San Marcos River Watershed Monitoring Stations – RM 150 San Marcos River Blanco FM 535 FM 2001 1815 River

HAYS FM 1185 FM 812 BI 35J RM 150 12672-G San Marcos River at IH 35 in 1813 ® San Marcos FM 1854 12671-T San Marcos River 0.7 m downstream FM 672

FM 2720 RM 32 of IH 35 in San Marcos FM 1966 RM 12 12628-T San Marcos River downstream of SINK CR FM 20 *A  FRQÁXHQFHZLWK%ODQFR5LYHU SH 21 # SH 142 SAN MARCOS SL 82 12626-G San Marcos River at Luling 1809 12672-G 12671-T FM 1984 16578-G San Marcos River at SH 90A, near FM 3407 " York Creek MARTINDALE LOCKHART Gonzales PR 10 12628-T FM 713 FM 2673 " FM 1979 FM 1322

IH 35 FM 621 US 183 SH 80

Long Creek FM 2439 FM 1978 Dickerson Creek FM 86 FM 3158

COMAL FM 671 Caney Creek FM 1977 FM 306 WaterFM Hole 1102 Creek

FM 1979 Callihan Creek

RM 2722

FM 2984 CALDWELL

FM 3353 3353 FM FM

Mesquite Creek FM 483 FM 1339 YORK CR FM 20 " SAN MARCOS R FM 1863 FM 1101 BS 46C FM 758 US 90 BI 35H

SL 337 LULING Mule Creek FM 2623 12626-G Wolf Creek "# FM 482 SH 46 1808 US 90 " US 183 GUADALUPE "

FM 1104 Highsmith Creek

SH 304 304 SH SH

Smith Creek

FM 725

SH 123 SH Legend 123 SH

FM 2438 Monitoring Station Artesia CreekCanoe Creek

PR 11

Stream Segment Smith Creek FM 1586 FM 1044 " Segment Boundary FM 1150 "

Tributary SH 97

BS 123B BS FM 464 123B BS WatershedFM 78 Boundary Dry Fork FM 2091

FM 794 City 1808 SH 80 GONZALES Oil Reserve FM 465 FM 725 FM 466 GONZALES 16578-G FM 532 FM 775 UA 90 Sampling sites are labeled in red followed by FM 467 FM 477 " DomesticIH 10 WW Permit SS 146 the letter G (GBRA), T (TCEQ), U (UGRA) or W

" Texas Land Application Permit FM 2091 FM 1117 FM FM 1117 FM (Wimberley) indicating who is the monitoring entity. # USGS Gage

San Marcos River Watershed Vegetation Cover: Water Body Uses: Aquatic Life Use, Contact Recreation Pasture/Hay- 27.0% Evergreen Forest - 12.8% Use, General Use, Fish Consumption Use, and Drainage Area: 522 square miles Grass/Herbaceous - 16.3% Shrublands - 12.2% Public Water Supply Use Streams and Rivers: Lower San Marcos River, Deciduous Forest - 19.0% Row Crops - 8.6% Upper San Marcos River, Sink Creek, York Creek Climate: Soils: Varies from thin limestone to black, waxy, Aquifers:Edwards-Balcones Fault Zone, Carrizo-Wilcox Average annual rainfall: 33 inches chocolate, and grey loam River Segments: 1814, 1808 Average annual temperature: January 40° July 96° Permitted Wastewater Treatment Facilities: Cities: San Marcos, Maxwell, Martindale, Fentress, Land Uses: Urban, Industry, Agricultural Crops (corn, Domestic: 4, Land Application: 2, Industrial: 0 Prairie Lea, Luling, Ottine, Gonzales sorghum, hay, cotton, wheat, pecans), Cattle & Hog Counties: Hays, Guadalupe, Caldwell, Gonzales Production, Poultry Production, Oil Production, and Recreation EcoRegion: Edwards Plateau, Post Oak Savannah, Texas Blackland Prairies

- 66 - 2008 Basin Summary Report Wastewater Contributions

RM0012RM 12 In addition to the city of San Marcos’s Wastewater Treatment Plant (WWTP), CREEKK CR there is one other wastewater discharge to the segment. The Texas Parks and SH 21 SH0021 Wildlife Department’s A.E. Wood Fish Hatchery manages a concentrated aquatic 1814 SAN MARCOS 1814

FM 2325 7 FM1854 SLSL0082 82 Blanco River SAN MARCOS RM3237RM 323

FM2001 18151815 US0183 animal production general permit. The General Permit (TXG130005) requires

