The purpose of this study was to examine whether an inventory of the vegetation overgrowth could be used to indicate a locally nutritional impact. The study was conducted at Märstaån where the water runs through a number of agricultural lands that could lead to an increased amount of diffuse emissions of nutrients. The vegetation overgrowth in the water was also studied in relation to shade, meandering and water flow effects on the vegetation. With this method, no definitive conclusions could be drawn. Where the water was shaded, no vegetation overgrowth could be found. Therefor trees should be planted to prevent any future overgrowths. The majority of Märstaån is straightened and should get an increased meandering to lower the water flow. The water pond in Steningedalen could also be more effective by lowering the water flow. In the future, more extensive studies should be conducted in the purpose to find other substances in the water that comes from point sources in the area.