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DRAFT Field Report Saguache County Flood of .Jul:V 26, 1999 Saguache Creek and Tributaries Background and Storm Event On July 26, 1999 a rare and severe storm dumped heavy rainfall on portions of northern Saguache County, located within the Rio Grande drainage basin in south central Colorado. A storm total precipitation of 7.5" of rain in less than 90 minutes was reported by one landowner. The storm appeared to be centered approximately 10 to 15 miles northwest of the town of Saguache, north of State Highway 114. Saguache Creek and se:veral tributary streams collected significant runoff from the storm event. Saguache County is in an area known as the San Luis Valley, a high elevation valley surrounded by the San Juan Mountains/Cochetopa Hills to the west, the Sangre De Cristo Mountains to the east, and the Sawatch Range to the north. The town of Saguac:he is the County Seat and has a population of 676 (Dept. of Local Affairs, 1997), while the entire county has a population of 5,911 (Dept. of Local Affairs, 1997). The economic base for the county consists mainly of agriculture, ranching, tourism, and some retail sales in the population centers. Hydrologic and Hydraulic Information . The Saguache Creek drainage has its headwaters at the Contiliental Divide with elevations in excess of 14,000 feet. Middle Creek and Jacks Creek, two tributaries to Saguache Creek that were studied for this report, also have their headwaters at the Continental Divide with elevations in excess of 13,000 feet. The flood producing rainfall for this event fell at ground elevations between 8,000 feet and about 10,000 feet. Saguache Creek is a perennial stream that drains an area of 595 square miles at the gaging station (located approximately 8 miles upstream of the town of Saguache). The normal base flow in Saguache Creek in late summer is in the range of 100 cfs. The only known precipitation measurement within the storm area was collected by a landowner having a cylindrical (non-tapered) metal rain gage (homemade gage). The landowner specifically uses the device to measure rainfall. The reported storm total amount from this gage was 7.5" in about 90 minutes. The landowner was interviewed by the Saguache County Emergency Manager (Larry Zimmer) immediately following the event, but was not interviewed by CWCB staff at the time of the field visit. The elevation of the rain gage is approximately 8,200 feet. . . CWCB staff performed field investigations on August' 5, 1999 to document flooding characteristics and damages in the affected watersheds. Stream cross-sections, high watt:r marks, and slopes were measured with standard survey equipment. Photographs and notes were also taken to document the event. . ;