Sabine River Authority of Texas

To: Interested Parties

From: Environmental Services division

RE: july 2002 monthly Water Quality Report

This is the Sabine River Authority Water Quality Summary for July 2002. Water quality sampling was performed July 9th through July 11th. Recent weather in the Basin was hot with air temperatures in the 90s during the daytime and lows in the 70s at night. The Upper Basin received 3.13 3.34 inches of rainfall during the 28 days since the previous sample run as recorded at Lake Tawakoni and Lake Fork respectively. Toledo Bend and Orange received 3.11 and 5.90 inches respectively during the 28 days preceding the sample run. Reservoir profiles indicated stratification of the water column with a distinct thermocline in each reservoir. Samples were taken at all sites for total and dissolved metals in water, and sediment samples were collected at selected sites. Data for metals will be available at a later date pending completion of laboratory analyses.

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

For the July 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 0.34 inches at Lake Tawakoni and 0.60 inches at Lake Fork six days prior to the first sample date. Surface water temperatures were between 26.5 and 31.5 C. All sites met stream standards for E. coli. Four reservoir sites exceeded stream standards for pH. These sites also had elevated chlorophyll a and had high dissolved oxygen. Elevated chlorophyll a with high dissolved oxygen indicates algal bloom conditions and this combination may lead to elevated pH levels. Algal blooms may be caused by natural conditions or by anthropogenic addition of nitrogen compounds, usually by runoff from fertilized lawns or agricultural operations. Sites on both Lake Fork and Lake Tawakoni had algal blooms and did not have significant levels of available nitrate/nitrite or orthophosphate. The algal bloom and resulting high pH levels are attributed to natural conditions of high water temperature and good water clarity. Surface temperatures near the dams at Lake Tawakoni and Lake Fork were 27.8 and 29.1 C respectively. Bottom temperatures at the same sites were 14.1 and 20.6 C respectively. Both reservoirs were thermally stratified.


Lower Sabine Basin Including Toledo Bend to Morgan Bluff

The July monthly sampling results were indicative of water of high quality at most sites. The last significant rainfall occurred over seven days prior to the sampling event. The level of Toledo Bend Reservoir was recorded around 171 feet with no discharge from the spillway gates at the time of sampling, although the generator was operating (July 2002 Generating Schedule: Unit 1 only, 13 hours/day, Monday Saturday, 10:00 AM 11:00 P.M; Unit 2 was in a planned outage due to renovation). All lake sites were well stratified with all of the stations showing anoxic conditions at the deepest depths. Stations TB6N and TB6M had oxygen levels that were below the stream standard and station BA4 had a sulfate result that was above the stream standard. Station TB6K also had a pH value that was just slightly 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 only a slight amount of rain in the week prior to sampling. All sites were stratified with respect to dissolved oxygen, but all sites were well mixed with respect to temperature. Surface salinities were found at all but one of the four tidal stations. Station ICW1 recorded a value of 2 ppt, BB1 had a value of 4 ppt, and SRT1 had a value of 4 ppt at the surface. The highest salinity value of 9 ppt was recorded at station SRT1 at a depth of 9 meters. All values recorded in this section of the Basin were within their stream standard.

 

 

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:

 

       Upper Sabine Basin
John Payne, Upper Basin Field Office Coordinator
903-878-2420 (jpayne@sra.dst.tx.us)

       Lower and Tidal Sabine Basin
Jerry Wiegreffe, Lower Basin Field Office Coordinator
409-746-3284 (jwiegreffe@sra.dst.tx.us)

       If above are unavailable
Miles Hall, Assistant Division Manager Environmental Services
409-746-2192 (mhall@sra.dst.tx.us)

 

Printed Thursday, September 19, 2002