Low Oxygen After Rain Kills Fish in San Angelo’s Concho River

SAN ANGELO, TX — Heavy rain Thursday evening caused dissolved oxygen in the Concho River to plunge Friday morning, stressing and killing fish, Texas Parks and Wildlife Department officials said. 

The department’s Inland Fisheries San Angelo District measured 0.3 parts per million of dissolved oxygen above the Irving Street crossing. Fish begin to stress below 3 ppm and can die within a few hours when levels fall below 2 ppm. 

Stressed and dead fish were observed upstream as far as Central High School. Downstream from Irving Street, few stressed fish were seen. Oxygen measured 3.3 ppm at Celebration Bridge and 4.6 ppm at Bell Street. 

Low dissolved oxygen is common in the Concho River in late summer and can worsen when heavy rain suddenly stirs a hot, stagnant river, the district stated. 

Officials said levels should rise through the day as sunny skies increase photosynthesis and put more oxygen into the water.