In order to track the environmental condition of Lake Mälaren, water chemistry, phytoplankton, zooplankton and invertebrate fauna are sampled annually in the lake's different sub-basins.
Data can be obtained from Miljödata MVM. Use the links below to get directly to Lake Mälaren's sampling stations. You may need to adjust the time period and desired parameters. The earliest samples in the database are phytoplankton samples from 1955.