Southland fire crews are hoping to have a forestry fire in the Awarua Plains under control this morning.

The blaze has torn through a harvested area, and ground crews have finally been able to get close.

This morning it was threatening power lines that supply the Tiwai Point aluminium smelter.

Southern Rural Fire spokeswoman Sally Chesterfield says crews are getting on top of it.

"That's burning in some logging flash and it's surrounded by green grass paddocks so it's not able to travel too far at this point. There's also some smaller power lines which the fire is currently burning under. We have got the Tiwai smelter people on site."

She said it shows the effect wind can have.

"This was started by someone who is a very careful burner who had burnt two weeks ago and had very methodically checked their fire to make sure it was out and those winds blew his fire back into life and then blew the fire into larger piles of material."

And the fire burning near Dipton - which is about two thirds the size of the Marlborough fire - is still going but is largely contained.