Monitoring of inland waters' quality in Finland

Data on water quality of rivers and lakes have been collected in Finland since the 1960's. The current monitoring is a mutual project of the Environmental Authorities composed by re-designing and merging the earlier nationwide monitoring programs with the programs of the Regional Environment Centers. The program aims at a balanced sampling of natural water body types. The frequency of sampling varies: some of the sites are sampled intensively 4 - 12 times a year, whereas some sites are sampled every three, six or 12 years. The state of waters is monitored by using biological, chemical and physical variables. Variables monitored differ between sites. All the data produced are stored in the common HERTTA- data bank of the Environmental Authority.