Contaminated Harmful Water

In lush cave biomes, there's 5% chance that a lake will be toxic, giving poison effect for 4 sec on contact. Their color is lime green and form bubble particles. Chance happens only in lower lush caves and no mobs will spawn there.

What is their usage ?: You can scoop up with a bucket, bottles or even make poisoned tipped arrows which will drain it away. (Similar to potion effect water on cauldrons.) Also putting toxic water over lava could be another source of obtaining crying obsidian. However unlike water they can't be infinitely made, but made could be artificially made by throwing splash poison potion directly at the clean water. Contaminated water will not mix with clean water.