Journal of Student Research 2018

79 Urban Photsphorus Runoff and Loading to Half Moon Lake, Wisconsin Data Analysis Microsoft Excel® was used to determine mean event flow, mean daily flow, total P, and SRP. Mean event concentration (mg/m3) was multiplied by the corresponding mean event flow (m3/s) to estimate P loading (mg or g/s or event). Microsoft Excel® was also used to perform statistical regression analysis between precipitation and flow, total P, and SRP. Results and Discussion Between May and September of 2017, ~25 storm events were captured for P concentration determination from storm sewer two (Fig. 6) <

Figure 6. Seasonal variations in daily precipitation (upper panel), flow, and phosphorus ((P) concentration (lower panel) during the summer of 2017.

Each storm event contributed higher concentrations of total P and lower concentrations of SRP into Half Moon Lake, resulting in a summer flow-weighted mean total P and SRP concentration of 0.112 mg/L and 0.009 mg/L, respectively. Mean summer precipitation was low in 1999 compared to the long term mean (Fig. 7)