"On the other hand, the 22 hectares to be removed from the Ruahine Forest Park has been heavily logged in the past, is partly infested with weeds such as willow and Darwin's barberry and contains a former house site," he said.
In reaction a critic of the deal, Dan Elderkamp, who is co-Chair of CHB Forest & Bird, said he was disapppointed but it was expected.
"Forest & Bird will have to look at legal options and possibly challenge it," he said.
Mr Sanson said the decision followed a thorough and open public process and the careful assessment of the ecological values of both sites.
The Director General has decided to revoke the protected status of the 22 hectares of Ruahine Forest Park to enable the exchange to take place.
Under the Conservation Act, proposed land exchanges must result in an overall conservation gain for public conservation land and promote the purposes of the Act.
"I believe this land exchange well and truly meets that test," he said.
Mr Sanson the land exchange was conditional on the Hawke's Bay Regional Investment Company undertaking extra conservation programmes to help eradicate wilding pines from the exchange land and to restore whio/blue duck habitat.
The exchange is also conditional on the Ruataniwha water storage scheme going ahead.
In a separate decision, the Hawke's Bay Regional Investment Company will be required to trap and transfer native fish species present at the dam site.
Full details of these decisions, including ecological reports, are available at www.doc.govt.nz/ruataniwha