*An earlier version of this article included an incorrect measure of the amount of water used to fight the fire on Business Loop 70.
COLUMBIA — The results are in from water samples taken after the recent fish kill in Flat Branch, linking the death of more than 14,000 fish to an April 1 strip mall fire — the cause of which a city fire marshal said he doubts will be determined.
Petrochemicals found in the creek during an investigation into the cause of the fish kill likely contributed to elevated levels of gasoline, waste oils and other chemicals found in samples taken the day after the fire, according to a 12-page document compiled by the Missouri Department of Natural Resources. The chemicals have been linked to contaminated runoff from the more than 1 million gallons* of water used on the blaze that engulfed O'Reilly Auto Parts and several other Business Loop 70 storefronts. That water then drained into the creek, which is fed by numerous storm drains in downtown Columbia, according to a previous Missourian report.
An estimated 14,749 fish, valued at $4,614, were killed, said Jim Low, a spokesman for the Missouri Department of Conservation. Fish and crawfish were wiped out from Flat Branch Park to Bridge No. 8 on the MKT Nature and Fitness Trail, he said, adding that the the largest number of live fish were found at the confluence of Hinkson Creek and Flat Branch, where fish enter the Flat Branch stream.
Low oxygen levels most likely cause
Renee Bungart, a spokeswoman for the Department of Natural Resources, said her agency concluded that low oxygen levels were the most likely cause of the fish kill.
Low levels of oxygen were the result of a high carbon demand, said Jack Jones, an MU professor who studies aquatic ecology. When carbon-based products — such as the oil, paint and antifreeze housed in the auto supply store — entered the runoff incompletely combusted, the bacteria that decompose it use oxygen and create carbon dioxide, similar to the way humans breathe.
Oxygen levels in the creek returned to about normal by April 6, Low said.
Samples from the creek were tested for 105 different values that included pH, dissolved oxygen, temperature, turbidity, 13 petrochemicals, 82 volatile organic acids and nutrients such as nitrogen, phosphorus and nitrates.
The highest levels of chemical contaminants were 6.64 parts per million of waste oil at Flat Branch Park and 1.5 parts per million of gasoline at Martin Luther King Jr. Memorial at Battle Garden Park. These contaminants were measured as total petrochemical hydrocarbons, a mixture of compounds that make up petrochemicals.
"I'm sure these recent rains have washed the rest of carbonaceous matter downstream," Jones said, referring to this past weekend, and that "the high water has dissipated most everything."
Aquatic life could also have been harmed by other chemicals found in the water used to put out the fire, which contained chlorine and chloramines used to treat water and make it drinkable. In recent years, more utilities have begun to use chloramines — derivatives of ammonia — as a secondary disinfectant for drinking water as it moves through pipes, according to the Environmental Protection Agency. Columbia started adding ammonia to its water in September 2009, said Floyd Turner, manager of the city's water operations. Public outcry led the EPA to create a site answering commonly asked questions about the use of chloramines.
Battalion Chief Steven Sapp of the Columbia Fire Department said Tuesday that investigators believe the fire started in the north end of the building that houses O'Reilly's Auto Parts and Adam's Barbershop. Sapp said he was doubtful a cause can be determined because of the extent of damage.
Sapp said he'll be meeting with insurance representatives Friday to continue investigating the fire, at which point damage estimates will be updated. Early damage estimates were $2.5 million for the structure and $4 million for inventory.
Bungart said the Department of Natural Resources does not plan to take any enforcement action at this time.