Following the closure of Collombey refinery in 2015, Cressier is Switzerland's only operating crude oil refinery. This sharp decline in domestic refining capacity has left Switzerland more dependent on oil product imports, primarily sourced from the ARA trading hub and barged up the Rhine river. The Swiss market can be volatile. Emergency fuel stocks were released in 2015 and 2018 when very low water levels on the Rhine restricted the movement of barges to the upper regions. These incidents have highlighted Switzerland's exposure to increasing physical supply risk and the impact of climate change on the Rhine as a vital European transport corridor. Demand can also be affected by unseasonably cold or warm weather, causing short-term fluctuations in heating oil consumption. The Swiss retail fuel market is characterised by two distinct segments: automated unmanned sites with a focus in low overheads and offering discounted fuel prices, and full service stations with convenience stores.