NBU says two power sources were unavailable and an alarm system failed before an estimated 550,000 gallons of untreated wastewater entered the Guadalupe River north of Lake Dunlap on May 27.
The discharge reached a river that NBU says supports New Braunfels residents’ quality of life, local businesses and tourism; the utility said its drinking-water system was not affected and downstream samples were at or below upstream levels.
The Rio Lift Station normally has two independent power sources from separate substations, NBU said. Lightning disabled one substation during the storm, while the other source was unavailable for planned maintenance. The utility said wastewater began discharging around 1 a.m. and stopped after power was restored around 4 a.m.
A backup battery was supposed to power the system that alerts NBU’s control center when electricity fails. NBU said the alarm did not work as intended, leaving crews without that immediate warning. Personnel investigating widespread storm outages discovered the overflow, according to the utility.
NBU said it began identifying critical facilities near environmentally sensitive areas, increasing backup-system testing and reviewing maintenance approvals, alarms, staffing and storm monitoring. Future testing results and corrective-action records can show how those safeguards perform after the spill.
Readers can inspect NBU’s May 27 notice and May 29 update for the utility’s timeline, sampling account and corrective measures. The next verification point is an NBU record reporting the results of its increased backup-system and alarm testing.