Natural Resources Wales has launched an investigation after finding human waste in a stream. .
After his family discovered it, broadcaster Will Millard tweeted video expressing his disgust.
When the feces were discovered in the River Edw in Llanbadarn y Garreg, Powys, the Hidden Wales presenter declared that he was "incandescent.".
The 40-year-old claimed he made the dreadful discovery while his kids were having fun in the water.
My sister and her children are also present, he said. When my brother-in-law suddenly walked up into this pool and said, "There is a load of human poo just off the bridge," all four of our children were already in this portion of the river, catching stone loach and enjoying the river. ".
He claimed that some of the riverbed's "sandy-looking" patches were actually made of trash.
There is a ton of it, according to Mr. Millard.
"All I can think of is that someone came along, probably with a chemical toilet or something, and dumped it off the bridge after camping nearby.
It's utterly repulsive. It's terrible for our children because they have all had to return home and clean up, but it's also terrible for the wildlife and the environment. ".
Mr. Millard referred to the actions as "disgraceful.".
He declared, "I believe I have never seen one of the worst things in a Welsh hill stream.".
"It's disgusting. ".
Natural Resources Wales acknowledged the issue had been brought up and was the subject of an investigation.
"We had officers on site soon after it was reported and we carried out checks at the location in question as well as upstream and downstream," said Jenny Phillips of the south Powys environment team.
"The investigation is still ongoing, but we believe this to be an isolated incident. No signs of distressed fish or other wildlife were observed by our officers. ".
High levels of organic matter in human waste decrease water oxygen levels and endanger aquatic life.
The ammonia it contains, according to Ms. Phillips, "can be toxic to fish and macroinvertebrates in high concentrations.
"The increased nutrient levels could lead to uncontrolled algal and plant growth that harms the environment and the water supply. ".
She urged people to properly dispose of their waste.