BI0035J HAYS FM1185 RM0150RM 150 ek 1813 RM 12 ! FMFM1984 1984 1809 12672-G® PHDVXULQJDQGUHSRUWLQJÁRZRQFHGDLO\GDLO\PD[LPXPWRWDOVXVSHQGHGVROLGVRI 1809 FMFM3407 3407 1808 RM0032 RM 32 FMFM2720 2720 12672" FMFM1966 1966 RM0012RM 12 Purgatory CreekSINKSINK CREEK CR Plum Creek ! 90 milligrams per liter (mg/L) monitored once per month; dissolved oxygen of 5.0 FM0020 SH 21 FM 20 SH0021

1814 SAN MARCOS 1814 SH 142 SAN MARCOS SLSL0082 82 12628-T12628 MAXWELL FM1984 *A mg/L monitored once per week; carbonaceous oxygen demand of 250 pounds per ! FM 1984 12672-G FM 713 York Creek FMFM3407 3407 LOCKHART 12672" 1808 FM 20

FM 306 York Creek ! 183 US SH0142SH 142 PR0010 FM0713 12628 SH0123 FM2673 12628-T MARTINDALE " SH0123 FMFM1322 1322 IH 35 day maximum reported once per month and an ammonia daily maximum of 2.0 IH 35 SH 123 IH0035 SH 123 IH0035 " FMFM1979 1979 Long Creek FM2439 FM1978 FM 2439 FM 1978 Dickerson Creek FM 86 Dickerson Creek 439 FM0086 FMFM3158 3158 78 FM1979 FM0621 439 FM 1979 FM 621 FM 671 978 COMAL FM0671 " mg/L. The city of San Marcos wastewater plant is permitted to discharge 9 million Caney Creek FMFM1977 1977

FM0306 Caney Creek FM 306 WaterFMFM1102 Hole 1102 Creek

1808 Callihan Creek FMFM1979 1979 Callihan Creek

RM2722 gallons per day. After a lengthy court battle, the San Marcos River Foundation was

FENTRESS CALDWELL

US 183 183 US

SH0304

FM3353

FM 3353 3353 FM SH 304 304 SH

FM 671 ek Creek Saols Mesquite CreCreek FMFM2984 2984 IHFM0483 35 FMFM1339 1339 YORK CR FM0020 PRAIRIE YORK CREEK LEASAN MARCOS R FM 20 VXFFHVVIXOLQJHWWLQJWKHFLW\·VHIÁXHQWWUHDWHGWRDKLJKHUTXDOLW\7KHHIÁXHQWPXVW BS0046C FMFM1386 1386 FM1863 San Marcos FMFM1101 1101 SHSH0080 80 River BI0035H

SL0337 LULING FM0758 Mule Creek US0090US 90 Brushy Creek Mule Creek meet high quality standards of 5 mg/L biochemical oxygen demand, 5 mg/L total FMFM2623 2623 12626-G FM0725 Wolf Creek SH0046 Wolf Creek ! FM0482 12626 IH 10 US0090 " Legend GUADALUPE US 90 Highsmith Creek FM1104 Highsmith Creek FM 1104 suspended solids, 2 mg/L ammonia-nitrogen and 1 mg/L total phosphorus. The ! Monitoring Station SmithSmith Creek Creek

River FM2438 " HWY 123 B B 123 HWY Artesia Creek FM 20 FM 2438 Artesia CreekCanoe Creek

PR 11 Segment Boundary PR0011 IH 10 OTTINE Smith Creek FM1586FM 1586 US0183 wastewater plant utilizes ultraviolet light for disinfection and is allowed to discharge Smith Creek US 183 Tributaries FM1044 "

FM2091 Watershed Boundary FM 2091 FM0464 BS0123B USUA0090 90A City FM0078 Dry Fork SH 97 up to 200 organisms per 100 milliliter of fecal coliform bacteria. The wastewater

SH0097 HWY 123 123 HWY

FM0794 FM 794 FM1150 Oil Reserve FM 1150 1808 SH 80 County with significant poultry activities SH0080 FM0465 FM0725 5052.5 BU0183V ® Road Miles GONZALES FM0532FM 532 SODQWKDVUHFHLYHGDXWKRUL]DWLRQIURPWKH7&(4WRUHXVHWKHHIÁXHQWIRULUULJDWLRQ FM0775 FM0477 ! County Line SS0146 IH0010 16578-G16578 SS 146

