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OCT-30-96 WED 14:02 BRR BLD 53 DFe FAX NO, 2365034 p, 06 I I: 11 AUgluat 18. 1DgO Storm n..r OD.'J Wvoml"SI wU 'fetor On September 24( Don Jensen iIIld I visited the Opal, Wyoming area to estimate peak discharges and spallal distribution of the 1990 storm runoff (rainfall bucket.su~data suggest 7 inches in about an hour). Opa/Is located lIbout 11 miles eut of Kemme~ eouthwestern Wyoming and 6 miles weat of the Sears' ranch where the mulmum rainfall was r&por1ed. Tributaries to the Hams Fork were reported al flooded during the 1990 storm. The eleval/on ranges from about 8,500 feet In the Hams Fork to about 8,870 feet at the head of Cow Hollow Creek, which Is the basin Immediately to the east of the Seare' ranch. During a visit to Opal on August 15, 1996, I Interviewed Mr. Bill Sears about the storm and estimated paleoflood discharges for several streams subject to the 1990 atorm, Mr. Sea,. indicated he recalled the 1990 storm very well. However, I noted several important inconslstencl.. with his version as discussed in the Corrigan and Vogel paper 'Meteorology of a Iocalllash flood near Opal, Wyoming 16 August 1lIgo." Most disconcerting was a lack of IloocI evidence In the Hams Fork, which he described as flooded from valley wall to valley wall (-0.5 mile. wide at hie ranch). Had .uch flood depthl occurred there would belubstantlal erOSional and deposition evidence olllooding, On our drive to Opal, I started 10 discuss what Mr. Sears told me with Don Jensen, but Don indicated that the version Mr. Sears gave him (and another version to one of Don's graduate students) differed from the version provicleclto CorriganNoge' .s well as what Mr. Sears told me. I suggested to Don that we should not discuss our "versions" further, but to documented in writing what Mr. Sears had told UI individually. Then, the different versiona of the storm description could be Independently evaluated, perhaps by another hydrometllorologlst, and inconsistencies resolved with a followup discussion with Mr. Sears (and/or others). For the Augu5t 1 DDO storm, the wor5t noodlng was reported In Cow Hollow Creek, which Is located about 1 mile east of Mr. Sears' ranch. The creek was descnbed as being backed up (ponded) upstream from Highway 30 for a distance of about half a mile. Water also was described .. flowing ovar the hIghway to a depth of about1B inches, thus, temporarily closing the road 10 through traffIC. A metal fence illocated on the upstream side of the Highway 30 culvert (10ft x 8 fl) to prevent cattle from going through the culvert. There is no debris on the fence now, but other fences at highway 30 culverts within the storm area have substantial debris from the 1990 flood. Good mud lines occur through the length of the culvert indicate a maximum 1990 flow depth of about 3 feel. Therefore. we concluded that the culvert was 5