U.S. Geological Survey

National Water-Quality Assessment Program

Fiscal Year 1991 Study Units

This group of study units started in fiscal year 1991:

• Apalachicola-Chattahoochee-Flint (#22 on map)
• Albemarle-Pamlico Drainage (#19)
• Central Columbia Plateau (#50)
• Central Nebraska Basins (#35)
• Connecticut, Housatonic, Thames River Basins (#2)
• Georgia-Florida Coastal Plain (#23)
• Hudson River Basin (#3)
• Lower Susquehanna River Basin (#6)
• Nevada Basin and Range (#55)
• Ozark Plateaus (#31)
• Potomac River Basin (#8)
• Red River of the North (#18)
• Rio Grande Valley (#45)
• San Joaquin-Tulare Basins (#56)
• South Platte Basin (#40)
• Trinity River Basin (#33)
• Upper Snake River Basin (#48)
• Western Lake Michigan Drainage (#16)
• White River Basin (#13)
• Willamette River Basin (#53)