Sabine River Authority of Texas

To: Interested Parties

From: Environmental Services

RE: June 1999 Water Quality Monitoring Report

This is the Sabine River Authority Water Quality Report for June 1999. Water quality sampling was performed June 15 through June 16. The Sabine Basin received greater than average rainfall at all locations except Lake Fork. River flows were high for this time of year throughout the Basin. Warm and windy conditions prevailed during the sample run. Due to failure of laboratory equipment, values for ammonia, orthophosphate, total alkalinity and total hardness were not obtained. Also, nitrite and nitrate were measured only at a few sites.

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

Most values measured in the Upper Basin were consistent with water of high quality. Temperature and dissolved oxygen profiles indicate most of the reservoir sites were thermally stratified. At Lake Fork, LF2 was thermally stratified between eight and nine meters, LF3 between four and five meters, and LF4 between six and seven meters. The pH exceeded Texas Surface Water Quality Standards (Stream Standards1) at LF2. Lake Tawakoni was thermally stratified only at LT23C. There was only one degree of difference in temperature from surface to bottom at LT23A and LT23D and dissolved oxygen increased from around 4mg/L near the bottom to about 8mg/L at the surface for these two sites. The pH exceeded Stream Standards at LT23A and LT23D. Some noteworthy data points on the river included a nitrate/nitrite value which exceeded TNRCC screening criteria at LF20 (which also had elevated conductivity, sulfate, and chlorides) and low dissolved oxygen values in the Sabine River from Gladewater to Longview (SR17, SR16, SR15, and SR14). USGS river flow data and high secchi disk depths indicate the May rainfall releases from Lake Fork and/or Lake Tawakoni were peaking in the Gladewater/Longview region of the river during the WQM. However, this does not explain the low dissolved oxygen values.

Lower Sabine Basin Including Toledo Bend to Morgan Bluff

Values measured during the June WQM were indicative of water with high quality. Stations TB6N and TB6M had dissolved oxygen values below the numerical criteria for Stream Standards. Dissolved oxygen values at Stations TB6A, TB6, and SR5 were rejected because the dissolved oxygen meter failed its quality assurance check. Station BA4 had elevated values for turbidity, conductivity, fecal coliform and fecal streptococcus. Sample sites TB6N, SR3, BCC1 and SR2 had elevated turbidity values. Stations SR2 and BCC1 also had elevated fecal coliform values. These elevated values were most likely due to a heavy rainfall event just prior to the June sampling. Lake stations at Toledo Bend showed stratification of temperature and dissolved oxygen at depths from 3 to 8 meters.

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. All values were within the Stream Standard criteria and TNRCC screening criteria. Salinity values were detected at two of the five stations in this area of the Basin. Releases from Toledo Bend along with the rainfall just prior to the sampling were most likely the reason for the low salinity.

 

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:

 

1 The TNRCC sets surface water quality standards in an effort to maintain the quality of water in the state. This document is currently under revision and can be found at the following URL. http://www.tnrcc.state.tx.us/water/quality/standards/index.html

Printed Wednesday, February 23, 2000