FM0467

# Industrial WW Permit FM 2091

FM2091 GONZALES FM1117 FM1117 FM1117 FM1117 FM0466 on golf courses and dust control, when possible. The Gary Job Corps Center (GJCC), " Domestic WW Permit " Texas Land Application Permit located along this segment, no longer discharges treated wastewater to the San  7KH6DQ0DUFRV5LYHULVGLYLGHGLQWRWZRFODVVLÀHGVWUHDPVHJPHQWV6HJPHQW Marcos River. The GJCC discontinued its treatment of wastewater in 2000 and 1814, the upper San Marcos RiverH[WHQGVIURPWKHFRQÁXHQFHRIWKH6DQ sends its raw wastewater to the San Marcos WWTP. Marcos and Blanco Rivers, just outside the city of San Marcos, to the headwaters of the river in and around Spring Lake within the city. The segment is 4.5 miles long Endangered Species and is separated into four assessment units: the lower 1.5 miles; from that point to IH 35; from IH 35 to Spring Lake; and, the remaining portion of the segment to the The San Marcos River is home to the Texas Wild Rice and fountain darter, headwaters. The lower San Marcos, segment 1808, is described in the following ERWKHQGDQJHUHGVSHFLHV7KHFRQVWDQWWHPSHUDWXUHDQGFRQVLVWHQWÁRZPDNH section. GBRA has been monitoring the San Marcos River at IH 35 (site no. 12672) the conditions conducive to these unique species as well as other native and quarterly since 1998. The GBRA site is located in the upper half of the segment, QRQQDWLYHDTXDWLFÁRUDDQGIDXQD7KH7H[DV:LOG5LFHLVLQGDQJHURIEHLQJ above the discharge of the city’s wastewater treatment plant but below the city’s out-competed by an invasive non-native aquatic plant, cryptocoryne, also known as downtown and business district. TCEQ has one historical site less than one mile water trumpet. Water trumpet is a fast-growing rooted aquatic plant with no natural downstream of the GBRA site that has data from 1991 to 1997. TCEQ monitored predators. In addition to the damage it poses to Texas Wild Rice, water trumpet is this site two to four times per year. There are other TCEQ sites in this segment but replacing the habitat that the fountain darter relies on. Removal or control of this with very limited data sets. LQYDVLYHSODQWLVGLIÀFXOWEHFDXVHLWLVIRXQGFRPPLQJOHGZLWKWKHZLOGULFH*HQWOH removal techniques, that are very labor intensive, have been employed so as to not Stakeholder Concerns uproot or damage the wild rice. The cryptocoryne is an example of the damage that can come from introduction of non-native species, in this case, most likely The stakeholders, primarily the San Marcos River Foundation, have asked that introduced by people disposing of the contents of their aquariums. Other species TCEQ locate a monitoring site downstream of the city’s discharge. The closest that are associated with the improper disposal of aquarium populations include monitoring station downstream of the discharge is at site no. 12629 (approximately loriicarids (algae eaters), hydrilla and the giant ram’s horn snail. 0.5 miles) but only four sampling events were conducted in 1999-2000. When asked at a basin steering committee meeting, representatives of the TCEQ Region Water Quality RIÀFHH[SODLQHGWKHGLIÀFXOW\RIJHWWLQJSXEOLFDFFHVVIRUDPRQLWRULQJVLWHLQ close proximity and downstream of the wastewater treatment plant. The San  7KHVWUHDPVHJPHQWLVKHDYLO\LQÁXHQFHGE\VSULQJVIURPWKH(GZDUGV$TXLIHU Marcos River Foundation offered to assist in locating a landowner that could grant located in the hills above the city and in Spring Lake. The springs discharge a public access to the regional Surface Water Quality Monitoring team. TCEQ has a PHGLDQÁRZRIFXELFIHHWSHUVHFRQG7KHÁRZIURPWKHVHVSULQJVNHHSV quarterly monitoring site that is 3 miles downstream of the city’s discharge. The 44 the temperature in the upper San Marcos River stable, at a median temperature data points span 1990 to 2007. Data from this site will be discussed in the next of 22.8ºC, ranging from 19.2 ºC to 25.2ºC. Figure 1 shows how stable the section on segment 1808. temperature of the upper San Marcos River is. The exception is during times of - 67 - 2008 Basin Summary Report prolonged drought as seen in 2006 where, in the data set collected by GBRA, phosphorus was detected in a sample it did not exceed the screening concentration WKHVLWHH[SHULHQFHGLWVKLVWRULFDOPD[LPXPWHPSHUDWXUHDQGPLQLPXPÁRZ7KH of 0.69 mg/L. The median chlorophyll a concentration is less than detection LQYHUVHUHODWLRQVKLSEHWZHHQWHPSHUDWXUHDQGÁRZZRXOGQRWEHXQXVXDORU and there was never a measured value above the screening concentration of 14.1 alarming at most sites, but with the existence of the endangered species that live in microgram per liter. WKLVVHJPHQWDQGUHO\RQWKHFRQVLVWHQF\RIWHPSHUDWXUHDQGÁRZPDLQWDLQLQJWKH ÁRZIURP6DQ0DUFRV6SULQJVLVFULWLFDOWRPDLQWDLQLQJWKHLUKDELWDW Water and Land Uses

