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San Antonio River Basin Report Card 2022

San Antonio River Basin Report Card Summary
The overall grade for the 2022 San Antonio River Basin Report Card is B. This grade is the average of twelve individual indicator grades, which are explained in greater detail below.
Paddling Standard
Paddling Standard
How is this being measured?
Explanation of the grade
Key findings

APaddling Standard

It is critically important for clean freshwater to flow throughout the San Antonio River Basin (instream flows) and to reach the bays and estuaries of the Texas Coast (freshwater inflows). No matter where you live in the San Antonio River Basin, you can help protect instream flows and freshwater inflows. An important lesson to learn is that habitats and ecosystems are connected within the San Antonio River Basin – actions in the upper reaches of the basin can have impacts throughout the basin, including into the bay.

Paddling on the San Antonio River Walk - Mission Reach


Droughts can have an impact on the various human and environmental demands for freshwater. You can see current maps about the Drought Impact on Surface Waters in Texas, Texas Vegetation Conditions, and Drought Conditions along with learning more about drought in Texas here. One way you can help is to do your part by being mindful of how often you water your traditional lawn. Implementing water conservation practices throughout the year, particularly in Bexar County, can help maintain enough water in the Edwards Aquifer to keep spring flow entering the San Antonio River. Doing away with a traditional lawn that uses non-native, and often, water-intensive vegetation is even better. You can do this by implementing xeriscape landscaping using native vegetation which is designed specifically to reduce or eliminate the need for supplemental water from irrigation.

You could even go one step further and use native vegetation at your home or business while implementing green infrastructure, which are types of multi-benefit best management practices recommended for helping not only to limit the need for supplemental water irrigation, but also improve water quality and help reduce flooding, particularly in urban areas. Homeowners can harvest rainwater in a rain barrel and use that water to irrigate their yard or build a rain garden to help capture and filter rain water runoff on your property. Utilizing green infrastructure practices to improve water quality is not only for urban areas. Owners of farms and ranchland can develop a water quality management plan for their property with assistance from their local soil and water conservation district to help mitigate runoff pollution from rural areas. Helping to clean rainwater runoff and better managing water quantity concerns are some of the myriad reasons the River Authority is encouraging individuals, businesses, and governmental collaborators to implement green infrastructure throughout the San Antonio River Basin.

Climate change also has the potential to impact instream flows (and freshwater inflows). A 2016 summary produced by the Environmental Protection Agency about what climate change means for Texas shows that despite the likely increase in heavy storms, the changing climate is expected to make water less available overall, and “Increased evaporation and decreased rainfall are both likely to reduce the average flow of rivers and streams.” Further evidence of the threat of climate change is identified in the City of San Antonio’s SA Climate Ready Report which states that climate projections for the city’s future will likely be even hotter and drier, and that “By 2040, we will likely experience summer maximum temperatures 4°F higher on average, 24 additional days over 100°F each year, and 3” less rain each year.” This evidence coupled with the recent (2021) Intergovernmental Panel on Climate Change report noting that the Central North America region, including the San Antonio River Basin region, is projected to see increases in drought, extreme precipitation, and river flooding provides a clear picture of changes that the San Antonio River may soon face.  

You can learn more about climate change and steps you can take to help from the U.S. Fish & Wildlife Service, Environmental Protection Agency, United States Geographic Survey, and The Nature Conservancy.

How is this being measured?

The River Authority has an extensive water quality monitoring program that compiles and reports data on a variety of contaminants in the water to the State. For this metric, the contaminant of importance is E. coli bacteria. The River Authority uses a geometric mean to determine the type of contact recreation at a given location. It is an average of water quality testing results over time. The geometric mean criterion for E. coli for the Secondary Contact Recreation 1 Standard is 630 MPN (most probable number) per 100 mL. This regulatory surface water standard set by the Texas Commission on Environmental Quality (TCEQ) refers to water recreation activities which commonly occur, but have limited body contact with the water, and are presumed to pose a less significant risk of water ingestion than the Primary Contact Recreation 1 Standard. Water recreation activities such as kayaking and paddling are suitable for this standard. Thus, for the sake of simplicity in this basin report card, we have decided to use an informal name for this metric and will call it the Paddling Standard rather than using the formal regulatory name of Secondary Contact Recreation 1 Standard.

Putting in along the SASPAMCO Paddling Trail


The grade for this metric uses the water quality monitoring data collected by the River Authority. The past five years of data is used to determine this grade by dividing the number of water quality monitoring sites that meet the Secondary Contact Recreation 1 Standard by the total number of sites monitored in the basin and multiplying that number by 100. Therefore, the grade for this metric is based on the percentage of monitoring sites that meet the regulatory Secondary Contact Recreation 1 Standard (i.e., Paddling Standard). It is important to note that 76 monitoring stations were identified last year (2020-2021) and 71 monitoring sites this year.

Explanation of the grade

Based on data from the River Authority’s Water Quality – Bacteria Dashboard there are 64 sites meeting the Secondary Contact Recreation 1 Standard out of 71 total sites.

64/71 x 100 = 90.1%

Grade: A

Key findings

Like the Swimming Standard metric, annual rainfall rates can also impact the Paddling Standard report card grade. National Weather Service rainfall data for the last five fiscal years can be found here. (Note: The River Authority’s fiscal year runs from July 1 to June 30.) Years that have more rainfall are likely to have an increase in E. coli levels as bacteria levels tend to rise dramatically in the river following rain events, particularly in urbanized areas with large amounts of impervious cover.

The data and corresponding basin report card grade indicate that E. coli bacteria levels monitored in the San Antonio River often meet the state surface water quality geometric mean criterion for the Secondary Contact Recreation 1 Standard. Looking closely at the data, the commonality between the seven sites that did not meet this standard is that they are all located in highly urbanized areas of San Antonio. Of note, the station sites that did not meet the paddling standard this year are the same sites that did not meet the paddling standard last year.

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Find out more about sustainability and getting involved in helping protect your river, including watershed cleanup projects, building a rain garden, and much more.