A 52-year-old woman is facing drugs and weapons charges after a member of the public alerted police to her erratic driving behaviour.
The Rununga woman will appear in Greymouth District Court today, Senior Sergeant Allyson Ealam says.
The woman was seen driving erratically on State Highway 6, south from Westport on Monday by a member of the public who alerted police.
Police officers stopped her at about 1.30pm and she failed a drugs test.
The woman faces charges of driving while under the influence of drugs, possession of drug utensils, possession of methamphetamine and cannabis resin, possession for supply of LSD, and possession of an offensive weapon.
Police are praising the person who tipped them off.