The pilot reported that he did not observe any obstacles when he overflew the lake, but noted there was some bird activity in the vicinity. He performed a low altitude pass, approximately 100 feet above the lake, without incident. During a second low altitude pass, the pilot heard a "thump" noise which was immediately followed by a loss of engine power and engine vibration. A forced landing was made in a nearby muddy field, but the airplane nosed over shortly after touchdown. The airplane impacted a static wire that was strung across the lake. The wire, approximately 40 feet above the water, was part of two-wire power transmission line. The airplane's propeller had damage consistent with a wire strike.