The expected increase in the frequency and intensity of extreme weather events and high flow rates caused by climate change may cause re-suspension of pollutants stored in sediments. It is a serious concern, causing aquatic biodiversity loss in rivers, lakes and wetlands, hampering human use of the water (e.g. drinking water, recreation, fishing, swimming) and it can also affect human health (see below and Chapter 4 on biodiversity). Eutrophicating pollution originates from point sources (urban wastewater systems) and diffuse sources (mainly runoff from agricultural land). Each issue is discussed below.