Documents issued by the Department of Conservation show energy companies paid $13 million during the past two decades in agreements to help them obtain resource consents.
The money was paid by energy companies including Contact, Meridian, Genesis, Transpower and Mighty River Power.
The agreements were used to help offset the environmental impacts of hydro schemes, wind farms and irrigation projects since the 1991 Resource Management Act.
DoC received more than $8 million and another $5 million was paid to trusts which allocate mitigating work to community groups, councils and DoC.
Director general Al Morrison says the agreements were not kept secret.
The Government says it's comfortable with the agreements but DoC must be more proactive about ensuring the public is fully aware.