Upper Nueces River Water Quality Update — September 24, 2025

Overview

To complement recent measurements taken on the lower Nueces River near Calallen, the Nueces Groundwater Conservation District collected comparative readings farther upstream near Knolle Dairy Farms in Sandia, Texas. These upstream measurements help establish a baseline closer to the dam to better understand how salinity and total dissolved solids (TDS) change along the river.

Field Reading (Knolle Dairy Farms – Sandia, TX)

Location: Nueces River at Knolle Dairy Farms, Sandia, TX
Time: 12:56 PM
Date: September 24, 2025
Salinity: 0.6 ppt
TDS: 798 mg/L
Temperature: 85.5°F
Instrument: YSI Pro30 Water Quality Meter

For transparency, the YSI Pro30 meter is factory-set to display TDS as specific conductance multiplied by 0.65, a standard conversion used in water quality monitoring.

USGS Monitoring Station Comparison — Nueces River at Bluntzer (TX-08211200)

Date/Time: September 24, 2025 – 4:00 PM CDT
Specific Conductance: 1320 µS/cm (@ 25°C) ≈ 858 mg/L TDS
pH: 8.2
Dissolved Oxygen: 7.9 mg/L

These readings indicate stable conditions in the upper Nueces River, showing fresh to slightly brackish water with balanced dissolved oxygen and neutral pH—typical for late-summer flow conditions in the region.

Why This Matters

Monitoring water quality along the Nueces River helps identify natural variations and seasonal changes that can influence groundwater recharge and salinity movement. Collecting data at multiple locations—from the upper river near Sandia to downstream areas near Calallen—provides a more complete understanding of how surface water interacts with regional aquifers and supports sustainable management of local resources.