1992

• President Bush declares this year as the "Year of Clean Water."
• The Chesapeake Bay Program sets nutrient reduction goals for the Potomac and other bay tributaries.

1993

• An oil pipeline ruptures and spills over 400,000 gallons of diesel fuel into Sugarland Run, a Northern Virginia tributary of the Potomac.
• The American Rivers Association designates the Anacostia River as the fourth most endangered river in North America.

1996

• Total suspended solids in the Potomac River remain a problem, due to the increased development and higher runoff from impervious surfaces.
• Application of lawn and crop fertilizers contributes to higher than acceptable levels of nitrogen and phosphorus in the Potomac.

1998

• Maryland passes a Water Quality Improvement Act to address the problem of nutrient pollution. The Federal Clean Water Action Plan is initiated, emphasizing a watershed approach to restoring the nation's waters.
• The Potomac River is selected as an American Heritage River.
• Outbreaks of a fish disease traced to the Pfisteria microbe kill thousands of fish in the Chesapeake Bay and its tributaries.

2000

• The Commonwealth of Virginia plans to sue the State of Maryland over its right to draw drinking water from the Potomac River, which runs between the two states.
• The cause of a large fish kill in Rock Creek in Washington, D.C. is traced to a storm drain near an exterminator's offices in a Maryland suburb.

2005

• The Annual Potomac River Watershed Cleanup has expanded to include the entire Potomac watershed with 5,450 volunteers participating at 296 sites in 2005.