Stable silicon isotopes were measured on water samples taken in March, June, July, August and September 2019 in Lake 850, Northern Sweden.Water samples for stable Si isotopes were sampled in HDPE acid-washed 125ml Naglene bottles and filtered directly in the field through 0.45μm Sterivex filter and further acidified using HCl to pH 2. Stable silicon isotopes were performed on cation-exchange collumn cleaned (Georg et al., 2006) samples using MC-ICP-MS at Vegacenter, Stockholm.