The school, which has a roll of 43, have done a number of clean-ups along the river, including a couple of "big efforts" last year.
He said the pupils put their heads together to come up with some ways to solve the issue of dumping and came up with the idea of signs.
"That was a strategy they thought could help encourage people not to dump rubbish."
Three pupils gave a presentation in the public forum at a Whangarei District Council meeting earlier this year to ask for help with their signs.
They were "stoked" when the council agreed to fund them.
Mr McQueen said the pupils designed the signs themselves and didn't want a negative 'don't dump rubbish' sign. Instead the signs have a picture of the river itself and a positive message.
"They wanted to put an emphasis on the beauty of the place and let that be the motivation."
Mr McQueen said his pupils were amazing through the whole process.
"We've got it to a place now and it's looking mint."
He said the signs are about 1km away from the school, at a popular swimming hole.
Mr McQueen said the clean-up was part of a project to foster identity in the students and make them proud of where they're from.
"Education has the ability to shift paradigms and shifting paradigms is important in regards to behaviour."
He said the pupils will continue to monitor the river.
"We're optimistic it will have a positive impact on people's decisions."
Mr McQueen said the pupils were proud and blown away to see their idea come to fruition.
Whangarei District Council waste and drainage field officer Grant Alsop said it is "an awesome little school".
He was supportive of getting the youngest generation to be passionate about the environment and lead the way in caring for it.
Mr Alsop said he was really proud of them for what they are doing.
