Access to clean, debris-free water is essential for equine health, but contamination can be caused by everything from insects to natural disasters.

Horses who have access to creeks and ponds may ingest poisonous cyanobacteria from a blue-green algae bloom while drinking. But even horses with access to only water in man-made receptacles aren’t completely safe from harm. Blue-green algae can also bloom on stagnant water in troughs and buckets, reports The Horse.