Eutrophication is a big problem in water reservoirs. A study in Iran looked at the eutrophication levels in Sahand dam. They measured different factors like chlorophyll and phosphorus to see how eutrophic the water was. The dam had moderate to upper-mesotrophic conditions, with some areas close to being eutrophic. The worst spot was near Qaranqu River due to lots of suspended particles from erosion. The researchers found that the reservoir needs urgent action to stop eutrophication.