Pat Harrison Waterway District (PHWD) is a Mississippi State Agency with headquarters in Hattiesburg. The agency was created in 1962 with a directive of flood control in southeastern and east central Mississippi.

The Pascagoula River is a river, about 80 miles (130 km) long, in southeastern Mississippi in the United States. The river drains an area of about 8,800 square miles (23,000 km²) and flows into Mississippi Sound of the Gulf of Mexico. The Pascagoula River Basin is managed by the Pat Harrison Waterway District.