If the name is given as a noun, jezero precedes it (Jezero Gazivode), if the name is given as an adjective (usually with the -ko suffix), jezero comes after (Vlasinsko jezero).
When a name is used as a noun, "Jezero" comes before it (like "Jezero Gazivode"), but when it's an adjective (often ending in "-ko"), "jezero" follows after it (e.g., "Vlasinsko jezero").