Thursday, June 13, 2013 | 7:33 a.m.
Officials say they're welcoming swimmers back to the Overton Arm at Lake Mead after finding no dangerous toxins in the water.
Park spokeswoman Christie Vanover said Wednesday that officials still haven't determined the exact cause of the foamy substance that prompted their no-swim advisory over the weekend.
But she said the water temperature and pH levels were normal, and no toxic algae was found. Officials said the brown foam extending about eight miles from the mouth of Virgin River to Echo Bay may have come from proteins released by dead algae.
Authorities also became concerned over the weekend when they spotted dozens of dead carp in the area.
Vanover said the cause of the fish die-off isn't clear, but noted that no more mass fish deaths have been seen since.