(KLST/KSAN)– When we’re experiencing drought conditions in the Concho Valley, it slows down the flow of the river. Lynn Wright with Inland Fisheries said so when it does rain, it throws off the oxygen levels causing a dissolved oxygen crash.

“We’re in drought conditions, there’s not a lot of flow in the river and when the river gets very stagnant there’s a lot of decomposing and if something disturbs it and kind of stirs it up,” Wright said. “We can see that decomposing and used up the rest of the oxygen in the water.”

Wright said this isn’t unusual, in fact we see this happen at least once or even twice a year, but never this early.

“A lot of times what we’ll see is when we get to the summer months, we have 100 degree days and a lot of rain, we go a long dry period then we get a heavy thunderstorm comes in it kind of stirs up the river we will usually see a fish kill, and that usually happens in July or August,” Wright said.

He said only a portion of the fish died as a result of the fish kill, so the fish will repopulate through natural reproduction.

“We’ve been through this before and the populations always bounce back,” Wright said.

Wright said catfish are restocked every two weeks through the neighborhood fishing program.

“The dead fish we saw died earlier in the week,” Wright said. “By the time Friday got around we were stocking catfish and the water quality was better, we even came back a few days later and measured again and the oxygen was still good, we even saw people out catching catfish, out fishing so that gave us a good indication that most of our fish survived.”

Wright said one common misconception when seeing fish kill in the river is that there’s pollution in the water. He said it’s important to know that’s not the case.

“We care about the river, we care about the fishery resource and we are doing everything we can to provide good fishing opportunities in San Angelo,” Wright said.