Segment 1814 is known for its contact recreational opportunities. The clear, cool Flow vs. Temperature VSULQJZDWHUDWWUDFWVUHFUHDWLRQLVWV7KHÁRZVIURPWKHVSULQJVFUHDWHH[FHOOHQW conditions for snorkeling, tubing and canoeing. The San Marcos River is home to 400 the Texas Water Safari, one of the world’s largest canoe races. The race attracts 29 over 150 canoeing teams each June. The stream standard for contact recreation 27 300 25 is a geometric mean of 126 organisms per 100 milliliters, and a single sample 23 200 concentration of 394 organisms per 100 milliliters. The geometric mean for E. coli 21 at the GBRA IH 35 site is 34 organisms per 100 milliliters. In the period of record 19 100 no sample collected exceeded the 17 15 0 single sample E. coli standard of 394 organisms per 100 milliliters. The Jul-01 Jul-02 Jul-03 Jul-04 Jul-05 Jul-06 Jul-07 TCEQ monitored their site for fecal date coliform bacteria before a contact recreation standard was established temperature, oC flow, cfs for E. coli. The geometric mean for fecal coliform bacteria at the TCEQ Figure 1. Flow and temperature collected by GBRA at the IH 35 site on the upper San Marcos River site was 39 organisms per 100 (12672). milliliter (contact recreation standard for fecal coliform is a geometric mean The 2008 draft Texas Water Quality Inventory has no impairments or concerns of 200 organisms per 100 milliliters), listed for Segment 1814. The water quality at the GBRA and TCEQ monitoring with only one sample exceeding sites is very good. The median concentration for dissolved oxygen is 9.35 mg/L, the single sample standard of 400 ranging from a minimum of 7.0 mg/L to a maximum of 13.0 mg/L. At no time in organisms per 100 milliliters. the period of record did the dissolved oxygen drop below the minimum dissolved oxygen standard (4.0 mg/L). The VSHFLÀFFRQGXFWDQFH ranged between 263 The land use in the segment and 569 micromhos per centimeter, with a median conductivity of 425 micromhos consists of a highly urbanized area above the two monitoring locations and urban per centimeter. The median pH was 7.67, ranging from 6.9 to 8.06 standard units, area to large tracts of farmland below the two monitoring sites. Many of these never falling outside the stream standard range of 6.5 to 9 standard pH units. family farms are being sold and subdivided, so you are beginning to see more The median concentrations for chloride and sulfate were 19.2 and 25.3 mg/L roof tops in the watershed than cows. The impervious cover created by these respectively. At no time did the concentration of these dissolved constituents urbanized areas and subdivisions, i.e. streets, rooftops and parking lots, can exceed the stream standard of 50 mg/L. be a source of nonpoint source pollution. Because of the impervious cover, the pollutants that might be captured and bio-degraded by soils, are instead readily Nitrate nitrogen, ammonia nitrogen and total phosphorus were analyzed at washed over cement and pavement, directly into the surface water bodies. The the GBRA and TCEQ locations. Over the period of record, nitrate nitrogen was suspended solids at the two monitoring sites ranged from 1 to 32 mg/L, with a reported under three storet codes, as nitrate nitrogen and in combination with median of 3 mg/L. The sediment at the GBRA monitoring location in this segment nitrite nitrogen. The median concentrations for all three methods were 1.18, LVVODWHGIRURUJDQLFVDQDO\VLVLQVSHFLÀFDOO\ORRNLQJIRUWKHFRQVWLWXHQWV 1.13, and 1.23 mg/L, ranging from 0.29 to 2.26 mg/L. Regardless of storet code associated with urban environments, such as polyaromatic hydrocarbons. citing, only two samples exceeded the nitrate nitrogen screening criteria of 1.95 mg/L. The median ammonia nitrogen concentration, combining the GBRA and The historical data from the two monitoring sites was reviewed for trends, TCEQ sites, was 0.03 mg/L, ranging from 0.03 to 0.14 mg/L; never exceeding FRPSDULQJFRQVWLWXHQWVRYHUWLPHDQGÁRZUHJLPHV6WDWLVWLFDOO\VLJQLÀFDQWWUHQGV the screening concentration of 0.33 mg/L. The median total phosphorus that were noted, either positive or negative, were not indicative of degrading water FRQFHQWUDWLRQZDVEHORZWKHOLPLWRITXDQWLÀFDWLRQIRUWKHPHWKRGDQGZKHQWRWDO quality conditions.

