Trial Lake Dam - Hydrology, EAP, SOP and Inundation Map Experience

Trial Lake Dam is located in the High Uinta Mountains in Central Utah at an elevation of about 10,000 feet. The dam is 40 feet high and stores I,700 acre-feet of water for downstream uses. Originally constructed in 1-910, the dam failed during the first filling. The dam was raised and a saddle dike added in 1925. On June 7, 1986, the saddle dike failed during reservoir filling. The reservoir has remained empty until recent construction. The preliminary design was completed in 1988 and the final design in 1990. Alternative embankment sections were considered for rebuilding the existing dam and dike, one of which was using the existing dam for a central core. Examination of the existing dam embankment showed it to contain loose fill and voids and that it did not have a filter between the core and downstream rock fill; thus, removal of the existing dam and dike was required, The design of the new dam, dike, and hydraulic structures was completed in the spring of 1990 and construction began in June 1990. Because of funding constraints, weather conditions, and irrigation demands, construction had to be completed in one construction season from June 1990 to October 1990. Furthermore, because the dam is located in an environmentally sensitive area, close coordination with federal and state agencies was required. The cooperative effort of these agencies was instrumental in completing the project on schedule.