned Enterprise (SOE).
"Owning part of an SOE therefore provides a pragmatic mechanism for obtaining fair value for water currently used in hydro and geothermal power stations, as well as future power stations."
However, Mr Cox also warned that "Continuing with the partial sale while the issue of
ownership of water remains unresolved will reduce the value of the companies and thus share price".
Mr Cox said uncertainty regarding the ownership of water resources may affect the confidence of investors in new hydro or geothermal power stations and those considering purchasing shares in an SOE.
"Investors in power stations evaluate the risks to their investment that could arise from possible future events and the rights to use water from rivers or geothermal
reservoirs are a critical consideration."
Mr Cox's presentation finally prompted some questions from Crown lawyers who had been challenged just an hour or two earlier by a claimant over their silence so far during the hearing.
Crown lawyer Paul Radich briefly questioned Mr Cox on whether uncertainties around Maori claims over water being discussed were any different from the Treaty risk already disclosed in resource consents. Mr Cox said he believed they were different as resource consents dealt with environmental issues rather than proprietary rights.
Crown challenged
Earlier today, the Crown was challenged for its silence so far during the urgent Waitangi Tribunal hearings.
Speaking for Auckland iwi Ngati Te Ata this morning, Roimata Minhinnick challenged the Crown over its silence so far during the hearings.
Crown lawyer Kieran Raftery stood and addressed Mr Minhinnick saying the Crown did not challenge his story of how his iwi and others came to have customary rights over resources.
"We accept there are rights and interests", he said.
However, he told the tribunal at Lower Hutt's Waiwhetu Marae that the Crown would put its views forward later this week.
"We accept your challenge."
Listening intently to this morning's proceedings was Maori Council co-chairman Sir Graham Latimer who is the lead claimant. The tribunal is expected to come up with its recommendations on the claims by the end of the month.
Prime Minister John Key has said his Government may ignore it, should its findings back the claimants and simply continue with the sale of up to 49 per cent of Mighty River by the end of November.
However, the other Maori Council co-chairman Sir Eddie Durie has said the council will likely take the matter to the Court of Appeal should the Government ignore a tribunal decision in favour of the claimants.
Sir Graham this morning said he expected the council's battle to continue for months to come.