- 68 - 2008 Basin Summary Report 6 FM *A In addition to the city of San Marcos’s Wastewater Treatment Plant (WWTP) # SH 21 SL 82 SH 142 1809 2672-G located in the upper segment, there is one other wastewater discharge to the 12671-T FM 1984 FM 3407 " MARTINDALE LOCKHART PR 10 segment. The city of Luling’s south plant discharges to the San Marcos River and 12628-T FM 71 " FM 1979 FM 1322

FM 621 US 183 is permitted to discharge up to 500,000 gallons per day. The facility is permitted SH 80

Long Creek

FM 1978 Dickerson Creek FM 86 to discharge total suspended solids of 20 milligrams per liter (mg/L), 20 mg/L FM 3158

FM 671

RM 150 FM 1977 Blanco biochemical oxygen demand, and ammonia-nitrogen of 2.0 mg/L. FM 535 FM 2001 1815 River

HAYS FM 1185 FM 812 BI 35J RM 150 FM 1979 1813 Callihan Creek ®

FM 1854 FM 2984 CALDWELL

FM 672

FM 3353 3353 FM FM

FM 2720 RM 32 FM 1966  7KHORZHU6DQ0DUFRV5LYHUKDVWZRPDMRUWULEXWDULHVWKDWFRQWULEXWHÁRZDQG RM 12 SINK CR FM 20 *A FM 1339 YORK CR FM 20 SH 21 # SH 142 SAN MARCOS SL 82 " SAN MARCOS R loading to the stream, the Blanco River and Plum Creek. The lower segment does 1809 12672-G 12671-T FM 1984 FM 3407 " York Creek MARTINDALE LOCKHART U 12628-T PR 10 FM 713 not have the endangered species that are found in the upper segment. The median FM 2673 " LULING FM 1979 FM 1322 Mule Creek

IH 35 FM 621 US 183 SH 80 FM 2623 Long Creek 12626-G FM 2439 Wolf Creek FM 1978 Dickerson Creek " FM 86 of the uppermost station in segment 1808 was 226 cubic FM 3158 # LQVWDQWDQHRXVÁRZ

COMAL FM 671 1808 Caney Creek FM 1977 US 183

FM 306 " WaterFM Hole 1102 Creek ALUPE US 90 FM 1979 " Callihan Creek Highsmith Creek feet per second (cfs) which is

FM 1104

SH 304 304 SH SH

Smith Creek RM 2722

FM 2984 CALDWELL

FM 3353 3353 FM FM

Mesquite Creek FM 2438 PDGHXSRIWKHFRPELQHGÁRZ FM 483 FM 1339 Artesia CreekCanoe Creek YORK CR FM 20 SAN MARCOS R " PR 11 FM 1863 FM 1101 BS 46C FM 758 SmithUS Creek 90 FM 1586 BI 35H of the San Marcos River and " SL 337 LULING Mule Creek FM 1150 FM 2623 12626-G Wolf Creek "# " FM 482 SH 46 1808 US 183 the Blanco River as measured

US 90 " BS 123B BS GUADALUPE 123B BS " Highsmith Creek

FM 1104 Dry Fork

SH 304 304 SH SH

Smith Creek

FM 725 SH 123 SH Legend 123 SH FM 2091

FM 794 FM 2438 at the USGS gages. There are Monitoring Station Artesia CreekCanoe Creek PR 11 1808 SH 80 GONZA Stream Segment Smith Creek FM 1586 FM 1044 " Segment Boundary FM 1150 " YHU\OLWWOHFRQWULEXWLRQVRIÁRZ FM 466

Tributary SH 97 16578-G

BS 123B BS FM 464 123B BS Dry Fork GONZALES WatershedFM 78 Boundary FM 477 FM 2091 City FM 794 SS 146 downstream of the Blanco to 1808 SH 80 GONZALES Oil Reserve FM 465 FM 725 ® FM 2091 FM 466 GONZALES 16578-G FM 532

FM 775 FM 1117 FM FM 467 FM 477 1117 FM UA 90 IH 10 SS 146 Luling so the concentrations of " Domestic WW Permit

