I have no idea! Maybe it has to do with your hand?

Could be a chunk error, what is the translation of the biome (top right, above compass) of the white water? Like Perdorogwaith to me. I have seen biome chunks spawning in the middle of other biomes nowhere close to where the normal biome area. (eg. A Nurn chunk spawning in the middle of the lone lands.

The LOTR water is a greyscale to allow for more colors, such as swamp water or jungle water. Sometimes it glitches, but is usually caused by playing with Optifine. If you have Optfinei, set clear water to false.

Oh. The chunk here is white because of this ? Ok, it's more clearer. Thx