February 13th, 2026

Recent news articles have discussed arsenic levels in the Nueces River raw water source. Arsenic is a naturally occurring semi-metal element that can dissolve into groundwater from surrounding rock formations. It has been present in the Nueces River surface water for many years, but concentrations remained below the Maximum Contaminant Level (MCL) established by the Texas Commission on Environmental Quality (TCEQ). Over the last two years, increases in arsenic have been documented bordering & sometimes slightly exceeding the MCL of 0.01 mg/L (aka ppm).

One of the first steps in the water treatment process used by San Pat Water is sedimentation. This step settles out heavy particles – including arsenic – prior to the water being filtered.

San Patricio Municipal Water District has historically followed the EPA/TCEQ rules of monitoring for arsenic annually, and our numbers have always been below the MCL:

• 2023 = 0.0029 mg/L
• 2024 = 0.0040 mg/L
• 2025 = 0.0036 mg/L

However, in light of recent concerns, we are in the process of increasing our testing for arsenic in both our incoming raw water and our finished drinking water. The increased monitoring helps verify that arsenic levels remain well within regulatory limits and supports the District’s commitment to providing high-quality drinking water.