The 36-year-old's had her licence suspended and is due to appear in court.
The Northland Regional Council wants help but urges people to "always consider your safety".
"It reinforces the dangerous message… that a small, noisy group can illegally camp on someone else's land and be rewarded for it."
The woman has been charged with possessing an offensive weapon.
Police said a 50-year-old man has been arrested.
The brawl broke out at Dargaville High School.
Police wouldn't confirm if the teenager was driving the car.
The $40 million project, which got underway in earnest in 2021, includes a roundabout on the Kāeo side of the river to improve traffic flow.
Police were notified of the possible leak at around 9:50am Monday.