USGS Scientific Investigations Report 2009–5123Hydrology of the Johnson Creek Basin, Oregon

Table 4. Magnitude and probability of peak streamflow of Johnson Creek, Oregon.

[Map numbers are shown in table 1. Abbreviations: ft³/s, cubic foot per second; n, number of years]

Water years	Recurrence interval (years)	Annual exceedance probability (percent)	Peak streamflow (ft³/s)
Johnson Creek at Sycamore (map number 30) (systematic n = 66; historical n = 0; weighted skew = 0.448)
1941–2006	1.25	80	717
	2	50	1,150
	5	20	1,750
	10	10	2,140
	25	4	2,590
	50	2	2,920
	100	1	3,220
Johnson Creek at Sycamore (map number 30) (systematic n = 17; historical n = 0, weighted skew = 0.095)
1990–2006	1.25	80	693
	2	50	1,040
	5	20	1,580
	10	10	1,970
	25	4	2,510
	50	2	2,930
	100	1	3,380
Johnson Creek at Milwaukie (map number 41) (systematic n = 17; historical n = 0; weighted skew = 0.104)
1990–2006	1.25	80	840
	2	50	1,140
	5	20	1,570
	10	10	1,860
	25	4	2,240
	50	2	2,530
	100	1	2,820