The Erken station and lake is located in the Uppland area in east-central Sweden surrounded by a hemi-boreal landscape. The bedrock consists mainly of gneiss and granites overlayed by glacial and postglacial clay deposits. The extensive environmental monitoring program for Lake Erken includes both manual and high-frequency automatic measurements. The program includes one of the longest available measurements series of water temperature and water chemistry as well as plankton community analyses, including sampling stations in the lake as well as all in- and outlets. More recently, greenhouse gas flux measurements also became part of the monitoring programme. The field station was founded 1946 and belongs to Uppsala University. It is running all year round with a staff of about ten people. The station is also part of the Swedish Infrastructure for Ecosystem Science (SITES).