Integrity is ONE of our Core Values, and Biotic Integrity is in our latest Basin Report Card highlight!

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Aquatic Biologist Zoe Nichols holds two Largemouth Bass during a fish survey.

Welcome to the River Authority’s Basin Report Card series!

In 2020, the San Antonio River Authority (River Authority) developed the San Antonio River Basin Report Card from the drive to harmonize the needs of people and nature through our stewardship of the San Antonio River Basin. The primary purpose of the Report Card is to shine a light on the healthy aspects of our watershed and those that may need improvement. We hope that the education and engagement of community members will spur change in both individual behavior and public policy decisions, actions, and investments that support a sustainable San Antonio River Basin.

The 2nd Annual San Antonio River Basin Report Card was released in September 2021 to correspond with World Rivers Day. The overall grade for the 2021 Report Card is a “B.” This was the same grade for 2020. This overall grade is based on the average of twelve indicator grades. With each following report card, the grades for the indicators will show trends that clearly demonstrate where progress is being made and where improvements are still needed. Each month we will highlight a specific indicator and its grade. Follow along to read how you can help improve the health of area creeks and rivers.

This month’s indicator may sound like a mouthful, but it’s simply a measurement of the health of fish populations in area creeks and rivers. It’s the Index of Biotic Integrity, or IBI, for short.

What is the IBI, and how do we measure it?

ESD staff capture sample fish using a seine net.

ESD staff Angelica Rapacz, Alex Mendietta, Zoe Nichols, and David Zoch use a seine net to sample fish communities.

The Index of Biotic Integrity (IBI) tool is used by our Environmental Sciences Department (ESD) staff to sample, evaluate, and describe the condition, or health, of the basin’s creeks and rivers. Among other factors, our scientists assess the abundance and variety of fish species and the health of individual fish in each of 20 river sites.

So, how did the basin do for 2021?

Mission Reach in downstream of Espada Dam.

A picture of the Mission Reach of the San Antonio River Walk downstream of Espada Dam.

The IBI rating for the 2021 Report Card is a C+  

This grade indicates that specific River Basin locations have healthy fish communities and the grade is up 2.6 points from the 2020 grade – Woohoo! However, the score does suggest that further improvements can be made to enhance the diversity and abundance of organisms living in the waterways throughout the basin. Reducing disturbances (e.g., flooding, urbanization, pollution) to area creeks and rivers can help protect and enhance the health of their biotic communities. Healthy ecosystems are more resilient to existing disturbances and typically have a higher species diversity. For more information on how we calculated this rating for 2021, see the full Basin Report Card.

Want more information about the health of the San Antonio River Basin?

Check out the San Antonio River Basin Summary Report. Last completed in 2018, this detailed report is completed by the River Authority every five years for the Texas Commission on Environmental Quality (TCEQ), and it provides a comprehensive overview of monitoring and assessment activities in the San Antonio River Basin, including information on the levels of bacteria, nutrients, and other water quality parameters. Each year, except the years when the larger Basin Summary Report is produced, the River Authority creates Basin Highlight Report for the TCEQ. The most recent version is the 2021 Basin Highlights Report, and it includes an overview of basin water quality monitoring activities, including a review of water quality data, maps showing the location of sampling sites, and public outreach activities. You can also visit our Water Quality Viewer to see a GIS map that displays the monitoring efforts the River Authority conducts for the TCEQ and summarizes how the water quality in the San Antonio River Basin compares to the Texas Surface Water Quality Standards.

What can I do to help improve our rating?

A hand holds a large apple snail discovered in the San Antonio River.

Giant apple snails (Pomacea maculata) are native to South America and are a highly destructive invasive species throughout Texas.

One thing you can do to help is to please remember, never dump your aquarium into the river or any other freshwater or saltwater body! The River Authority is currently responding to invasive apple snails that have been found in the San Antonio River Walk. Unfortunately, this invasive species has been carelessly introduced into our basin by people who have illegally dumped their fish tanks into the river. These snails have few native predators and are voracious herbivores. If they were to establish in the Mission Reach (or anywhere further south, including the southern basin), they would pose an even more significant threat than they do now.

View the Full Report Card for info on more ways you can help. Together, we can achieve and maintain good grades in the annual San Antonio River Basin Report Card. See you next month for our score on Paddling Standards!

Coming soon to a blog near you…

A young man holds a Guadalupe bass in his hands.

Watershed Monitoring Scientist Adrian Reyna holds a Guadalupe bass, the state fish of Texas. 

Want to learn more about the fish species that call the San Antonio River Basin home? Stay tuned for an upcoming blog series about the annual Mission Reach Intensive Nekton Survey (MRINS). We’ll dive into the purpose and methods of the survey, as well as the exciting discoveries we made in 2021!

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