1. The upper layer of water in a stratified lake or reservoir, characterized by relatively warm temperature and well-mixed conditions.
Usage: technical; limnology

Examples

• The epilimnion of the lake warms significantly during summer months.
• Fish in the epilimnion have access to abundant oxygen and sunlight.
• Temperature gradients separate the epilimnion from the deeper hypolimnion.
• Algae blooms often occur in the nutrient-rich epilimnion.
• The epilimnion's depth varies depending on the season and weather conditions.