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• Based on P8 modeling from 2008 and 2009 combined, 3,413 pounds of TP was discharged, along with 5,587 acre feet of runoff. This corresponds to a predicted yield of .61 pounds of TP per acre foot and a concentration of .22 milligrams per liter. • Based on P8 modeling, 3,413 pounds of phosphorus would typically be generated over a two year period, an average of 1,706 pounds would be generated annually. This corresponds to a total phosphorus yield of .0835 pounds per acre of land per year. • P8 results indicated .4 pounds per acre per year would be generated from Hardwood Creek and .51 pounds per acre per year would be generated from Clearwater Creek. This modeling estimated concentrations of total phosphorus in stormwater from Clearwater Creek at 360 micrograms per liter and Hardwood Creek at 400 micrograms per liter. • P8 modeling indicated unit runoff volumes at 4 inchers per year for Hardwood Creek and 6.6 inches for Clearwater Creek. Findings from P8 Modeling and GIS Analysis of City Data: • The City of Hugo has 9,076 of land tributary to Clearwater Creek. • The City of Hugo has 11,360 of land tributary to Hardwood Creek. • In 2005, the City of Hugo had 2,285 acres of impervious surface in Clearwater Creek and 1,401 acres of impervious surface in Hardwood Creek. • Between 2005 and 2030 the City of Hugo anticipates increasing the amount of impervious surface within Clearwater Creek by 3,180 acres and within Hardwood Creek by 1,201 acres. • P8 modeling predicts that between 2005 and 2030 with no BMPs in place, the volume of runoff will increase by 6,948 acre feet per year, based on a 3,180 acre increase in impervious surface. This represents an increase of approximately 2 feet of runoff volume annually for each acre of impervious surface added. • P8 model predicts 6,641 pounds of additional phosphorus will be generated by development with no BMPs and reflects the increase in 3,180 acres of impervious surface. This represents an increase in phosphorus loading by approximately 2 pounds per acre of impervious surface added. • P8 modeling estimates the concentration of phosphorus in untreated stormwater will be between 350 and 400 parts per billion. This corresponds to approximately 1 pound of phosphorus in each acre foot of additional runoff volume. CIP for Storm Water Projects Within the City of Hugo City of Hugo, MN WSB Project No. 1687-85 Page 17