Estuaries are very special. They act like a natural filter that helps clean the water before it enters the ocean. But we don’t fully understand how this works and how the processes change throughout the year. So, for a whole year we took samples from various sites along the Western Scheldt estuary. It’s a restored estuary that used to be very polluted. The samples were taken from freshwater, marine water, and brackish water. We analyzed them for several nutrients. We wanted to check how the concentration of nutrients changes in different seasons. Thankfully, our results show that the Western Scheldt estuary is healthy! We discovered that each section of water works differently as a filter. We also found out that temperature is a very important factor in how they work.