On June 4, 1995, about 0945 Alaska daylight time, a wheel equipped Piper PA-18-160 airplane, N2400S, received substantial damage while attempting to takeoff from an off airport site near the Theodore River, located approximately 15 miles north of Tyonek, Alaska. The Alaska State Trooper commercial certificated pilot and the one passenger aboard were not injured. Visual meteorological conditions prevailed, and a company flight plan was filed. The purpose of the public use flight was for enforcement of the State of Alaska's Fish and Game Regulations. The pilot said he landed the airplane after he observed what he believed was illegal activity next to the Theodore River. He said after his enforcement action, he attempted to takeoff from the unimproved, wet and grass covered 1,200' long strip. A soft field takeoff was initiated, but the airplane did not become airborne prior to entering an area of deeper water and taller vegetation. The pilot said the airplane did not have sufficient flying speed, and he aborted the takeoff. During the ensuing period of deceleration, the airplane ground looped approximately one-quarter of a turn to the right and nosed down. The pilot indicated that he was not aware of any preimpact mechanical anomaly with the airplane.