Water Quality Index

Recent Water Quality Conditions

​​​​The Water Quality Index (WQI) is based on whether water quality data meets Texas Surface Water Quality Standards. The standards are written by the Texas Commission on Environmental Quality, with guidance provided by the U.S. Environmental Protection Agency and under the authority of the federal Clean Water Act and Texas Water Code. The standards generally consider three water uses: aquatic life, recreation and domestic water supply.

The list of parameters used to produce the WQI include: dissolved oxygen, pH, temperature, E. coli bacteria and total dissolved solids calculated from specific conductivity. Data are provided by Colorado River Watch Network volunteers and LCRA staff.

Important points about the WQI:

  • This is not a swimming index. Regardless of whether the standard was met, there is always a chance that microbes in the water may cause infections. Swimming in any river, lake or pond carries some risk. Be aware of inherent risks and take appropriate precautions at all times.
  • Data used for the WQI are representative of conditions at the time samples were collected. Conditions may have changed by the time samples were analyzed and results were reported. Rainfall runoff, for example, will affect WQI parameters.

San Saba River at State Hwy 16

Date collected: 11/8/2017
Parameters Texas Surface Water Quality Standard Reported Data
Bacteria (E. coli #/100mL)
< 126 N/A
Dissolved Oxygen (mg/L)
> 5.0 6.3
Temperature (F)
< 90 62.6
Total Dissolved Solids (mg/L)
< 425 335
pH (standard units)
6.5 - 9.0 7.3

Lake Buchanan at the Dam

Date collected: 10/9/2017
Parameters Texas Surface Water Quality Standard Reported Data
Bacteria (E. coli #/100mL)
< 126 < 1
Dissolved Oxygen (mg/L)
> 5.0 7.6
Temperature (F)
< 90 77.4
Total Dissolved Solids (mg/L)
< 600 231
pH (standard units)
6.5 - 9.0 8.4

Llano River at Robinson Park

Date collected: 12/5/2017
Parameters Texas Surface Water Quality Standard Reported Data
Bacteria (E. coli #/100mL)
< 126 N/A
Dissolved Oxygen (mg/L)
> 5.0 7.5
Temperature (F)
< 91 55.4
Total Dissolved Solids (mg/L)
< 350 196
pH (standard units)
6.5 - 9.0 7.0

Inks Lake at Inks Lake State Park Store

Date collected: 11/8/2017
Parameters Texas Surface Water Quality Standard Reported Data
Bacteria (E. coli #/100mL)
< 126 50
Dissolved Oxygen (mg/L)
> 5.0 6.6
Temperature (F)
< 90 66.2
Total Dissolved Solids (mg/L)
< 600 228
pH (standard units)
6.5 - 9.0 8.0

Lake LBJ at the Dam

Date collected: 11/24/2017
Parameters Texas Surface Water Quality Standard Reported Data
​Bacteria (E. coli #/100mL)
< 126 80
Dissolved Oxygen (mg/L)
> 5.0 7.6
Temperature (F)
< 94 82.4
Total Dissolved Solids (mg/L)
< 500 221
pH (standard units)
6.5 - 9.0 N/A


Lake Marble Falls at Lakeside Park

Date Collected: 11/10/2017
Parameters Texas Surface Water Quality Standard Reported Data
Bacteria (E. coli #/100mL)
< 126 N/A
Dissolved Oxygen (mg/L)
> 5.0 6.8
Temperature (F)
< 94 66.2
Total Dissolved Solids (mg/L)
< 500 10
pH (standard units)
6.5 - 9.0 7.5

Pedernales River at Hammetts Crossing

Date collected: 11/28/2017
Param​eters Texas Surface Water Quality Standard Reported Data
Bacteria (E. coli #/100mL)
< 126 0
Dissolved Oxygen (mg/L)
> 5.0 8.0
Temperature (F)
< 91 61.7
Total Dissolved Solids (mg/L)
< 525 302
pH (standard units)
6.5 - 9.0 7.0

Lake Travis at Mansfield Dam Park

Date collected: 11/30/2017
Parameters Texas Surface Water Quality Standard Reported Data
​Bacteria (E. coli #/100mL)
< 126 0
Dissolved Oxygen (mg/L)
> 6.0 6.3
Temperature (F)
< 90 65.3
Total Dissolved Solids (mg/L)
< 400 221
pH (standard units)
6.5 - 9.0 7.5

Colorado River at Hwy 183 in Austin

Date collected: 11/27/2017
Parameters Texas Surface Water Quality Standard Reported Data
Bacteria (E. coli #/100mL)
< 126 N/A
Dissolved Oxygen (mg/L)
>6.0* 8.2
Temperature (F)
< 95 59.0
Total Dissolved Solids (mg/L)
< 500 336
pH (standard units)
6.5 - 9.0 7.7

*Dissolved oxygen criterion of 6.0 mg/L only applies at streamflows greater than or equal to 150 cubic feet/second (cfs) as measured at the U.S. Geological Survey gauge upstream from U.S. Highway 183. A dissolved oxygen criterion of 5.0 mg/L applies to streamflows less than 150 cfs.


Colorado River at Lost Pines Nature Trails Bastrop

Date collected: 12/1/2017
Parameters Texas Surface Water Quality Standard Reported Data
Bacteria (E. coli #/100mL)
< 126 20
Dissolved Oxygen (mg/L)
> 6.0 9.5
Temperature (F)
< 95 67.1
Total Dissolved Solids (mg/L)
< 500 376
pH (standard units)
6.5 - 9.0 8.5

Colorado River at Smithville

Date collected: 10/2/2017
Parameters Texas Surface Water Quality Standard Reported Data
​Bacteria (E. coli #/100mL)
< 126 135
Dissolved Oxygen (mg/L)
>6.0 6.5
Temperature (F)
< 95 78.6
Total Dissolved Solids (mg/L)
< 500 286
pH (standard units)
6.5 - 9.0 7.8

Colorado River at Bus Hwy 71 La Grange

Date collected: 11/28/2017
Parameters Texas Surface Water Quality Standard Reported Data
Bacteria (E. coli #/100mL)
< 126 N/A
Dissolved Oxygen (mg/L)
> 5.0 8.2
Temperature (F)
< 95 64.4
Total Dissolved Solids (mg/L)
< 500 406
pH (standard units)
6.5 - 9.0 8.0

Colorado River at Beason's Park Columbus

Date collected: 11/19/2017
Parameters Texas Surface Water Quality Standard Reported Data
Bacteria (E. coli #/100mL)
< 126 0
Dissolved Oxygen (mg/L)
> 5.0 8.6
Temperature (F)
< 95 65.3
Total Dissolved Solids (mg/L)
< 500 422
pH (standard units)
6.5 - 9.0 8.0

Colorado River at Wharton

Date collected: 10/2/2017
Parameters Texas Surface Water Quality Standard Reported Data
Bacteria (E. coli #/100mL)
< 126 31
Dissolved Oxygen (mg/L)
> 5.0 8.3
Temperature (F)
< 95 84.2
Total Dissolved Solids (mg/L)
< 500 397
pH (standard units)
6.5 - 9.0 8.2

Colorado River at Matagorda County Birding Nature Center Bay City

Date collected: 11/26/2017
Parameters Texas Surface Water Quality Standard Reported Data
Bacteria (E. coli #/100mL)
< 126 0
Dissolved Oxygen (mg/L)
> 5.0 8.6
Temperature (F)
< 95 66.2
Total Dissolved Solids (mg/L)
< 500 398
pH (standard units)
6.5 - 9.0 8.0

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