Minecraft wiki entry for Development_versions, associated text: Small lakes features are no longer placed in dry and hot biomes (desert, savanna, badlands).
Reduced the number of lake feature placements in other biomes.
Water springs can generate in more types of blocks such as dirt and snow, increasing the likelihood of small mountain streams and waterfalls.
Reduced the amount of shattered terrain and shattered savanna biome, replacing some of that space with flatter beaches instead.