These intersections come under the jurisdiction of the NZ Transport Agency (NZTA) which is behind the push to expand the council bylaw to cover highway intersections.
NZTA Northland highway manager Brett Gliddon said the agency was working with the council to delegate powers which would allow its bylaw for window washers to apply to state highways in the district.
"Whangarei District Council would need to agree to have the powers delegated to them and a delegation agreement put in place," Mr Gliddon said.
"The enforcement of the bylaw dealing with window washers or any other dangerous or illegal activity on the road or roadside would be a police matter.
"The agency understands window washers are causing concerns for people and believes the best way to discourage them is for people not to pay or engage with them."
Whangarei Mayor Sheryl Mai said the two parties were grappling with what was a predominantly seasonal issue.
The parties' jurisdictions did not combine well and no one wanted to jump to a response that could backfire.
"The issues are many. They include costs, legal jurisdiction, public processes and safety.
"Anything anyone does to respond to window washers has to be correct under the law, and fair and we don't want anyone hurt," Ms Mai said.
"There is a risk of a washer being bowled by a car, hurt or killed, and a driver being put in a terrible situation, too."
She said the young people involved in window washing knew they could not be fined at highway intersections, although they tended to scatter if police or council staff showed up.
"All this needs to be worked out, and that requires legal opinions, and drafting of responsibilities and agreements and allocation of funding," Ms Mai said.
In the meantime the council would continue to respond to complaints.
"I hope that we will have a framework set up to come into action next summer, and I will be calling a meeting this week to see how quickly we can advance progress.
"Until then I ask for people to be safe, responsible. Don't pay, if you don't want the service."