Riley Creek iron ore mine proponent Venture Minerals and the state and federal governments are all expected to pursue the group for costs.
It had previously been estimated the bill could be in the order of $200,000, and that was before it was known the state government would want a slice.
The Full Court of the Federal Court yesterday dismissed Save the Tarkine's appeal against federal approval of Venture's proposed Riley mine, near Tullah.
Venture said it now had unencumbered approvals for the mine, although it would keep it on hold for now due to iron ore price levels.
It confirmed it would seek costs relating to the case and previous appeals.
It told the ASX the court decision "validates the robust approval process completed by Venture".
State Resources Minister Paul Harriss said: "Today's decision effectively ends [Save the Tarkine's] relentless and baseless campaign against the Riley Creek Mine and jobs in the North-West and Venture Minerals can now get on with the job."
"Riley Creek is a key project for Venture in the North-West, which, along with the Livingstone mine, will allow the company to generate capital in order to establish the longer term Mt Lindsay operation and create jobs in the region."
He said it was estimated Mt Lindsay would provide about 200 jobs when operational.
The state did not pursue costs in an earlier incarnation of the legal battle as it had not been a party to the case.