Vandals did approximately $1,000 worth of damage at Little Redwood Bar on the south bank Sept. 6.
The damage was discovered Friday night when Forest Service employee Otis Newman went to the site to do routine maintenance.
He discovered two portable toilets destroyed and four others damaged.
Witnesses told Newman that at least three vehicles ran over the toilets causing the damage, said Resource Assistant Jerry Darbyshire.
The toilets are plastic structures and the plastic split and broke, said Darbyshire.
The witnesses got the license plate number of one of the vehicles. The Forest Service is investigating that plate, which returned to an address in Tigard, said Darbyshire.
He said it is unknown if the same people who recently vandalized Miller Bar are involved. He said local people could be involved, but the Forest Service is still investigating.
Weve had trouble off and on for the last two summers, said Darbyshire. Weve given tickets to several juveniles. Its hard to tell whos involved, he said.
The Forest Service was planning to remove most of the toilets for the winter season. It will replace the damaged toilets before the next summer season at a cost of about $1,000, said Darbyshire.