Journal of Student Research 2018

72 Journal Student Research naturally in rivers, coastal waters, and lakes over geologic time (Wetzel 2001, Chislock et al. 2013), human activity and resultant changes in watershed land use have contributed to rapid cultural eutrophication and ecological deterioration of waterways (Aulenbach et al. 2017). Because freshwater algal productivity is usually limited by P availability, anthropogenic P loading and ensuing eutrophication can lead to high algal biomass, shifts to cyanobacteria dominance, bottom water anoxia, decreased Secchi transparency, loss of macrophyte diversity, and decline in desirable fish species (Søndergaard et al. 2003). In addition to habitat degradation, cyanobacteria can produce microcystins that pose a human health risk (Backer & McGillicuddy 2006). Thus, eutrophication is a tremendous problem being amplified by human activity and needs to be reversed by reducing P inputs to freshwater systems (Carpenter, 2008). Although soil management and fertilization in agricultural landscapes can be a major source of watershed P, urban areas are also major P contributors (Brezonik & Stadelmann 2002). Urban P runoff per unit area (i.e, kg/hectare) can be nearly as high as P export from agricultural row crop settings (Lin 2004). In urban settings, P loads to lakes usually come from impervious surfaces such as rooftops, sidewalks, parking lots, and streets. Because these urban features rapidly deflect water to storm drains rather than promoting infiltration of pollutants, P loading can be very rapid and amplified during precipitation events as most of the rainfall over a catchment area and phosphorus associated with debris, soils, dust, and litter on impervious surfaces can be flushed directly to a lake. Impervious surfaces allow storm water to run off the landscape picking up various pollutants before making its way to the nearest body of water without any treatment (Moore, 2015). In addition, developing urban areas may also contain a lot of construction sites. These areas can be a large contributing source of P runoff in urban settings (Brezonik & Stadelmann 2002). Best management practices (BMPs) can be implemented to reduce urban P loading. Lake rehabilitation can be achieved if external P sources are reduced (Cooke et al. 2005; Jeppesen et al. 2005; Sondergaard et al. 2007). Traditionally, decreasing peak runoff rate, and creating a detention pond to prevent flooding have been traditional methods to manage storm water runoff (Moore, 2015). BMPs can include structural design like a detention pond, or nonstructural design like stream buffers or changes in construction codes (Aulenbach et al. 2017). When BMPs are implemented water quality improvements can be observed. For example, Aulenbach et al. (2017) noted that an increase in BMPs, especially detention ponds, attributed to a decrease in total P concentrations.