SALT LAKE CITY (AP) — Authorities say toxic levels of a cyanobacteria have been detected in a Utah river for the first time after a dog suffered seizures and died. The dog was at Zion National Park’s Virgin River. Public health officials in the state have since cautioned people against swimming or letting their animals enter the river’s North Fork. The river lows out of the park and through several towns. Park spokesman Jeff Axel says the dog died July 4, an hour after ingesting algae in the river. Most communities along the river have stopped using it as a source of drinking water after the death.