To: Interested Parties
From: Environmental Services division
This is the Sabine River Authority Water Quality Summary for August 2002. Water quality sampling was performed August 13th through August 16th. Recent weather in the Basin was hot with air temperatures in the 90s during the daytime and lows in the 70s at night. Temperatures were a little cooler at the Orange weather station with highs mostly in the mid to upper 80’s. The Upper Basin received 1.67 – 1.75 inches of rainfall during the 28 days since the previous sample run as recorded at Lake Tawakoni and Lake Fork respectively. Almost all of the rain in the Upper Basin was recorded on the 28th day prior to the sample run. Toledo Bend received 2.57 inches during the 28 days preceding the sample run. Orange received heavy rainfall and flooding with 10.28 inches in the seven days prior to the sample run and a total of 11.50 inches in the 28 days prior to the sample run. Reservoir profiles indicated stratification of the water column with a distinct thermocline in each reservoir.
Upper Sabine Basin Above Toledo Bend Including Lake Fork and Lake Tawakoni
For the August sample run, most of the parameter's values seen at the Upper Basin sites were consistent with water of high quality. The most recent rain was 0.16 inches at Lake Tawakoni 19 days prior to the first sample date and 0.01 inches at Lake Fork six days prior to the sample date. Surface water temperatures were between 25.8 and 29.2C. One site, LF2, was below stream standards for dissolved oxygen. Other parameters for this site were normal, but the lower than expected dissolved oxygen could have resulted from an algal bloom. Although algal blooms cause increases in dissolved oxygen during the day, the blooms can lead to depressed oxygen levels at night. Five Upper Basin sites had over 100% saturation of dissolved oxygen, indicating mild algal bloom conditions. Two sites, BS18 and SR17, exceeded stream standards for E. coli. Surface temperatures near the dams at Lake Tawakoni and Lake Fork were 27.4 and 27.7C respectively. Bottom temperatures at the same sites were 21.4 and 18.2C respectively. Both reservoirs were thermally stratified.
Lower Sabine Basin Including Toledo Bend to Morgan Bluff
The August monthly sampling results were indicative of water of high quality at most sites. The last significant rainfall occurred five days prior to the sampling event, but some rainfall did occur on the second day of sampling. The level of Toledo Bend Reservoir was recorded around 168.9 feet with no discharge from the spillway gates at the time of sampling, although the generator was operating. All lake sites showed some stratification, but only the deepwater stations showed anoxic conditions at the deepest depths. Stations TB6N, TB8, TB6K and TB6M had oxygen levels that were below the stream standard, and station BA4 had a sulfate result that was above the stream standard.
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 at most sites. The area had heavy rain the day prior and the day of sampling. Stratification was found at the deepwater station SRT1. Surface salinities were found at station ICW1 with 2.4 ppt, and BB1 with 3.7 ppt. The highest salinity value of 11.2 ppt was recorded at station SRT1 at a depth of 10.6 meters. Station BB1 recorded a dissolved oxygen result that was lower than the stream standard. Station SR1 recorded an E. coli result that was above the stream standard. The runoff from the heavy rains in this area would most likely explain the high E. coli result. No bacteriological results were reported for the other tidal stations due to an incubator malfunction in the laboratory.
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:
Ø Upper Sabine Basin
John Payne, Upper Basin Field Office Coordinator
Ø Lower and Tidal Sabine Basin
Jerry Wiegreffe, Lower Basin Field Office Coordinator
If above are unavailable
Miles Hall, Assistant Division Manager Environmental Services
Printed Thursday, October 24, 2002