Original: It was called Lake Rezaiyeh in the early 1930s after Reza Shah Pahlavi, but the lake was renamed 'Urmia' in the late 1970s.
Simplified: In the early years of the 20th century, it was named Rezaiyeh Lake after the name of Reza Pahlavi, the king of Iran. After the Islamic Revolution, its name was changed back to Urmia Lake.