They mention chlorine in the article but does Texas have chlorine or chloramine in the water supply?
Either way a large amount of chlorinated water will wipe out fish in rivers, creeks or ponds. That is why you need to dechlorinate new water before adding it to the tank.
Some years ago one of the mining companies in New Guinea hit a natural gas pocket and damaged the soil above it. The gas seeped into Lake Kutubu and wiped out tens of thousands of fish including Melanotaenia lacustris. The locals who live by the lake needed food drops for the next 12 months while the fish stocks built back up.
Good ol humans, screwing up everything wherever they go