" Texas Land Application Permit FM 2091

FM 1117 1117 FM FM # USGS Gage dissolved constituents remain  7KH6DQ0DUFRV5LYHULVGLYLGHGLQWRWZRFODVVLÀHGVWUHDPVHJPHQWV6HJPHQW relatively unchanged. The 1808, the ORZHU6DQ0DUFRV5LYHUH[WHQGVIURPWKHFRQÁXHQFHRIWKH6DQ median concentrations for Marcos and Guadalupe Rivers, just outside the city of Gonzales, upstream to the conductivity, chloride and FRQÁXHQFHZLWKWKHORZHU%ODQFR5LYHUQHDUWKHFLW\RI6DQ0DUFRVLQ+D\V&RXQW\ sulfate are 553 micromhos The segment is 75 miles long and is separated into four assessment units: the per centimeter, 18.5 milligrams ORZHUPLOHVIURPWKHFRQÁXHQFHZLWK0LOH&UHHNWRWKHFRQÁXHQFHZLWK3OXP per liter and 26 milligrams per &UHHNIURPWKHFRQÁXHQFHZLWK3OXP&UHHNWRWKH*XDGDOXSH&RXQW\5RDG liter respectively at the TCEQ DQGWKHUHPDLQLQJSRUWLRQRIWKHVHJPHQWWRWKHFRQÁXHQFHZLWKWKH%ODQFR5LYHU site just downstream of the The upper San Marcos, segment 1814, is described in the preceding section. GBRA Blanco River. The GBRA Luling has been monitoring the San Marcos River at Luling (site no. 12626) monthly since site had median concentrations 1987 and at the San Marcos at SH 90A (site no. 16578) quarterly since 1999. The of conductivity, chloride and sulfate of 552 micromhos per centimeter, 24.6 GBRA Luling site is located in the upper half of the segment, in the third assessment milligrams per liter and 28.7 milligrams per liter respectively. unit. The GBRA 90A site is in the lowest most assessment unit, just upstream of WKHFRQÁXHQFHZLWKWKH*XDGDOXSH5LYHU7&(4KDVRQHKLVWRULFDOVLWHORFDWHG Moving downstream, comparing the GBRA site at 90A to the GBRA Luling MXVWGRZQVWUHDPRIWKHFRQÁXHQFHZLWKWKH%ODQFR5LYHULQ+D\V&RXQW\ VLWHQR site, there is evidence of impacts to water quality by Plum Creek. The median 12628). TCEQ monitors this site two to four times per year. There are other TCEQ LQVWDQWDQHRXVÁRZDWWKH*%5$VLWHDW6+$ZDVFIVPDGHXSRIWKH sites in this segment but with very limited data sets. The statistical review of the FRPELQHGÁRZVRIWKH6DQ0DUFRV5LYHUDQG3OXP&UHHNLQFUHDVLQJWKHPHGLDQ data covered the three historical sites described above. ÁRZXSVWUHDPDWWKH/XOLQJVLWH7KHFLW\RI/XOLQJ·VZDVWHZDWHUWUHDWPHQWSODQW contributes less than 1.5 cfs to the San Marcos River. The GBRA 90A site had Stakeholder Concerns median concentrations of conductivity, chloride and sulfate of 610 micromhos per centimeter, 43.4 milligrams per liter and 35.1 milligrams per liter respectively. The At a Guadalupe River Basin Steering Committee meeting the stakeholders, GBRA Luling site exceeded the stream standards for both dissolved constituents primarily the San Marcos River Foundation, asked that TCEQ locate a monitoring site only once as well (Cl - 56.5 mg/L and SO4 - 63.8 mg/L). But, at the GBRA 90A site downstream of the city of San Marcos’ discharge. Representatives from the TCEQ GRZQVWUHDPRIWKHFRQÁXHQFHZLWK3OXP&UHHNWKHVWDQGDUGIRUFKORULGHVZDV 5HJLRQRIÀFHH[SODLQHGWKHGLIÀFXOW\RIJHWWLQJSXEOLFDFFHVVIRUDPRQLWRULQJ exceeded 20% of the time, ranging from 18.4 to 135 mg/L. The stream exceeded site in close proximity and downstream of the wastewater treatment plant. The San the standard for sulfate two times in the period of record. Plum Creek contributes Marcos River Foundation offered to assist in locating a landowner that could grant nutrients and bacteria to the San Marcos River as well. A more detailed discussion public access to the regional Surface Water Quality Monitoring team. The TCEQ’s of the water quality can be found in the section on Plum Creek. monitoring site in segment 1808 is 3 miles downstream of the city’s discharge. - 69 - 2008 Basin Summary Report Looking at each site individually and reviewing the data for trends, the conductivity shows a positive trend over time at the uppermost site as well as the *%5$/XOLQJVLWH ÀJXUHVDQG $OWKRXJKWKHUHZDVVWDWLVWLFDOO\VLJQLÀFDQWGDWD for more than one dissolved constituent that explained the slight rise over time in the conductivity at the uppermost site, the rise in conductivity at the Luling site is PRVWOLNHO\GXHWRDULVHLQVXOIDWH ÀJXUH 

Figure 3. Rise in sulfate concentration over time at the San Marcos River at Luling (12626).

