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, Lawn Lake. OC-39 July 15, 1982 Payu e 2. At 4:00 P. M., I contac:eu Man Pearson, Ch icf of the Dam Safety [Jranch. At that time, I indicated that the dam had llQl filLled due to overtopping. Our current suspeeions weru rhilt il seepilgu [ililuf(" hilu occurreu with pipiny initiilteu by a pervious seam in the dam, progressive sloughing of the dam slope, or failure of the outlet conduit. 3. At 5:30 P.M., I met with Bob Jarrett, hydrologist for the U.S. Geological Survey, Bob's telephone number is 234-3487. Bob had tentatively selected two sltes for indirect measurement. The first site is lccated approximately 1/2 mile upstream from Cascade Lake and the second located about 1 1/2 miles upstream from Estes Park. A discussion with Eric Wilkinson and Mr. Jarrelt: Apparently, The Bureau of Reclamationtook periodic readings at approximately 5 minute intervals on the surface water elevation at Lake Estes. By use of this information and the area capacity curve of that lake, an inflow hydrograph could be recreated at the point the Big Thompson enters the lake. 4. I spoke to Mr. L. V. Davis, operator of the Cascade Cottages. Mr. Davis's phone number is 586-4748. His address is Cascade Cottages, Estes Park, Colorado 80517. Mr. Davis sa id that the dam at Cascade Lake belonged to the City of Estes Park and was used in power generation. His eye-witness account was that the dam withstood 6 feet of overtoPPin~rior to fa Llure. Cas- cade Lake was formed by a concrete gravity dam. 5, According to measurements taken by [rie W,lkll1son, Cascade Dam hau a vertical height of 12 feet at the left portion of the dam, 14 feet at the outlet gate, and 15 feet at the power plant intake structure. The flood highwater marks were about 5 feet above the lake's normal hlghwater line. Highwater marks were flagged on the south side of Fall Hiver Channel by Rogers and Wilkinson, This was accomplished between Horseshoe Park and downstream to a point 100 yards below Cascade Dam. The north side of the channel was flagged for high water marks by Jarrett, the evening of July 15,1982. 6. I spoke to Bill Farrar. Mr. Farrar was a guest at the Cascade Cottages at the time the dam falled. His phone number's (512) 492-2333. His address is 14303 Shumard Oak Woods, San Antonio, 'IX 78249. Mr. Farrar said that he obtained photographs prior to, during, and after the failure of Cascade Dam. I provided him with my card and he said he would forward copies of these photographs to us for our use. They indicated that the dam had fa iled approximately 7:50 A.M. He said that trash began stacking up on the dam as the structure began to sustain significant overtopping. The outlet control house bsgan to break away and then he noticed the right abutment of the dam begin to rotate in a downstream direction. Following this, the entire structure began to lean forward at the right abutment and finally toppled over hinging around the left abutment contact.