On August 28, 2004, about 1730 Pacific daylight time, an experimental Quicksilver MXL II, N4358Z, collided with high vegetation and impacted terrain while flying at low altitude, 3 miles north of Rio Vista, California. The owner was operating the airplane under the provisions of 14 CFR Part 91. The pilot and passenger were not injured, and the airplane was substantially damaged. Visual meteorological conditions prevailed, and no flight plan had been filed. The local area personal flight originated at the Rio Vista airport about 1710. The pilot stated in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that he was flying northbound a few feet above an unused levee dirt road. The right wingtip struck a stand of high bamboo growing along the east side of the road. The airplane then hit the road, skidded off the road, and into some large rocks along the levee. Both occupants were able to extract themselves out of the wreckage.