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Flood potential also exists from the rapid melting of heavy snow cover in the late spring. Floodflows resulting from snowmelt are characterized by moderate peaks, large volume, and long duration. This type of flood is usually not as damaging as those resulting from general rainstorms. The potential flooding hazard at Bayfield is controlled by the discharge from the Vallecito Reservoir, 11 miles upstream of Bayfield. The maximum flood of record occurred in July 1957, when heavy rains in the mountains to the north filled the Vallecito Reservoir to its ultimate capacity. The three flood gates opened simultaneously, releasing a surge of water at approximately 13,000 cubic feet per second. The river stage at Bayfield reached the top of the u.s. Highway 160 bridge. The high water caused basement flooding and agricultural loss. Other major flooding in the Bayfield area occurred in October 1911 and July 1927. In 1911, the Los Pinos River inundated the land along the river at Bayfield for nearly a week. One house was washed away, while the water reached a depth of 3.5 to 4.0 feet at the fairgrounds. Residents reported that the 1927 flood stage was about equal to the 1911 flood. In September 1901, flooding was reported in the San Juan River basin; however, the Los Pinos River did not overflow its banks. 2.4 Flood Protection Measures No specific flood protection works have been undertaken in the Town of Bayfield. However, some flood protection measures are provided in the Town Ordinance and La plata County Flood Hazard Regulations for areas within the lOa-year flood plains. Ordinance No. 99 provides land use and control measures with effec- tive enforcement provisions consistent with the criteria set forth in Section 1910 of the National Flood Insurance Program Regulations. 3.0 ENGINEERING METHODS For flooding sources studied in detail in the community, standard hydro- logic and hydraulic study methods were used to determine the flood hazard data required for this study. Floods having recurrence intervals of 10, 50, 100, and 500 years have been selected as having special significance for flood plain management and for flood insurance premium rates. The analyses reported here reflect current conditions in the watershed of the flobding source. 3.1 Hydrologic Analyses Hydrologic analyses were carried out to establish the peak discharge- frequency relationships for floods of the selected recurrence inter- vals for the stream studied in detail in the community. 4