Toledo Residents are Advised Not to Drink the Water

Excerpt from video:  Nutrients, like nitrogen and phosphorus, found in sewage and fertilizer, overfeed the algae, and the lake, made warmer by climate change, provides a comfortable environment for the algae to thrive..  (The link is to "Battling the Bloom: Lake Erie", which has just 813 views.  Should be seen by millions.)

The primary source is agricultural run-off.

[Mayor D. Michael] Collins to update water crisis after 10 p.m.  (Toledo Blade, 8/3/2014)

Wondering if the advisory is really necessary?  You'll want to click on the previous link and take a gander at the glass of lake water.