A farmer has seen red after water seeping onto his land turned his field orange.
Terwyn Tomos farms land in Bontddu and along the Mawddach estuary between the Barmouth road and the sea.
Part of his land joins a picnic area called Farchynys which was formerly used as a waste dump.
Mr Tomos said he reported the problem to the authorities but as yet nothing has been done and the situation is getting worse.
"When I first talked about this I went to the county council and they sent the Environment Agency to take samples but they didn't come back to me at all," said Mr Tomos.
"What's bad about it is the National Park have known about it for years and have done nothing.
"Last year I only grazed the sheep there for twenty seven days but now it's just one big bog.
"I can't prove that it comes from the dump. They should test the water before it goes into the dump and then after when it comes out.
"At first the water looks clean but when I walk through it it turns red and leaves a red slime on the grass.
"Once it's their I take the sheep away from it straight away," he said.
