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Tens Of Thousands Of Fish Killed

July 29, 1985

DALLAS (AP) _ Tens of thousands of fish that died in the Trinity River may have suffocated after hard rains washed polluted sediment into the waterway and reduced oxygen levels, officials said.

By Monday, the weekend kill along a 75-mile stretch of river southeast of here appeared to be over, said Leland Roberts, chief of the state Department of Parks and Wildlife’s resource protection division.

″We suspect it may have been caused by urban and suburban runoff, which contains a variety of pollutants, said Roger Meacham, a spokesman for the Environmental Protection Agency. ″In addition to that, we suspect the rain may have stirred up contaminated river sediment.″

Sections of the river, which flows between Dallas and the Gulf of Mexico, looked like ″a river of dead fish,″ said Vic Palma, a state parks and wildlife investigator.

Heavy rains from July 19 to 22 may have caused sewers to overflow and wash polluted sediment into the river, officials said. Rainfall totaled only about 3 inches, but included several intense downpours, said Don Mankin, a National Weather Service meteorologist in Fort Worth.

″When you get periodic heavy rain that can stir up previously contaminated river sediment, and you combine that with suburban runoff, you get oxygen depletion,″ Meacham said.

Preliminary tests this weekend showed oxygen levels in parts of the river dropped to less than 1 milligram per liter of water, Palma said.

″That’s virtually a dead river,″ said Palma. ″That’s lower than I have ever seen in any water system.″

The river’s normal oxygen level is about 5 milligrams per liter. Fish generally need at least 2 milligrams of oxygen per liter of water to survive.

Most of the dead fish counted over the weekend were small-mouthed buffalo fish, Roberts said. A fish kill in the second week of July killed about 180,000 fish, most of them channel catfish.

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