Record Effort Ramps Up To Stop Exotic Invaders Threatening Texas Waters

Tom Harvey, 512-389-4453,

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Legislature Dedicates $6.3 million to Stop Aquatic Invasive Species

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AUSTIN – They blanket waterways and block boating, fishing and swimming, crowd out native species, spoil rivers and lakes, and clog power plant and municipal water pipes. They don’t belong here, yet more are coming all the time, spreading like a plague across the state. The good news: record funding approved by the Texas Legislature is launching new fronts in the war on aquatic invasive species.

This year and next, the Texas Parks and Wildlife Department is ramping up an unprecedented effort to control and stop the spread of aquatic invasive plants and creatures, attacking a seemingly ever-increasing hydra of threats, from giant salvinia and zebra mussels covering Texas lakes, to giant reed and saltcedar smothering rivers and streams, to exotic fish that compete with Texas natives and alter natural ecosystems. Other exotic invaders are aggressively spreading throughout nearby states and are knocking on the door of Texas. For example, exotic silver carp have wreaked havoc in the Midwest where boat propellers compel the fish to jump several feet from the water, and boaters and water skiers in parts of the Mississippi and Illinois rivers have been seriously injured by jumping carp. Bighead carp (another invader that competes with native fishes) and silver/bighead hybrids are just entering Texas in parts of the Red River and a few other locations, primarily in northeast Texas.

“It’s a huge challenge to address these problems all across our state, and no one organization can do it alone—the scale of the problem is just staggering,” said Tim Birdsong, who leads aquatic resource conservation programs in TPWD’s Inland Fisheries Division. “We have had the knowledge and tools to attack the problem—now we have increased resources to expand control efforts and conduct research to fine-tune solutions. This will also make possible enhanced education and information-sharing, as we urgently need the help of boaters, riverside landowners, river authorities, water management districts and other partners to be successful.”

Annual economic impacts of aquatic invasive species are estimated at more than $140 billion nationally, and globally the impacts are believed to be more than $4 trillion. In Texas, the impacts are far-reaching, costing the state billions of dollars annually, including threatening to undermine a recreational freshwater fishing industry worth more than $4 billion.

The most troublesome aquatic invasive species include giant salvinia, water hyacinth, saltcedar, giant reed, and zebra mussels. Water hyacinth has been documented to consume as much as 13 times more water than native aquatic plants, contributing to water supply losses in a chronically drought-stricken state. Also, dense mats of floating aquatic invasive plants have blocked waterways, impeding boating access and water conveyance for agricultural irrigation and municipal drinking water. Furthermore, studies show aquatic plant infestations in neighboring waters can cause waterfront property values to decline up to 19 percent. Zebra mussels have been shown to colonize and clog water intakes and other water infrastructure, resulting in costly and ongoing maintenance and repairs. That includes costs to retrofit hydroelectric facilities in dams—costs that have been relayed to customers in the form of water and electric utility bill increases of up to 15 percent.

Recognizing what’s at stake, lawmakers in the last legislative session appropriated $6.3 million and five new employee positions for the 2016-2017 biennium to address statewide management of aquatic invasive species, an increase from $1.1 million in the previous two-year funding cycle. This unprecedented investment is allowing the department and its partners to implement (1) a nearly five-fold increase in the annual acreage of aquatic invasive plants treated, (2) expanded capacity to implement biocontrols (such as weevils that eat giant salvinia), (3) enhanced early detection and containment of zebra mussels and other species, (4) strategies to control invasive riparian plants (e.g. saltcedar and giant reed) primarily in the Hill Country and along rivers in the northwestern plains, (5) critical research to better assess the environmental and economic impacts of aquatic invasive species, and (6) enhanced outreach and awareness campaigns to encourage Texans to do their part to help prevent the spread of invasive species such as giant salvinia and zebra mussels.

The challenge of “scaling up” the scope and scale of TPWD’s aquatic invasive species control efforts also brings an opportunity to further engage external organizations as partners. Through new or expanded partnerships with universities, river authorities, municipal water districts, non-profits, local, state and federal agencies, local communities, and other partners, the agency is leveraging existing personnel, equipment and resources to deliver control and restoration projects more quickly and efficiently.

One major category of work is Aquatic Invasive Plant Management, projects focused on management of aquatic invasive plants on public waters to enhance boater access for recreation, rapid response to new infestations, and management of riparian (riverside) invasive plants in target areas to improve water quality and quantity and habitat quality. Partners and project areas include:

  • Lavaca Navidad River Authority – Control of water hyacinth, hydrilla and giant salvinia at Lake Texana
  • Sabine River Authority – Rapid response and early containment of a new infestation of giant salvinia at Lake Fork
  • Cypress Valley Navigation District – Control of aquatic invasive plants to maintain boat lanes at Caddo Lake and Big Cypress Bayou
  • Guadalupe-Blanco River Authority – Control of water hyacinth, hydrilla, and other problematic aquatic and riparian plants in the Guadalupe River and tributaries
  • Armand Bayou Nature Center – Control of water hyacinth on Armand Bayou and tributaries
  • Lower Neches Valley Authority – Control of giant salvinia at B.A. Steinhagen and Sam Rayburn reservoirs
  • Angelina and Nacogdoches Counties Water Control and Improvement District – Control of water hyacinth at Lake Striker
  • Contract herbicide applicators – Control of aquatic invasive plants on numerous rivers and reservoirs including Toledo Bend, Caddo Lake, Colorado River, and Pedernales River
  • Texas State Soil and Water Conservation Board – Management and control of giant reed along the Rio Grande
  • The Nature Conservancy – Large-scale treatment of giant reed on the Blanco River and tributaries
  • Nueces River Authority – Large-scale treatment of giant reed on the Nueces River and tributaries
  • Hill Country Alliance – Large-scale treatment of giant reed on the Pedernales River and tributaries
  • Texas Tech University Llano River Field Station – Large-scale treatment of elephant ear on the Llano River and tributaries
  • Devils River Conservancy – Landowner workshops and conservation demonstration projects to engage local landowners in control of riparian invasive plants along the Devils River
  • U.S. Fish and Wildlife Service (and others) – Control of saltcedar on the upper Brazos River
  • City of Gainesville, TX – Control of floating heart at Moss Lake

Another category is Research, with projects focused on developing innovative new control strategies to contribute to an overall Integrated Pest Management strategy, and providing important monitoring and analysis of the impacts of invasive species regulations and management efforts. These include:

  • Stephen F. Austin University – Development of biocides for control of giant salvinia
  • Texas A&M AgriLife Research – Technical assistance on establishment of native aquatic vegetation in Texas reservoirs (to fill a niche that would otherwise be filled by invasive aquatic vegetation)
  • Texas A&M University – Development of control strategies for invasive Suckermouth Catfish
  • Texas Tech University – Surveys to document the range of Asian Carp in Texas to better target management and outreach strategies
  • Zebra mussel ecology, impacts, and mitigation

Last but not least are public Outreach and Education, which enlist the help of citizens and are widely recognized as the most effective tools for preventing the spread of invasive species. These include:

  • Numerous partnering river authorities and municipal water districts – Zebra mussel and giant salvinia public awareness campaigns intended to prevent or slow the spread of these species to new water bodies (centered around the currently infested lakes)

For more information on invasive species in Texas, visit