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In general, nonpoint source(NPS) is composed of traffic pollutants, sediments adsorbed pesticides and nutrients. It is discharged from irrigation containing microorganisms, dissolved nutrients and excess waste of crops. It is known that the management of NPS is more difficult than that of point sources due to intermittent occurrence, dispersion of discharge area, diversity types and loads of sources. This research focuses on the estimation of NPS loads to the rainfall in the Jungrang stream area for the year of 2001, especially, within the initial period of stormwater. And also NPS loads were calculated based on analysing pollutants and discharge during the period of rainfall. The investigation was performed for the effects on the value of the units of NPS loads by the rainfall, intensity and preceding dry days. As the results, peak values of BOD, COD and SS were about 502 mg/L, 179∼904 mg/L and 326∼756 mg/L, respectively. However, those of the normal influent concentration to the third treatment system in the Jungrang STP were in the range of 85∼140 mg/L, 39∼73 mg/L, 54∼113 mg/L, respectively. The units of NPS loads were calculated as follows; BOD 372, COD 713, SS 719, T-N 86 and T-P 23 kg/ha/yr, respectively. These results were in the previous researches on the calculation of unit NPS loads. The influenced factors to the unit of NPS loads were the rainfall intensity, the preceding dry days and the mean rainfall intensity in the order. According to the result from the regression analysis, R2 for the accumulated amount of rainfall was revealed the highest value as 0.97.키워드(Key Words): 비점오염원(nonpoint source(NPS)), 초기강우기간(initial period of stormwater), 비점오염원단위(unit of NPS loads), 선행무강우일수(preceding dry days), 평균강우강도(mean rainfall intensity)