This Red River is not actual blood, but a bacterial sludge fed by dead fish and oil runoff pollution. Intense drought and heat lowered the San Angelo water so much that it became stagnant, unable to move. While the water evaporated, the pollution stayed behind, and the remaining muck was too toxic to support the fish. As they all died, their rotting corpses robbed the water of oxygen, which made it a perfect environment for the Rosy-faced Chromatiaceae bacteria.
So, although not actual blood, the San Angelo Reservoir is looking pretty scary. The worst part? These Red Rivers lead to a Red Lake, which actually provides DRINKING water for San Angelo and its surrounding communities in Tom Green County. I haven't heard of anyone turning on their tap and screaming bloody murder, so the drought must have kept this reservoir from reaching the pipelines. SO FAR. God only knows what will happen the next time a rainstorm hits Texas.