Tri-County Lakes Administrative Commission

Non-Native Species of Concern

What are Non-Native Species of Concern? 

The Environmental Committee reviews articles about invasive species that could potentially be harmful to the ecosystem of Smith Mountain and Leesville lakes. Those species that have entered other Virginia waterways are of particular concern. The committee also watches those species in neighboring states to track their migration and take measures to prevent their introduction to our lakes.

If you identify one of these species in a local body of water, please contact TLAC at 540-721-4400.


Non-Native Aquatic Vegetation of Concern – not identified in Smith Mountain Lake

Two-horned Trapa – Trapa Bispinosa


Two-horned trapa (water chestnut) invades freshwater habitats such as ponds, lakes, and slow-moving streams.  It has the potential to obstruct water flow, inhibit recreational and commercial use of waterways, shade out submerged aquatic vegetation, starve aquatic species of oxygen, and outcompete native aquatic plants. A water chestnut colony can smother an entire pond or lake.

Plant Description

Leaves:  Two-horned trapa has floating leaves that are green with red undersides. Each leaf has an “inflated” petiole that allows the plant to float. Due to cold temperatures, two-horned trapa dies back in late autumn, but seeds can lie dormant for at least two years.

Flowers:  Small, pink flowers with four petals emerge from the rosette center beginning in June. Two-horned trapa may flower and fruit from June until frost.

Reproduction:  Seed production. The seed pod is up to 2 inches, with two opposing “horns.” These seed pods are classic aquatic hitchhikers. The horns attach to waterfowl and disperse into neighboring waters during the birds’ travels. Two-horned seed pods can lie dormant for at least two years.


Some historic observations recorded before 2014 thought to be Euroasian water chestnut have since been reclassified as two-horned trapa. Stafford and Westmoreland counties have records from 1995 retroactively identified as two-horned trapa, but those counties have not been monitored to determine if those colonies persist today. Two-horned trapa has not been found outside of Virginia, and management efforts are underway at many sites.

As of late 2021, two-horned trapa is known to occur at over 70 locations in northern Virginia, including the counties of Fairfax, Fauquier, Prince William, and most recently, Loudoun County.

It was identified in a pond in Charlotte county in 2022. It is possible that boating or construction transit was responsible for the spread across the state.

Without action, two-horned trapa will continue to spread. Implementing rapid response measures is essential to slowing the spread and future eradication.


More information about Two-horned Trapa:
Virginia Department of Wildlife Resources

Two-horned Trapa (