"Heatwave [allegedly] turns America's waterways into rivers of death"

Heatwave turns America's waterways into rivers of death - Nature - Environment - The Independent

"It's pretty safe to say that what we're seeing here is the warmest that we've seen in Lake Superior in a century," said Jay Austin, a professor at the University of Minnesota at Duluth. The average temperature recorded for the lake last week was 68F (20C). That compares with 56F (13C) at this time last year.

It is a boon to shoreline residents who are finding normally chilly waters suddenly inviting for a dip. But the warming of the rivers, in particular, is taking a harsh toll on fish, which are dying in increasingly large numbers. Significant tolls of fresh-water species, from pike to trout, have been reported, most frequently in the Midwest.

US NODC Coastal Water Temperature Guide

70 to 78 degrees Fahrenheit is the range where most folks feel "comfortable" swimming

2010: Deep freeze kills millions of fish in Florida

“I was so shook up, I couldn’t sleep,” said Frezza, an ecologist for Audubon of Florida and an expert flats fisherman. “Millions and millions of pilchards, threadfin herring, mullet. Ladyfish took it really bad. Whitewater Bay is just a graveyard.”

2010: Cold Kills Millions of Fish in Bolivia

Tropical parts of landlocked Bolivia, where rivers normally flow in a 20 C (68 F) environment, experienced 0 C (32 F) air temperatures that killed 6 million fish.