A toxic plant, Water Hemlock prefers wetter locations and grows .5 to 1 meter in height. It has small clusters of white flowers in an umbrella formation. The plant may resemble common yarrow or cow parsnip that are also in the carrot/parsley family. Water Hemlock is inconspicuous in appearance but highly toxic. The toxin cicutoxin acts directly on the central nervous system and is a violent convulsant. Symptoms can appear in as little as 10 minutes. Primary methods for poisoning are ingestion, however skin contact may also cause a reaction. The attached pictures give an idea what the plant looks like.
The public is advised to keep away from this plant if discovered growing at the park and immediately contact a Poison Control Center if exposed.
In dealing with invasive plant species, Dallas Park and Recreation considers non-chemical control methods such as physical removal first as part of its Integrated Pest Management (IPM) program. However, because of the toxicity of Water Hemlock, hand pulling or mowing the plant presents a high level of risk to city employees and risk of inadvertent exposure to the public during the handling process. Therefore, in consideration of the best way to minimize exposure to both city employees and the public, the department is applying an herbicide to eradicate the plant. A licensed Texas Department of Agriculture pesticide applicator will treat areas where the plant is growing. The herbicide that will be used is Rodeo (a.i. glyphosate) and is approved for use near aquatic environments such as White Rock Lake.
After the initial treatment, the department will actively monitor the effectiveness and determine if additional treatments are needed.
If the initial treatment is effective, the plant will dry up and roots killed to neutralize any toxicity and threat to human health.
While the department 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. The application will be targeted specifically toward Water Hemlock and not to any surrounding vegetation.