Owners not picking up after their dogs

I am a resident in Howick and live off Somerville Road. I use the Mangemangeroa Reserve daily to take my dog for a walk however I am getting more and more frustrated about the number of poos I see that dog owners have not picked up.
This makes non-dog owners annoyed and frustrated with dog owners and I feel it’s just a matter of time before they complain and dogs will be banned from the reserve. I’m asking dog owners to do the right thing.
Gillian Jones, Howick