The Coon Creek water yield augmentation pilot project

The Coon Creek pilot project represents an attempt to verify that water yield augmentation technology, demonstrated to work on small-scale experimental watersheds, could be applied at an operational or landscape scale with similar results. Coon Creek, a 1673 ha (4133 a) catchment on the East Fork of the Encampment River was selected as the treatment watershed and Upper East Fork, an adjacent catchment, was selected as the control. Following an adequate calibration period, road building and timber harvest disturbed a total of 23.7 percent of the watershed area. Seasonal streamflow (April-October) significantly increased an average of 71 mm (2.8 in) for the first 3 years after harvest. Peak flows, expressed as either instantaneous maximum flow or as maximum mean daily flow, were not significantly increased although the duration of the higher, near bankful, discharges were extended. The findings at Coon Creek support and are comparable with documented observations on smaller experimental watershed studies in the snow zone.