A council has stepped up patrols on a public footpath in response to a "surge" of complaints about people using it as a toilet.
Ryedale District Council said it had received a series of reports of human mess on the path alongside Priorpot Beck in Norton, North Yorkshire.
It has failed to locate any culprits despite launching an investigation in 2019.
Council leader Keane Duncan said it was "disgusting behaviour".
Since 2019, council officers have been monitoring the site to try and find the culprits but do not have enough evidence to identify the people responsible, the authority said.
Following renewed complaints of "human fouling" in the area, plus an assault in December, an appeal has been made for information.
Mr Duncan said: "Complaints of human mess have surged in recent months. Dog mess, littering and anti-social behaviour are also an issue.
"Our officers will be out on regular patrol in and around the area to provide public reassurance and to help deter offenders.
"This disgusting behaviour should not be happening. It is a risk to health and it needs to stop."
Enforcement officer Helen Patterson said: "We are taking it very seriously, and what we would ask is that if there are any residents or businesses in the local area that feel they can provide us with any information that may be useful to our inquiries, to send those to us."