To: Interested Parties
From: Environmental Services division
This is the Sabine River Authority Water Quality Summary for March 2001. Water quality sampling was performed March 12th through February 14th. The Upper Basin received 12.63-11.20 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 8.04 and 2.83 inches respectively during the 28 days preceding the sample run. Daytime temperatures were in the 60's and 70's throughout the Basin and lows were mostly in the 40's. Some parameters were influenced by heavy rains prior to the sample run. Temperature and dissolved oxygen profiles indicate the reservoirs have weak vertical stratification at deeper sites.
Upper Sabine Basin Above Toledo Bend Including Lake Fork and Lake Tawakoni
For the March sample run, most of the parameter's values seen at the Upper Basin sites were consistent with water of high quality. A heavy rainfall in excess of two inches two days prior to the sample run in the Upper Basin created some unusual conditions in Lake Tawakoni, Lake Fork, and in the river downstream. The reservoirs were unusually muddy; turbidity, and nutrients were elevated. Due to flushing of water from Lake Tawakoni and Lake Fork, the river downstream was flooded and unusually clear. Bacteriological counts were at or above stream standards at upper arm reservoir sites on both reservoirs but within standards at lower reservoir sites near the dams. High bacteriological counts are not unusual after a significant rain but the effects aren't usually as significant in the reservoirs where there is a large dilution factor on rainfall runoff. Orthophosphate and turbidity followed the same trend with higher levels than normal recorded in the upstream arms of Tawakoni and Fork. Sites near the dams (LT23A and LF2) were normal. Ammonia was elevated at LT23A and LF3. Stream standards do not exist for nitrogen and phosphorus compounds so statewide screening criteria are used for comparison. Lake Fork and Lake Tawakoni reservoirs were technically mixed with no distinct zone of vertical stratification but some dissolved oxygen and temperature gradients are beginning to appear. Three stream/river sites (HRS16, BS18, and SR22) had elevated fecal coliform counts. Streptococcal counts done at HRS16 and SR22 indicate sources are likely non-human. Most river sites were unusually clear with the large volume of water flushed from the reservoirs. Secchi and turbidity values seen at river sites were more typical of what is normally seen at Lake Fork.
Lower Sabine Basin Including Toledo Bend to Morgan Bluff
March WQM sampling results were indicative of water of high quality at most sites. Toledo Bend Reservoir was above pool level at the time samples were taken. Deep-water stations sampled on the reservoir exhibited thermal stratification. Stations TNH01, TB6N, BA4, and BCC1 had levels of fecal coliform above stream standards. Orthophosphate was above suggested screening criteria at TNH01. Recent heavy rains and increased runoff from the surrounding watershed are the most probable factors in the increase in bacteria colony counts.
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. Salinity was not detected at any tidal site due to a great influx of fresh water from recent rains. Deep-water stations sampled did exhibit thermal stratification but did not show a salt-water wedge. Stations AB7, AB2, and CB4 had levels of fecal coliform above stream standards. Higher bacteriological counts are not an unusual occurrence when combined with heavy runoff and increasing temperatures.
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
Cynthia Darbonne, Lower Basin Field Office Coordinator
If above are unavailable
Miles Hall, Environmental Services Assistant Division Manager
Printed Tuesday, May 08, 2001