Club secretary, Gary Clark said: “Fly tipping is a perennial problem in the countryside but dumping toxic waste into a river creates serious environmental damage.
“This little stream provides habitat not only for trout and other fish but otters, kingfishers and numerous other species, some of them rare and endangered.
“The tyres were dumped several weeks ago and we had to get them out quickly as the next storm would have sent them all downstream to decompose over decades.
“Our rivers are all suffering from pollution caused be agricultural runoff and sewage discharge so the last thing they need is to be turned into a municipal dumping ground.”
The incident was reported to the Environment Agency but no action was taken.
Mid Devon District Council normally deals with fly tipping but could not respond as the tyres were in the river.
“Eventually we got MDDC to agree to collect the tyres for disposal if volunteers recovered them from the river.
“If anyone has any information regarding this criminal act they should report it to the police.”