On July 6, 1994, about 0929 central daylight time, an Aerospatiale AS350, N901BA, registered to Bulldog Airlines Inc., leased to the United States Department of Interior for use by the United States Forrest Service, Region Eight, on a public-use ferry flight, encountered inadvertent instrument conditions, and crashed in the water in a borrow pit in the vicinity of Caryville, Florida. The helicopter sustained substantial damage. The airline transport pilot was not injured. Instrument meteorological conditions prevailed and no flight plan was filed. The flight originated from Tallahassee, Florida, about 47 minutes before the accident. The pilot stated he obtained a weather briefing from the FAA flight service station. He was informed the Alberto depression had stalled out, no advisory of "VFR flight not recommended" was given, but it was obvious instrument meteorological conditions prevailed. He departed Tallahassee, Florida, in marginal VFR flight conditions flying westbound over Interstate 10. The ceiling was ragged estimated between 500 to 600 feet, visibility between 3/4 to 1 1/2 miles with light rain. He observed towers about 3/4 of a mile in front of his flight path. He reduced his airspeed, turned to the right to go around the towers, encountered heavy rain, and visibility dropped to about 1/2 to 1/4 mile. The turn was continued towards a borrow pit that he had previously over flown when he encountered instrument flight conditions. He started a descent to 200 feet agl, regained visual conditions, saw the borrow pit and continued his descent with a fast closure rate. He made a deceleration described similar to a quick stop. The tailrotor collided with the water, the helicopter pitched forward, the main rotor blade collided with the water, and the helicopter rolled over on its right side. He exited the helicopter through the passenger door and swam to shore. The pilot concluded his judgement and situational response was impaired from fatigue due to lack of sleep. He further stated he should have waited for the weather to clear or should have flown further south along the shore.