Sabine River Authority of Texas

To: Interested Parties

From: Environmental Services

RE: August 1999 Water Quality Monitoring Report

This is the Sabine River Authority Water Quality Report for August 1999. Water quality sampling was performed August 10 through August 12. Warm and dry conditions prevailed throughout the Basin in August. Due to failure of laboratory equipment values for ammonia and orthophosphate were not obtained

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

Most parameters measured in the Upper Basin were consistent with water of high quality. The 30 days prior to sampling were dry with only about 0.3in of rainfall in the region. Temperature and dissolved oxygen profiles indicate most of the reservoir sites were thermally stratified. Lake Fork sites were strongly stratified at about 7m with 4.5 - 14.8C of difference from surface to bottom. Lake Tawakoni sites were weakly stratified at 3-6m with 1.9-2.3C of difference. LT23C is the shallowest site at 4.3m and wasn't stratified, having only 0.5 C of difference from surface to bottom. High algal photosynthetic activity (note chlorophyll a levels) at both reservoirs caused elevated dissolved oxygen values at several sites. The pH at all three Lake Tawakoni sites exceeded Texas Surface Water Quality Standards (Stream Standards1). Data at river sites reflected the dry weather and low flow conditions. Dissolved oxygen was slightly below Stream Standards at BS18, SR16, and SR14 and water temperature was 32.4C at SR19, exceeding Stream Standards by 0.2C. Fecal coliform bacteria were low at all sites due to absence of recent rainfall runoff.

Lower Sabine Basin Including Toledo Bend to Morgan Bluff

August WQM sampling results were indicative of water of high quality at most sites. Toledo Bend Reservoir levels were low due to an usually dry summer. Prolific growths of submerged, emergent and floating aquatic plants further impacted certain water quality parameters measured. Stations TB6N, TB6I, TB6M, and TB6 had dissolved oxygen values that were below Stream Standards. Deep water stations sampled at Toledo Bend Reservoir exhibited thermal stratification at about 8m. This thermal stratification caused nearly anoxic conditions in the lower profiles. Compared to other sites sampled during the August WQM, Station BA4 had higher values for the following parameters: conductivity, TOC, chloride, and sulfate. Station BA4 is sampled downstream from a paper mill discharge. At the time this sample was taken, the bayou was lower than normal with very dark, almost black water that had an odor similar to sewage. Also, Station TB6N, sampled below a WWTP discharge, had elevated values for the following parameters: conductivity, TOC, chloride, and sulfate. This site, was stagnant, almost completely covered with floating aquatics and had an oily, organic sheen apparent on the surface.

Tidal Section of the Sabine Basin below Morgan Bluff

Stations sampled in the tidal portion of the Sabine Basin had values that were consistent with water of high quality. All values measured were within Stream Standards criteria. Salinity values were detected at three stations during the August WQM. Station ICW1 had a salinity value of 2 ppt; Station BB1 and Station SRT1 had salinity values of 6 ppt. The deepest profile reading taken at Station SRT1 had a salinity value of 8 ppt. There was an incoming tide while monitoring these sites. However, no discernable saltwater wedge was detected.

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