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I I I I I I I I I I I I I I I I I I TABLE 2 Frequency of Annual Peaks, by Month, and Related Average Peak Flow Fraser River Vasquez Creek Sta. No. 09024000 Sta. No. 09025000 No. of Annual No. of Annual Month Peak Flows AvF,. Qp Month Peak Flows AvF,. Qp April 1 35 April 4 35 May 10 179 May 7 310 June 46 288 June 29 353 July 3 114 July 3 354 October 1 54 Sept. 1 79 November 2 53 Nov. 2 172 Period of Record b3 years Period of Record 4b years The high number of annual peaks in the month of June and the magnitude of these peaks, compared to other months, suggest that most annual floods have a significant snowmelt contribution. According to U.S.G.S ("Annual Snowmelt and Rainfall Peak-Flow Data," Elliott, J.G. Jarrett, R.D. and Ebling, J.L.) snowmelt peaks at stations above 6,000 to 7,000 ft. generally occur in May to June. Thirteen strip charts (Tables 3 and 4) were obtained from the U.S.G.S. archives. For the Fraser station, records prior to 1938 were handwritten notes only and not useful for snowmelt analysis. Both the Vasquez and Fraser stations were digitized in 1973 and therefore stream hydrograph records are not readily available. Records of the highest peak flows between 1938 and 1973 were examined (Figures 5 to 9). One lower peak flow was selected for analysis (Fraser, 1938). Scrutiny of these strip charts shows that most of the annual peaks demonstrate characteristics of snowmelt-controlled runoff. These characteristics include a diurnal pattern for several days before and after the peak and a wide-based hydrograph with a flat peak. Only two of the records examined (June, 1938 - Fraser and May, 1956 - Vasquez) have. a high narrow peak representative of a thunders torm runoff event. One of these (May. 1956 - Vasquez) -3-