*An earlier version of this article included an incorrect quote from Rebecca O'Hearn, a resource scientist at the Conservation Department. **It also included an incorrect measure of the amount of water used to fight the fire.
COLUMBIA — During the five years that Derrick Fogle has commuted to work on the MKT Nature and Fitness Trail, he's developed an understanding of the habits and life cycles of its inhabitants, cultivating a deep connection with the nature he whizzes past on his bicycle each day.
After pollution from an April fire at an auto supply store and other businesses contributed to a kill of an estimated 14,749 fish in Flat Branch, he wasn't sure when he would see the creatures he had come to expect on his daily work route begin to recover.
"It didn't occur to me at all when I heard about the fire that there would be any damage to the creek," he said. "But the day after, I got down to the trail, and there were no signs of life in the creek anywhere — that smell, that burnt chemical stink really hung around for several weeks."
Eight months after all aquatic life was wiped out in a stretch of Flat Branch, researchers with the Missouri Department of Conservation say the stream is showing a remarkable recovery. Scientists documented an increase in several species of fish and macroinvertebrates in a mid-October sample.
The fire started in O'Reilly Auto Parts and spread to several other businesses, causing more than $6.5 million in damage. According to a previous Missourian report, more than 1 million gallons* of water used to extinguish the fire washed into Flat Branch through storm drains, killing fish and other aquatic life from Flat Branch Park to Bridge No. 8 on the MKT. Investigators said they will not be able to determine the cause of the fire.
Fogle, an administrator at MU's Academic Support Center, has posted numerous reader comments at ColumbiaMissourian.com about the impact of the fire on the stream and its recovery. Starting in the summer, he began to notice the stream was making a comeback, starting with a snapping turtle he had seen in the same place for the past three years. (See some of Fogle's photos of Flat Branch here.)
"There's a huge mulberry tree and every spring the snapping turtle comes to eat the berries," he said. "It took him a lot longer to come out this year — the tree was already dropping its fruit. I was really worried he wasn't going to come back, but those snapping turtles are tough."
He saw the turtle for the first time after the fire on May 19, and noticed crawfish on June 26 and a variety of fish shortly after.
"From my perspective, by the end of the summer, you'd be really hard-pressed to tell anything had happened to that creek, and by September, the creek really was as normal as I'd ever seen it," he said.
Researcher Matt Combs has been following the creek's progress since the day of the fire, and said the Conservation Department will continue to monitor and document the recovery of the fish and macroinvertebrates by taking one sample per season for at least the next two years.
"We don't have any samples from before the fire event to see how much recovery there has been, but recent samples show there are more fish species in Flat Branch now than there were in April," he said. "Usually when a community like this recovers, it starts at very close to zero species and at some point the species level off and do not increase anymore, so that's what we'll be looking for."
Rebecca O'Hearn, a resource scientist at the Conservation Department, said the kill could have been caused by a variety of factors, but low oxygen was likely the culprit.
"We did measure low dissolved oxygen during and after the fish kill, and although we can't determine the direct cause of the kill, we can say low oxygen did have an effect," she said.
The Missouri Department of Natural Resources took samples from the creek the day of the fire and found elevated levels of gasoline, waste oils and other chemicals, which likely caused the oxygen depletion.
Because Columbia storm drains empty into Flat Branch, efforts to put out fires can have detrimental effects on the balance of the ecosystem. O'Hearn said there are not many ways to prevent this.
*"Sometimes they can use a dechlorination unit when extinguishing a fire, but it's not really possible when it was as large as this one was," she said.
There are several ways to address pollution events like the one caused by the fire. "You can actively try to do some restoration measures, or you can let it naturally recover — we’re letting it naturally recover in this case," O'Hearn said.
A sample taken in October shows recovery in benthic invertebrates such as crawfish and dragonfly larvae, as well as in numerous fish populations, including the central stoneroller, the creek chub, the orangethroat darter and the bluntnose minnow. They are still awaiting recovery of other species, including the golden redhorse, slender madtom, johnny darter and yellow bullhead.
"It's hard to say what's typical, but we are pretty surprised at how rapidly the species are recovering," O'Hearn said. "Benthic invertebrates are pretty mobile, so you see them recovering quickly if there’s no residual toxicity in the environment."
O'Hearn said the fish recovery may be attributed to migratory populations coming upstream from Hinkson Creek and from small tributaries that feed into Flat Branch.
"We aren't monitoring any populations in the side channels that feed into the creek to prove that's where they're originating from, but there's a lot of literature that proves that is common after a kill like this," she said.
Fogle said though he has seen a big recovery since April, he has noticed some populations affected by other pollution since the fire. It's just part of the cycle of a creek that's situated in an urban watershed, he said.
"Life comes and goes, and this isn't the first time there's been kills on that creek — not by a long shot," he said. "It would take a monumental effort to clean up the entire downtown area to be able to really bring that creek back to health."