- Name of measurement site: Koiransuolenoja stream
- Location: Hämeenlinna, Lammi, Pappilakylä
- Catchment area: Lammin Pääjärvi, Koiransuolenoja sub-catchment (6.2 km2)
- Coordinates (ETRS-TM35FIN): P:6769913, I: 393418
Koiransuolenoja catchment is the smallest of the five largest sub-catchments of lake Pääjärvi. Agricultural fields contribute 25% of the area. Peatlands are composed of peaty forest; which comprise < 5% of total catchment area. The landscape is a mosaic of forest, fields, rocks and eskers. The highest altitude is 150 m a.s.l. and the area is situated in the northern part of the catchment. Soils are formed from clayey silt, sandy gravels, moraine and organic soils. Fields situated close to the stream contain fine soil material. The main stream channel follows highway 12 for >1 km. The length of the main channel is 5 km. The measurement point is situated 0.83 km upstream from lake Pääjärvi. On-line measurements were started in January 2013, and weekly samples for water chemistry have been collected since 1991 during the open water season and since 2000 year-round.