WSSC Water Issues Recreational Water Contact Health Advisory for Triadelphia Reservoir

Laurel, Md. – July 18, 2023 – WSSC Water has detected high concentrations of blue-green algae, known as Harmful Algal Blooms (HAB), in the Triadelphia Reservoir. These HABS can cause adverse health effects. The reservoir, located along the Patuxent River in Montgomery and Howard counties, serves as a drinking water source for WSSC Water and a recreational area for hiking, fishing and boating. 

The health advisory does not affect the T. Howard Duckett Reservoir. 

WSSC Water’s drinking water is not affected and continues to meet all Safe Drinking Water Act standards. As a precaution, WSSC Water is closely monitoring water quality conditions at its Patuxent Water Filtration Plant. 

Visitors to WSSC Water’s Triadelphia Reservoir should do the following: 

• Avoid all recreational water contact. If water contact occurs, rinse off immediately with clean water. 
• Do not allow pets to swim in or drink the water (prohibited at all times by WSSC Water watershed regulations). 
• Do not consume fish livers or digestive organs from fish caught in the reservoir. If you catch a fish in the reservoir, wash the fillets thoroughly with drinking water. 
• Signs will be posted throughout the reservoir’s recreational areas to inform visitors of this water contact health advisory. 

Triadelphia Reservoir's water level is low due to an ongoing sediment removal project. All boat ramps remain closed, and boating is prohibited. Big Branch and Triadelphia Recreation Areas are open during the project, while Pig Tail and Green Bridge are closed. Shoreline fishing is permitted, but only in designated areas.  

If you, your pet, or someone you know has come in contact with or ingested water at the reservoir, call your local health department: 

• Montgomery County: 240-777-0311 (Montgomery County 311) 
• Prince George’s County: 301-883-4748 (Prince George’s County 311) 
• Howard County: 410-313-1773 (Community Hygiene Department) 

Water quality monitoring is occurring weekly. When the concentration levels decrease below the advisory thresholds, an alert will be posted at wsscwater.com. 

For more information on algal blooms, visit WSSC Water’s Algal Blooms page.