The monitoring programme Trend watercourses will provide a measure of the state of locally unaffected watercourses in Sweden. The dataset contains water chemistry and biology from 67 watercourses evenly distributed throughout the country.
The monitoring programme started in 2007, but most of the stations were part of the previous reference water programme and have been monitored for water chemistry since the mid-1980s. Some of the water bodies have been monitored for over 40 years.
The current monitoring programme samples:
- water chemistry monthly in all 67 streams
- benthic fauna and diatoms in 48 streams, at least once a year
- fish in 29 streams annually.
As the streams are relatively unaffected by point source discharges, the programme helps to establish a reference network for monitoring environmental status and impacts in small and medium-sized streams across the country. In the 29 stations where fish are sampled, there are populations of trout.
The results of the monitoring provide input to the EU Water Framework Directive and data to the European Environment Agency (EEA), are also used as baselines for assessing changes in more impacted areas, and inform the further development and evaluation of assessment criteria and environmental quality objectives.
The programme's long time series are of particular value for analysing the effects of climate change and for monitoring the recovery of lakes from acidification.