Her mum Sanne Coulthard, came up with the idea of writing to the council instead.
Napier City Council workers cleaned up the plastic last week, but also launched a Facebook campaign to get in touch with Olivia.
On Friday Olivia met with council officers Cameron Burton, Caitlin Egan and Andrew Gass, who look after the waterways in Napier.
She had plenty more ideas for them to help protect the waterways, including providing more rubbish bins so people could dispose of their waste properly, wheelie bins for recycling so plastic didn't blow away before it was collected, and signs asking people not to throw their rubbish in the creek.
Coulthard said it was great to see her daughter taking such an interest in the environment.
"It's really cool, you know, I didn't have to say much and off she went!"
Burton said it was inspirational that Olivia was so in tune with the environment at such a young age.
"We wanted to encourage what she was trying to achieve through giving her the attention we have."
They presented her with a certificate to say thank you for being an environmental warrior.
Burton said it was important for people to realise that all waterways in Napier led into the estuary.
"The stormwater channels, when there are instances of pollution, like Olivia has seen, let us know, because we can't be everywhere at once.
"Hopefully bit by bit we can make a difference."
