Cyclically low-intensity monitored lakes

The subprogramme provides an annual overview of the environmental status of Sweden’s lakes and forms the basis for official statistics. The status descriptions of the lakes are used to follow up on environmental quality objectives and for international reporting and agreements, such as the UNECE Convention on Long-range Transboundary Air Pollution (CLRTAP).

We use rotational monitoring stations in lakes to develop and evaluate assessment criteria for the environmental status of Swedish lakes and watercourses.

Sampling

In this subprogramme, water chemistry samples are collected during the autumn turnover. Some lakes are so remote that sampling must be carried out by helicopter.

Scope of the Subprogramme

The investigations in the “Cyclically low-intensity monitored lakes” cover the entire country. However, due to the large number of lakes in Sweden, a selection must be made. The lakes are selected using stratified random sampling from SMHI’s lake register. The selection is limited to lakes larger than 1 hectare, which means that, following statistical analysis, the results can describe the distribution of environmental status across all lakes in Sweden.

The “Cyclically low-intensity monitored lakes” subprogramme includes a total of 4,800 lakes over a six-year period. Each year, 800 of these lakes are sampled. Once all lakes have been sampled over the six years, the cycle begins anew.

History of the Subprogramme

The “Cyclically low-intensity monitored lakes” programme was launched in 2007. Previously, national lake inventories (so-called National Inventories, "riksinventeringar") were carried out every five years.

Since its inception, an additional number of lakes (approximately 500) have been sampled according to the same principles, but as regional initiatives.

The “Cyclically low-intensity monitored lakes” subprogramme differs from the related "Trend Lakes Subprogramme" in that it covers a larger number of lakes, thereby offering greater geographical coverage.

Responsibilities Within the Subprogramme

The Department of Aquatic Sciences and Assessment is responsible for conducting the programme and also hosts the data generated. “Cyclically low-intensity monitored lakes” is a subprogramme within the environmental monitoring programme area Freshwater, and is funded by the Swedish Agency for Marine and Water Management.