White Rock Lake near former Dreyfuss Club site. Photo by Renee Umsted.

Water hemlock, a poisonous plant, has been found at multiple locations at White Rock Lake.

All parts of the plant are poisonous, and because it’s growing along the lakefront, where park visitors may accidentally come into contact with it, the Dallas Park and Recreation Department’s Maintenance and Operations team is working to eradicate the plant quickly, according to a memo from Director John Jenkins.

The park maintenance staff plans to apply an herbicide called Rodeo (glyphosate) to eradicate the water hemlock, as hand removal could be dangerous to City employees.

A TDA-licensed pesticide applicator will apply the Rodeo the morning of July 22, and park maintenance staff will monitor the area in coming weeks to make sure the treatment was effective; if it is, the plants will dry up, and the roots will die, eliminating the threat to humans. The treatment will be targeted toward water hemlock and not surrounding plants.

“While PMO has not used glyphosate products around the lake in years, the current situation represents a unique threat to public health and Rodeo is the most effective product that will kill the plant including the roots,” Jenkins writes in the memo.

Here are a few defining characteristics of water hemlock:

  • It prefers wetter environments and grows between half a meter to 1 meter in height.
  • Small clusters of white flowers grow on it in an umbrella shape.
  • It could resemble common yarrow or cow parsnip, which are in the carrot/parsley family.

Water hemlock’s poison can be ingested, but skin contact can also cause a reaction. It contains cicutoxin, which acts on the central nervous system and is a violent convulsant. Symptoms may occur within 10 minutes of exposure. If you are exposed, contact a Poison Control Center right away.