Montgomery Parks Reports Elevated Levels of Microcystin at Lake Needwood and Lake Frank; Visitors Asked to Use Caution

August 1, 2016

Pet owners urged to keep dogs out of the lake; boating and fishing remain open.

SILVER SPRING, MDMontgomery Parks, part of the Maryland-National Capital Park and Planning Commission is asking residents to use caution when recreating on or near Lake Needwood and Lake Frank located within Rock Creek Regional Park. Testing has shown there are elevated levels of microcystin, a toxic substance produced by some species of blue-green algae (cyanobacteria), in both lakes. Microcystin, a hepatotoxin, can cause harm to the liver of humans and pets if ingested. Of particular concern are dogs that are off-leash and may swim and/or drink from the lake, despite park regulations. Montgomery Parks urges visitors to take the following precautions:


  • Park visitors are encouraged to avoid direct contact with water while boating or fishing
  • Notice that swimming is prohibited in the lake at all times
  • Keep dogs on leash (as is regularly required at the park), and do not allow them to drink or be in contact with the water
  • Wash hands thoroughly prior to eating, drinking, or smoking if someone comes in contact with the water
  • Only eat properly cooked muscle meat of fish that are caught in the lake


Recreational activities including boating and fishing will remain open at the lake.


Signs have been posted around Lake Needwood and Lake Frank indicating that elevated levels of microcystin have been found, and to urge visitors to take precautions. Portions of both lakes may be contaminated for the rest of the season. Montgomery Parks will continue to monitor the lakes and update signs when the warning is lifted.


For updates or more information, visit



About The Maryland-National Capital Park and Planning Commission Montgomery Parks:


Montgomery Parks manages more than 36,000 acres of parkland, consisting of 418 parks. Montgomery Parks is a department of the Maryland-National Capital Park and Planning Commission (M-NCPPC), a bi-county agency established in 1927 to steward public land. The M-NCPPC has been nationally recognized for its high-quality parks and recreation services, and is regarded as a national model by other parks systems.


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