On October 3, 1999, about 1510 Alaska daylight time, a wheel equipped Bellanca 7GCBC airplane, N4156Y, sustained substantial damage during takeoff from the Lake Hood Airstrip, Anchorage, Alaska. The airplane was being operated as a visual flight rules (VFR) personal flight under Title 14, CFR Part 91, when the accident occurred. The private pilot, and the one passenger aboard, were not injured. Visual meteorological conditions prevailed, and no flight plan was filed. During an on-scene interview with the National Transportation Safety Board (NTSB) investigator-in-charge on October 3, the pilot reported that he was departing on runway 31. He reported that as the airplane climbed to about 100 feet above the runway, and while approaching the departure end of the runway, all engine power was lost. He said that he made an emergency landing in a tundra-covered marsh, just off the end of the departure runway. During the landing roll, the airplane's main wheels contacted the soft, boggy terrain, and the airplane nosed over. The airplane sustained substantial damage to the wings, right lift-strut, and empennage. The airplane owner recovered the airplane from the accident site, and returned it to his parking tie-down area. On October 4, the IIC removed the engine carburetor, and found about 10cc of rusty-colored fluid, along with clean fuel in the airplane's carburetor float bowl. The rusty-colored fluid tested positive for water, when tested with water detection paste. At the request of the accident pilot, the fluid sample was returned to his possession. In a telephone conversation with the NTSB investigator-in-charge on December 3, the accident pilot stated that an independent testing facility detected therapeutic levels of fluoride within the fluid sample. He added that the level of fluoride found in the sample were consistent with that found within local area tap water. The pilot did not submit the test results report to the NTSB.