On August 18, 1994, at 1830 Alaska daylight time, a float equipped DeHavilland DHC-2 (Beaver) airplane, N1785R, owned by the Chelatna Lake Lodge, and operated by Willow Air Service dba. Northern Alps Inc., collided with a tree stump while taxiing for takeoff on the Yetna River at the mouth of Lake Creek. The commercial certificated pilot-in-command and his one passenger, the sole occupants, were not injured and the airplane sustained substantial damage. The non-scheduled 14 CFR Part 135 fishing/guide flight last departed Willow, Alaska at 1700 and the intended destination was the area in which the mishap occurred. The pilot reported that visual meteorological conditions prevailed in the area in which the accident occurred and a company flight plan was in effect. The pilot reported that while powering up to taxi off of a sandbar the right horizontal stabilizer collided with a tree stump. According to the pilot/operator report submitted by the pilot, his total aeronautical experience consists of about 1,700 hours, of which 200 were accrued in the accident aircraft make and model. In the preceding 90 and 30 days prior to the accident, the report lists a total of 200 and 65 hours respectively flown.