It's peak season on the Whanganui River, with about 100 people a day finishing river trips at Pipiriki.
About half of them are canoeists, with the rest "day trippers" who get rides in jetboats.
The campsites and huts have a booking system, and are at capacity.
Numbers using the river have been increasing about 15 per cent a year for the past few years, senior Conservation Department ranger Jim Campbell says. They have risen from about 4000 to about 9500 canoeists a year.
There are even more who are day visitors - many of them international tourists who don't have four days to paddle through the bush. All those people need a lot of toilets.
On Tuesday's 1 News, Maori complained that some visitors were defecating in the bush rather than using toilets.