Sabine River Authority of Texas

Date: 7/29/99

To: Interested Parties

From: Environmental Services

RE: may 1999 Water Quality Monitoring Report

This is the Sabine River Authority Water Quality Report for May 1999. Water quality sampling was performed May 4 through May 5. The Upper Sabine Basin received heavier than normal rainfall, while the Lower Basin and Tidal Areas received more moderate amounts of rainfall. Warm and Windy condition prevail during the sample run. Due to failure of laboratory equipment values for ammonia, orthophosphate and total hardness were not obtained.

 

Upper Sabine Basin Above Toledo Bend Including Lake Fork and Lake Tawakoni

Most of the parameter's values seen at the Upper Basin sites are consistent with water of high quality. Temperature and dissolved oxygen profiles indicate several of the reservoir sites (LT23A and LF2) are beginning to thermally stratify, and upper-lake sites have become thermally stratified. Some noteworthy data points include low dissolved oxygen, low chlorophyll a, and elevated nitrate/nitrite near the dam at Lake Tawakoni (LT23A). There is no minimum stream standard for chlorophyll a but an unusually low value is indicative of reduced algal biomass, which, in turn, could cause the low dissolved oxygen (reduced photosynthetic production of oxygen) and elevated nitrate/nitrite (because the algae isnít present to convert nitrate/nitrite to algal proteins). LT23A also experienced low dissolved oxygen in 1998 during August, September (with associated elevated ammonia), and October (with associated elevated nitrate/nitrite), and in September of 1995 and 1996. On river sites, fecal coliform and streptococcus bacteria were high at BS18, SR17, SR16, SR15, and SR14. No numerical value was reported for SR14 due to confluent growth on the test plate and inability to differentiate individual colonies. SR11 also had elevated fecal coliform but wasnít as high as the other sites. The Texas Natural Resources Conservation Commission (TNRCC) was contacted and had not received any reports of wastewater bypasses that could have caused the high bacteriological counts. Generally, when both fecal coliform and streptococcus are elevated, it is indicative of non-human sources. Some areas in the watershed received heavy rains the previous day and are a likely cause for the elevated values, especially considering the high turbidity and low secchi depth values at the same sites. SR15 was especially muddy with a secchi depth of 0.15m and 305 NTU turbidity.

 

Lower Sabine Basin Including Toledo Bend to Morgan Bluff

Values measured during the May WQM were indicative of water with high quality. Stations TB6N, TB6I, TB6M, and TB6L had low dissolved oxygen values, these value were below stream standard spring time dissolved oxygen criteria. These criteria were established to protect fish spawning. Water samples taken at Station BA4 were unusually turbid. This is indicated by an elevated turbidity value (73.4 NTU) and a low secchi depth value (0.25 m). The Sulfate value was also elevated at this site. These values may be associated with a combination of runoff and land clearing activities. Lake Stations at Toledo Bend are beginning to show stratification of dissolved oxygen and temperature at depths of about 8 to 12 meters. This stratification is more evident for dissolved oxygen than for temperature.

 

Tidal Section of the Sabine Basin below Morgan Bluff

Values for stations in the tidal portion of the Sabine Basin were also consistent with water of high quality. None of the values measured in this area were outside of stream standard criteria. Salinity values were detected at three of the five stations in this area of the basin.

 

 

This Report and additional data for these monitoring stations are available on our World Wide Web site (www.sra.dst.tx.us). If you have any questions or comments concerning this report, please contact: