Dam Performance along Left Hand Creek during the Front Range Flood of 2013

Severe flooding on the Front Range of Colorado in September 2013 tested many dams, including several dams on and adjacent to the Left Hand Creek drainage north of Boulder, Colorado. A tropical-like storm drove moisture up against the foothills, dropping 200 mm (8 in) to more than 350 mm (14 in) of precipitation in a 24-hour period based on a number of weather stations within the watershed. The precipitation resulted in flash flooding in Left Hand Creek. A dam west of the main precipitation event experienced no damage. A diversion dam near the mouth of Left Hand Canyon was completely destroyed by the storm event due to scour. An off-channel valley reservoir dam experienced damage to both the service and emergency spillways. The experiences along Left Hand Creek demonstrate the need for geotechnical and structural design of dams for extreme events, especially in mountain environments where uncertain flood events can occur due to unusual weather patterns.