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Urban and Rural Nonpoint Source Best Management Practices Improve
Water Quality in the Upper San Antonio River
Wafprhnrk/ Imnrnx/pH T'ie Upper San Antonio River was listed as not meeting the contact
recreation use in the 1992 Texas Water Quality Inventory and
Clean Water Act (CWA) section 303(d) list (1992 Integrated Report [IR]). Multiple state and federal
agencies have worked with local stakeholders to improve water quality in the Upper San Antonio
River, including the Texas Commission on Environmental Quality (TCEQ), the Texas State Soil and
Water Conservation Board (TSSWCB), and the U.S. Department of Agriculture Natural Resources
Conservation Service. The development and implementation of a watershed protection plan (WPP),
urban and agricultural best management practices (BMPs), and local stakeholder engagement has
helped reduce the concentration of bacteria in the Upper San Antonio River. Based on instream
water quality data, AU 1911_02 now meets the bacterial water quality standard and was delisted in
the 2016 IR.
Problem
The Upper San Antonio River (Segment 1911) is divided
into nine assessment units. AU 1911_02 is southeast
of the city of San Antonio in Wilson County (Figure 1).
While this AU is downstream of a major city, the sur-
rounding land is primarily pasture and cultivated crops.
The Upper San Antonio River was listed as impaired for
elevated fecal coliform in the 1992 IR. Beginning with
the 2002 IR, the TCEQ transitioned from performing
water body assessments using fecal coliform to using
the indicator bacteria Escherichia coli (E. coli). The
water quality standard for primary contact recreation
in surface waters states that the geometric mean
concentration of bacteria should not exceed 126
colony-forming units (cfu)/100 milliliters (mL) of water.
When first listed for E. coli in the 2006 IR, AU 1911_02
had a geometric mean of 184 cfu/100 mL.
Story Highlights
With funding from the U.S. Environmental Protection
Agency (EPA) and the TCEQ, the San Antonio River
Authority completed a WPP In 2006, updated the
WPP (accepted by EPA in 2015), and Implemented two
projects from 2006 through 2018. The WPP analyses
Figure 1. The Upper San Antonio River watershed is in
south-central Texas.
indicated that a 30 percent reduction in bacteria load-
ing from stormwater sources was needed across the
watershed. As a result, subsequent implementation
projects targeted urban and rural nonpoint sources,
prioritizing low impact development (LID) and educa-
tion and outreach to ci tizens for implementation.
i-f, Braunh
San Antonio
Legend
	1911_02AU
	Upper San Antonio River
• TCEQ Nonpoint Source BMP Sites
I WPP Area

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160

140
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2006
The TCEQ also partnered
with the Texas A&M
Agrilife Research outreach
program "Healthy Lawns
Healthy Waters" to edu-
cate homeowners about
rainwater management
and lawn and landscap-
ing practices through
presentations, education
materials, and providing
free soil analysis.
An early example of WPP
implementation dates to
2008 when CWA section
319(h) funds paid for
power washers to be
used on the San Antonio
River Walk. This practice
diverts runoff that would
otherwise run directly into
the San Antonio River through sanitary sewers.
An example of education and outreach to citizens can
be found in the highly visible BMP implementation at
the San Antonio Mission Public Library. The library's
proximity to the San Antonio River made it an ideal
location to demonstrate LID features to the public and
educate developers. The constructed features include
surface retention and infiltration structures, bioswales,
stormwater roof collection systems and rain gardens.
Construction was completed in spring 2012; monitor-
ing results before and after installation demonstrate
a reduction in the amount of stormwater runoff and
pollutants leaving the site and entering the Upper San
Antonio River.
Since 2007, the TSSWCB has partnered with the
Karnes County and Wilson County soil and water
conservation districts (SWCDs) and local landowners to
implement BMPs on grazing land. Twelve water quality
management plans (WQMPs) have been developed
and certified in the watershed, covering 1,706 acres
of grazing land. Implemented management practices
include prescribed grazing, range planting, alternative
watering facilities, and forage and biomass planting.
The TSSWCB and SWCDs provide technical assistance
to landowners in the watershed.
E. coli in Upper San Antonio River
AU 1911_02
2008
2010
2012
2014
2016
Integrated Report Year
| Geometric Mean Assessed — Criteria (126 cfu/1 OOmL)
Figure 2. E. coli levels have declined in the Upper San Antonio River.
Results
Texas assesses bacteria in freshwaters for the IR by
comparing the geometric mean concentration of
E. coli samples collected during the assessment period
(typically a 7-year period of record) against the water
quality standard. The geometric mean concentration
of E. coli in the Upper San Antonio River AU 1911_02
decreased from 184 cfu/lOOmLto 106 cfu/lOOmL in the
10 years between the 2006 IR and the 2016 IR. A net
decrease in bacteria concentrations in the Upper San
Antonio River have been observed since implementa-
tion activities began (Figure 2). As BMPs recommended
in the WPP continue to be implemented and have
more time to become established, a greater decrease
in bacteria throughout the waterbody is expected.
Partners and Funding
Since 2007, watershed partners have spent approxi-
mately $1,854,913 on water quality improvements and
education and outreach efforts, combining $1,112,948
in federal CWA section 319(h) funds with $741,965
matched by local entities such as the City of San
Antonio, the San Antonio River Authority, and Karnes
County and Wilson County SWCDs. TCEQ and TSSWCB
continue to fund implementation projects in the Upper
San Antonio River watershed.
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U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA 841-F-19-001II
November 2019
For additional information contact:
Emily Fort, TCEQ
512-239-6693 • emily.fort@tceq.texas.gov
Brian Koch, TSSWCB
bkoch@tsswcb.texas.gov

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