On July 24, 2004, about 1900 central daylight time, an Aerostar RX-7 balloon, N7144Y, piloted by a private pilot, experienced a hard landing during which the pilot suffered a broken leg. The personal flight was operating under 14 CFR Part 91 without a flight plan. Visual meteorological conditions prevailed. The pilot sustained serious injuries. The passenger reported no injuries. The local flight departed the Wausau area approximately 1850. In her written statement, the pilot reported a normal ascent from the launch field. She noted that the balloon was in level flight about 500 feet above ground level (agl) for the first 5 minutes of the flight. The pilot stated that the balloon then encountered turbulence. Initially the balloon climbed at 800 feet per minute (fpm) on a north-northwesterly heading. When it reached 1,800 feet agl the direction of the prevailing winds switched toward the southeast. Shortly afterward the balloon began to descend at 800 fpm. The pilot stated that when the balloon reached an altitude of 100 feet agl she attempted a normal landing. She estimated the wind was about 3 miles per hour toward the east-southeast. During the landing attempt, a wind gust lifted the balloon up and over some trees and across a road. She reported that the balloon subsequently landed normally in a "swampy" area. However, before she could alert the ground crew a wind gust lifted the balloon to about 250 feet agl. The balloon traveled across a road and dropped into a hay field. She reported that she broke her leg during the hard landing. The pilot noted that because the envelope was partially deflated at this point, she did not have time to use the airborne heater to soften the impact. The balloon was subsequently dragged by the wind until she could retrieve the vent line to fully deflate the envelope. The pilot stated that she had obtained a pre-flight weather briefing from Green Bay Automated Flight Service Station. She also reported that they had launched several PIBAL's (pilot balloon observation) to check upper level winds prior to launch.