Center for Coastal Studies

Nueces River Tidal Segment Update for July 2026.

Monthly sampling in the Nueces River Tidal Segment occurred on July 21st. Weather conditions were the typical hot and sunny, with a moderate southeast breeze.

Last month's sampling event took place at the tail end of multiple flow events to the Nueces Tidal Segment from rain that occurred below Lake Corpus Christi. The segment received 5,276 acre-feet of inflows that resulted in fresh water at all stations in June.

No flow was recorded by the USGS for July 2026. Surface salinities started to creep up but were still on the low end of brackish with 6-7 ppt at all stations. Bottom salinities at the deepest station (NRT-02 at 5.3 meters) were around 12 ppt from 2.0-5.0 meters down.

NRT-01 had very low dissolved oxygen (1 mg/L and 13%). We saw mullet on the surface that were struggling with the lack of oxygen, but no dead fish were observed. Surface (0.3 m) oxygen levels were much better at the stations downstream. Stations 1-3 had elevated values of chlorophyll-a concentrations around 60 µmhos/cm (TCEQ screening limit is 21 µg/L). Bacteria levels were much lower this month at 20-40 CFU/100 mL

At stations 4 and 5, the oxygen levels were much higher and supersaturated (in excess of 100% oxygen) in the 10-11 mg/L range at the surface. Chlorophyll-a values were highly elevated (100-200 µg/L). Bacteria concentrations were 10 -31 CFU/100 mL at NRT-04 and NRT-05 respectively).

The final report for last year's sampling effort is online. Check it out from the link below.

https://www.cbbep.org/manager/wp-content/uploads/2536-Final-Report_Final.pdf

On my way to NYC for the NOAA CCME scholars meeting! I’m supporting Brenna Edwards, one of the scholars and a M.S. graduate student who is in our lab! She is presenting her research regarding feral swine impacts on wetland vegetation in South Texas wetlands. Go Brenna!

Center for Coastal Studies staff were out on the river last Tuesday (June 23rd) to get water quality data for the monthly nutrient and bacteria study funded by a grant through the Coastal Bend Bays and Estuaries Program. This month's sampling event took place at the tail end of multiple flow events sourced from runoff below Lake Corpus Christi. At the time of sampling, flow over the Calallen "saltwater barrier" Dam was 132 cfs and dropping.

Sampling data from the past 2 years were obtained during extreme drought conditions that saw very little water flowing over the saltwater dam. Tidal fluxes are very low in the segment. The result is very stagnant water that is susceptible to extreme stratification of the water column for salt, dissolved oxygen, temperature, and pH. Deeper water stations NRT-01 and NRT-02 typically had no available dissolved oxygen below 2.0 meters. Mean chlorophyll-a concentrations were typically between 3 and 6 times the screening limit (21 µg/L) indicating high nutrient loads are likely. Nutrient data also confirmed elevated levels of total nitrogen.

TPWD responded to a major fish kill in the segment in early May a week after the May sampling event. The segment needed a good flushing. Luckily the rains came and provided some major relief.

Here are the water quality data results. Nutrient data are still being processed and are not provided.

NRT-01 - Located below the saltwater barrier dam at Labonte Park
Water depth = 2.3 meters
No stratification was recorded
Salinity - 0.38 ppt at surface
Flow over saltwater = 132 cfs
Dissolved Oxygen = 5.4 mg/L and 71% oxygen
Chlorophyll = 2.8 µg/L (mean here are 59 µg/L)
Enterococcus bacteria = 380 MPN/100mL (104 MPN is the single day criteria/35 MPN is the mean criteria)

NRT-02 - Located at the first train crossing
Water depth = 5.3 meters
Salinity - 0.9 ppt at surface and 2.4 ppt at 5.0 meters
Some stratification was recorded
Dissolved Oxygen (0.3m) = 4.7mg/L and 61.9% oxygen saturation
Dissolved Oxygen (5.0m) = 3.2mg/L and 43.2% oxygen saturation
Chlorophyll = 5.4 µg/L (mean here are 69 µg/L)
Enterococcus bacteria = 583 MPN/100mL (104 MPN is the single day criteria/35 MPN is the mean criteria)

NRT-03 - Located at the terminus of Figuero Road
Water depth = 0.9 meters
Salinity - 1.02 ppt
Dissolved Oxygen (0.3m) = 5.0 mg/L and 66.9% oxygen saturation
Chlorophyll = 6.2 µg/L (mean here are 78 µg/L)
Enterococcus bacteria = 580 MPN/100mL (104 MPN is the single day criteria/35 MPN is the mean criteria)

NRT-04 - Located 1000m upstream of Allison WWTP outfall
Water depth = 1.3 meters
Salinity - 1.16 ppt
Dissolved Oxygen (0.3m) = 5.0 mg/L and 66.3% oxygen saturation
Chlorophyll = 6.9 µg/L (mean here are 129 µg/L)
Enterococcus bacteria = 230 MPN/100mL (104 MPN is the single day criteria/35 MPN is the mean criteria)

NRT-05 - Located upstream of 2nd railroad crossing
Water depth = 1.4 meters
Salinity - 1.14 ppt
Dissolved Oxygen (0.3m) = 4.7 mg/L and 62.1.% oxygen saturation
Chlorophyll = 6.9 µg/L (mean here are 129 µg/L)
Enterococcus bacteria = 280 MPN/100mL (104 MPN is the single day criteria/35 MPN is the mean criteria)

Repairs, maintenance and painting at our awesome LMFS - the best team!

Way to go Olivia! So proud of you and your work!

Marissa killed her second talk at SWS! She had a ton of questions and she handled them superbly!

M.S. student Marissa Spinelli just presented her art-science integration talk at the SWS meeting! Great job Marissa!