Tenderers shall survey the state of the environment, particularly with a focus on PFAS pollution, in the lower part of Randselva and Tyrifjorden. The study comprises sampling and analyses of relevant fish, lake sediment and benthic organisms in the same stations, which are used in the report M - 863 "Source tracing of PFAS in Tyrifjorden". It is particularly interesting to measure and assess any effects of extreme precipitation on the spreading of pollution through the food chain and particles in Tyrifjorden. The cost limit for the procurement is NOK 1,500,000 excluding VAT. Tenders shall not exceed this total cost.