One of the two rivers flowing into the heart of Iowa that provide 500,000 residents with drinking water is slowly being infiltrated by toxic algae as temperatures climb.

The other river is drying up and dipping to dangerously low levels as a historic drought grips the United States.

The Hawkeye State’s plight underscores why climate change is seen as a threat multiplier for the drinking water sector — from cratering water levels and drought to floods and extreme weather. And then there are toxic algal blooms that can kill fish, foul water, and threaten human and ecosystem health.