Zebra Mussel Monitoring Program

The zebra mussel (Dreissena polymorpha) is an invasive species that has spread rapidly in the United States. The first confirmed detection of zebra mussels in Texas occurred in 2009 at Lake Texoma along the Texas–Oklahoma border. As of February 2021, 23 lakes in Texas are infested with zebra mussels according to the Texas Parks and Wildlife lake status.

The Zebra Mussel Monitoring Program for Texas (ZMMP) began in April 2010 and has expanded over time in response to the continued spread of zebra mussels in Texas. The ZMMP focuses on presence/absence, early detection, and spatio-temporal population dynamics of larval (veliger) and juvenile or adult zebra mussels in locations across Texas. The ZMMP also incorporates water quality monitoring and sampling to learn which water-quality thresholds may limit (or accelerate) zebra mussel distribution.

Zebra mussel counts/densities, water-quality data, lake status, and other information about the locations we monitor are available through the map below or the individual locations linked in the navigation bar.

Zebra Mussels vs. Quagga Mussels
zebra mussel next to quagga mussel

Zebra mussels (Dreissena polymorpha, left) and quagga mussels (Dreissena rostriformis bugensis, right) are both invasive species. They are closely related and are jointly referred to as dreissenid mussels.

The ZMMP includes inspections for both invasive species but has not yet detected quagga mussels at any Texas location.

Photo courtesy of the USGS Nonindigenous Aquatic Species Web Site.

Detection and Monitoring

The ZMMP uses a suite of detection and quantification methods to determine spatial distributions, dispersal, spread, population dynamics, and reproductive phenology of both zebra and quagga mussels.

Microscopic view of water sample; three zebra mussel with lengths of 223, 130, and 115 micrometers are visible

Collecting and analyzing water samples for larvae (veligers).

Zebra mussels covering substrate block in the foreground.   A clean (pre-deployment) substrate block is visible in the background.

Monitoring juvenile and adult mussel settlement and growth on artificial substrates.

Two scuba divers in the water near a safety buoy

Identifying adult zebra mussels through SCUBA and video inspection.

Female scientist in a boat, holding a plastic bag containing a plastic bottle recently filled with water from the lake for water quality analysis.  A water cooler for storing the samples is directly behind her.

Collecting and analyzing water quality data.

Explore the Data

ZMMP Interactive Map

Open the ZMMP Interactive Map to see the latest zebra mussel detections and USGS sites for sample collection.

Screenshot of the interactive zebra mussels map

Data Resources

USGS Resources

Texas Resources