Trend watercourses

The subprogramme provides an annual overview of the environmental status of Swedish watercourses and serves as a basis for official statistics. The status assessments are used to monitor progress towards environmental quality objectives and for international reporting.

We use data from the Trend River Stations Subprogramme to support the development and evaluation of assessment criteria for the environmental status of Swedish rivers and streams.

Sampling

Within the subprogramme, water chemistry is sampled monthly. Benthic invertebrates, diatoms, and fish are sampled annually.

Scope of the Subprogramme

The Trend River Stations Subprogramme includes a selection of 67 watercourses across Sweden. These trend rivers are chosen for being unaffected by local pollution sources or intensive land use, making them suitable reference sites for assessing the environmental status of more impacted watercourses.

The subprogramme covers watercourses of widely varying sizes, with catchment areas ranging from approximately 1 km² to over 10,000 km².

The Trend River Stations Subprogramme differs from the closely related River Mouths Subprogramme in its focus on smaller inland rivers and the absence of any requirement for outflow to the sea. In addition to chemical sampling, the trend stations include biotope sampling. All trend rivers have established fish populations, primarily brown trout.

History of the Subprogramme

The Trend River Stations Subprogramme began in 2007. Previously, similar monitoring was conducted through the Reference Watercourses Programme, which has been in operation since the mid-1980s. Between 1995 and 2006, the monitoring was conducted under the name Time Series Watercourses ("tidsserievattendrag"). Some rivers were added as recently as 2007, while others have continuous time series data spanning over 40 years.

Responsibilities Within the Subprogramme

The Department of Aquatic Sciences and Assessment is responsible for implementing the programme and hosts the generated data, except for fish data. The Trend River Stations Subprogramme is part of the Freshwater programme area within Sweden’s national environmental monitoring framework and is funded by the Swedish Agency for Marine and Water Management.