The 2008 draft Texas Water Quality Inventory has no impairments or concerns listed for Segment 1808. The median concentration for dissolved oxygen is 9.0 mg/L, ranging from a minimum of 7.4 mg/L to a maximum of 10.8 mg/L at the 7&(4VLWHEHORZWKHFRQÁXHQFHZLWKWKH%ODQFR5LYHU$WWKH*%5$/XOLQJVLWH the median concentration for dissolved oxygen was slightly lower at 7.99 mg/L, ranging from a minimum of 5.2 mg/L to a maximum of 21.0 mg/L. The median concentration for dissolved oxygen was 8.81 mg/L, ranging from a minimum of 5.8 mg/L to a maximum of 11.7 mg/L at the GBRA 90A site. At no time in the data sets Figure 1. Rise in conductivity at the uppermost monitoring location on the lower San of all three monitoring locations did the dissolved oxygen drop below the minimum Marcos River (12628). dissolved oxygen standard (3.0 mg/L). The median pH values at the three sites were 7.8, 7.8 and 7.99, upstream to downstream, and ranged from a low of 7.13 to a high of 9.34, falling outside the stream standard range of 6.5 to 9 standard pH units one time at the GBRA Luling site.

The moderating effect of the San Marcos Springs on water temperature in the XSSHUVHJPHQWLVORVWDVWKHVWUHDPÁRZVGRZQVWUHDPWKURXJKWKHZDWHUVKHG7KH median temperature of the TCEQ site downstream of the Blanco was 23oC, ranging from 17.6 oC to 27.7oC. The median temperature at the GBRA Luling site was 22.8oC, ranging from 8.4 oC to 31.5oC, and the median temperature at the GBRA 90A site was 22.2oC, ranging from 12.1 oC to 30.3oC.

