Water-Supply Paper 2499

U.S. Department of the Interior
U.S. Geological Survey

Summary of Floods of 1992

June 14-15, 1992, Along the North Fork Powder River Below Pass Creek, Near Mayoworth, Wyoming

By Jeff C. Vigil

Intense rain, associated with strong convection, fell over much of north-central Wyoming on the night of June 14 and morning of June 15, 1992, and caused flooding on the North Fork of the Powder River and other tributaries of the Powder River (Evans, 1993). The National Oceanic and Atmospheric Administration (1992) reported 4.06 inches of rain at Buffalo and 5.60 inches, 15 miles south of Buffalo, on June 14th and 15th. Unofficial reports indicated that more than 6 inches of rain fell southwest of Buffalo (fig. 38). Most of the rainfall occurred in an 18-hour period and was equivalent to a 24-hour design storm having a recurrence interval of 100 years (Evans, 1993).

The streamflow-gaging station on North Fork Powder River below Pass Creek, near Mayoworth, Wyoming (site 1, fig. 38), had a maximum stage of 7.47 feet and a maximum discharge of 1,090 cubic feet per second on June 15. This discharge has a recurrence interval of about 20 years, but it did not exceed the 1984 maximum discharge of 1,590 cubic feet per second (table 21). At a bridge about 7 miles downstream from site 1, floodwaters overtopped the road embankment.

Stream stages in the affected drainage areas increased downstream from the area of greatest rainfall. Wyoming State Engineer Office personnel reported an increase in stage of more than 7 feet at the streamflow-gaging station on Crazy Woman Creek at Trabing Bridge (site 2, fig. 38) (Carmine LoGuidice, Wyoming State Engineer's Office, written commun., 1993).

Johnson County Road and Bridge Department officials (oral commun., 1993) reported minor damage to roads and bridges in Johnson County. The greatest damage occurred to road surfaces and shoulders of roads as a result of overflowing water, and some roads were closed for as long as a week. Rip-rap structures around bridges and culverts also were reported to have been damaged. The area affected is sparsely populated, so that monetary damage resulting from this flood was small.

Reference

Evans, J.S., 1993, Flash flooding in central Johnson County, Wyoming: National Weather Service Central Region Technical Attachment 93-19, 7 p.

National Oceanic and Atmospheric Administration, 1992, Climatological data, Wyoming, June 1992: U.S. Department of Commerce, v. 101, no. 6, 27 p.