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Green Scum on Water Surface of Lakes or Ponds
At certain times of year, a bright green scum can occur on the water surfaces at Lake Needwood and Lake Frank. This is the result of a very dense 'bloom' of single-celled plants called algae. This particular algae thrives in hot, dry weather and in waters which have high amounts of nutrients (i.e. fertilizers). When these conditions occur, Montgomery County Parks may post bright yellow warning signs for visitors to these recreational areas. Residents should not drink or touch the water, nor swim or wade in areas where this bright blue-green bloom is evident, and should keep children and pets out of these areas. If contact is made, wash off with plenty of fresh water.

A fact sheet on this type of algae can be found on the Department of Natural Resources website by clicking on the link below. To find out the status of the bloom and the Parks recreational facilities, contact Parks at 301-495-2595.

Find more information from the following link(s):
  • Harmful Algae Blooms


  • To speak with a Customer Service Representative, please call 311 during business hours.