As lakes respond to increased input of nutrients such as phosphorus and nitrogen, there can be an increase in the number of algal blooms, causing reduced recreation and potential impacts to fish. In order to manage the input of nutrients, it is necessary to determine the loads coming into the reservoir (load = concentration x flow). Nutrient load determinations often include partitioning the loads into various sources, such as wastewater treatment plants, stormwater runoff, non-point runoff, and groundwater inputs.