Nitrate nitrogen, ammonia nitrogen and total phosphorus, were analyzed at the GBRA and TCEQ locations. Over the period of record, nitrate nitrogen was reported under three storet codes, as nitrate nitrogen and in combination with nitrite nitrogen. At the TCEQ site in the upper part of the segment, the median concentrations for all three methods were 0.9, 1.1, and 1.28 mg/L, ranging from 0.42 to 1.88 mg/L. Moving downstream to the GBRA Luling site, the median concentrations for all three methods were 0.71, 1.06, and 1.25 mg/L, ranging from 0.18 to 8.51 mg/L, falling outside of the screening concentration of 1.95 mg/L three times. In the lower portion of the segment, the median concentrations for all Figure 2. Rise in conductivity over time at the GBRA Luling site on the San Marcos River three methods were 0.66, 1.02, and 1.03 mg/L, ranging from 0.38 to 1.83 mg/L. (12626). The median ammonia nitrogen concentration, at both GBRA sites, was 0.04 mg/L, - 70 - 2008 Basin Summary Report ranging from less than detection to 0.30 mg/L; never exceeding the screening HIÁXHQW7KHGRZQZDUGWUHQGLQWKHVHQXWULHQWVFRXOGEHDUHVXOWRIWKHLPSURYHG concentration of 0.33 mg/L. The median concentration for ammonia nitrogen of level of wastewater treatment by the city of San Marcos plant or it could just be the 0.07 mg/L at the TCEQ site was slightly higher than the downstream stations, and result of a change in detection level for each method in 1997. exceeded the screening concentration of 0.33 mg/L one time. The difference in the median concentrations may be from contributions from the wastewater treatment  6HJPHQWLVNQRZQIRULWVFRQWDFWUHFUHDWLRQDORSSRUWXQLWLHV7KHÁRZVLQ SODQWGLVFKDUJHPLOHVXSVWUHDPWKRXJKWKHLPSDFWLVQRWVLJQLÀFDQWHQRXJKWR the river create excellent conditions for snorkeling, tubing and canoeing. The San cause the stream to exceed the screening concentration of 0.33 mg/L more than Marcos River is home to the Texas Water Safari, one of the world’s largest canoe one time. The median total phosphorus concentrations were 0.06, 0.09 and races. The race attracts over 150 canoeing teams each June. Additionally, it was 0.10 mg/L, from upstream to downstream respectively, and ranged from below LQWKLVVHJPHQWWKDWWKH7H[DV3DUNVDQG:LOGOLIH'HSDUWPHQWRSHQHGWKHLUÀUVW WKHOLPLWRITXDQWLÀFDWLRQIRUWKHPHWKRGWRPJ/7KHFRQFHQWUDWLRQRIWRWDO Paddling Trail. The Luling Paddling Trail begins at the river crossing at SH 90 west SKRVSKRUXVH[FHHGHGWKHVFUHHQLQJFRQFHQWUDWLRQRIPJ/ÀYHWLPHVDWWKH of Luling and ends at the Zedler Mill in the city. The stream standard for contact TCEQ site. Again, the source of the nutrient may be coming from the wastewater recreation is a geometric mean of 126 organisms per 100 milliliters, and a single discharge that is within 3 miles of the sampling site. Other possible sources of the sample concentration of 394 organisms per 100 milliliters. The TCEQ monitored QXWULHQWVFDQEHIURPQRQSRLQWVRXUFHVVXFKDVVWRUPZDWHURIIRIIHUWLOL]HGÀHOGV for fecal coliform bacteria at their site before a contact recreation standard was established for E. coli. The geometric mean for fecal coliform in the small data set A review of the nutrient data for trends over time at the TCEQ site show statistically was 89 organisms per 100 milliliters (contact recreation standard for fecal coliform VLJQLÀFDQWGRZQZDUGWUHQGVLQWRWDONMHOGDKOQLWURJHQ 7.1 DQGWRWDOSKRVSKRUXV is a geometric mean of 200 organisms per 100 milliliters), and the geometric ÀJXUHVDQG 7.1LVDFRPELQDWLRQRIRUJDQLFQLWURJHQDQGDPPRQLDQLWURJHQ mean for E. coli was 101 organisms per 100 milliliter after the parameter was TKN and total phosphorus are both nutrients that are constituents of wastewater changed. Two samples exceeded the single sample standard of 400 organisms per 100 milliliters for fecal coliforms and exceeded the single sample standard for E. coli three times. At the GBRA Luling site, the geometric mean for E. coli was 55 organisms per 100 milliliters, exceeding the single sample standard 8 times. At the lower portion of the segment, the geometric mean for E. coli was 98 organisms per 100 milliliters, exceeding the single sample standard four times, all of which were GXULQJKLJKÁRZHYHQWV7KHKLJKHUFRQFHQWUDWLRQRIEDFWHULDDWKLJKÁRZVLVQRW unusual because storm water brings in bacteria and for a period of time after the VWRUPHYHQWWKHKLJKÁRZVNHHSVROLGVLQVXVSHQVLRQDQGVKDGHXOWUDYLROHWOLJKW from the sun from penetrating the water and killing the bacteria. Figure 4. Total Kjeldahl Nitrogen versus time at the San Marcos River at Old Bastrop Highway The land use in watershed that drains to the segment consists of mostly large   1RÁRZGDWDZDV farms and ranch land. The contributions of bacteria from agricultural activities that available for this data set). KDYHEHHQUHFRJQL]HGLQRWKHUSDUWVRIWKHVWDWHDVEHLQJDVLJQLÀFDQWVRXUFHRIWKH load in impaired streams are not seen in segment 1808 but this may be because WKHPHGLDQÁRZLQWKH6DQ0DUFRV5LYHUFDQDVVLPLODWHWKRVHFRQWULEXWLRQV%XWDV with other areas in the basin as well as the state, these family farms are being sold and subdivided, so you will begin to see more roof tops in the watershed than cattle, and those cattle in much more concentrated areas. With urban sprawl comes more impervious cover, more runoff and more pollutant loading.

A review of the data for suspended solidsDWHDFKORFDWLRQVKRZVQRVLJQLÀFDQW trend over time, or, if there was a slight trend, it was negative, i.e. a reduction in total suspended solids, over time. Looking at the segment as a whole, the median concentration of suspended solids increases as you move downstream, beginning Figure 5. Total Phosphorus at 8 mg/L at the uppermost site, going to 17.2 mg/L at the GBRA Luling site and versus time at the San Marcos River at Old Bastrop Highway then to 31.6 mg/L at the downstream site at SH 90A.   1RÁRZGDWDZDV available for this data set). The median chlorophyll a concentration is less than detection and there was never a measured value above the screening concentration of 14.1 microgram per liter. - 71 - 2008 Basin Summary Report