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Lake Lucid (Japanese: アラタマ池 Aratama Pond) is an anime-exclusive location found in between Ecruteak City and Olivine City. It appeared in The Joy of Water Pokémon.
Lake Lucid in its original state
It is home to a family of Nurse Joys who are famous for their methods of cleaning and purifying the waters of the lake. Over the years, they studied the effects of the pollution on Pokémon and made projects to clean the lake, publishing books with season-themed titles, starting with Spring, on their endeavors.
Eventually, the purification program made the lake clear and clean, to the extent Water-type Pokémon came to live there, and the Lake Lucid Pokémon Center was built to care for them. However, the third generation Nurse Joy was terrified of Water Pokémon, causing Misty to react with anger. Eventually, Joy slowly overcame her fear of Water Pokémon with the help of Misty and the others.
Pokémon seen in Lake Lucid