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San Antonio River Basin Report Card

2020

Report Card Summary

2020
San Antonio River Basin Report Card Summary
The overall grade for the 2020 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.
66.2
Paddling Standard
Paddling Standard
How is this being measured?
Explanation of the grade
Key findings

APaddling Standard

While all the metrics in the San Antonio River Basin Report Card have overlapping correlation to the safe, clean, enjoyable creeks and rivers aspects of the River Authority’s mission, the Paddling Standard grade is primarily related to the clean and enjoyable aspects.

From its calm, peaceful flow through the urban environment of the San Antonio River Walk, to its wild, unpredictable rural stretches, the San Antonio River is fantastic for paddling recreation. Similar to the Swimming Standard, this metric relates to the quality of life and health of area citizens who live in the River Authority’s District as well as to promoting increased preservation and conservation of the San Antonio River Basin resources by individuals, businesses, and government.

Secondary Contact Recreation 1 Standard

Just as too much bacteria can cause problems for those who want to swim or wade in the river, too much bacteria can also be problematic for paddlers as well. For the Paddling Standard, similarly to the Swimming Standard, the River Authority measures Escherichia coli (E. coli) bacteria as an indicator of recent fecal contamination to area waterways. E. coli comes from the gut of warm-blooded animals, and while most strains are not typically harmful to humans, it is a measure of recent fecal contamination. Fecal matter may contain disease-causing bacteria, viruses, or protozoans. Typical sources of E. coli include wildlife, domestic animals, and humans. When it rains, E. coli levels in our creeks and rivers rise exponentially. This is because as it rains, stormwater runoff washes over the land, carrying fecal matter into nearby creeks and rivers.

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 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.

Secondary Contact Recreation 1 Standard

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).

Explanation of the grade

Based on data from the River Authority’s Water Quality – Bacteria Dashboard there are 65 sites meeting the Secondary Contact Recreation 1 Standard out of 72 total sites.

Grade: A
(65/72 x 100 = 90.3%)

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. Another similarity between six of these seven locations is that paddle recreation is not allowed in these areas per the City of San Antonio. Of these six locations where paddling is not allowed, five are in the upper most reaches of the San Antonio River and one is located on Apache Creek, which is tributary to the upper San Antonio River.

Therefore, the key finding for this grade is that the Secondary Contact Recreation 1 Standard is being meet at every water quality monitoring location along the San Antonio River, except one, where paddle recreation is allowed.

Secondary Contact Recreation 1 Standard
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