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Comination of algae and rainstorm apparently caused Alameda Creek fish kill

The Alameda County Water District has tentatively concluded that this month’s fish kill at Alameda Creek was likely caused by a combinationof algae, and run-off from the first rain storm of the season, tts General Manager Paul Piraino said.

Algae draws oxygen out of the water when the sun goes down, and the first storm brought a lot of cloudy, poorly oxygenated water with additional oxygen-sucking organic materials into the creek, Piraino said. The combination apparently caused levels of dissolved oxygen to plunge and led to about 5,000 fish dying in the creek on Oct. 6.

 The conclusions were reached by a panel of experts in urban run-off, fishery and stream beds, Piraino said.

The Water District has drained the affectedpool over the past few days to kill the algae in advance of this weekend’s storm. He doesn’t expect the rains to cause a second fish kill.

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Up to 5,000 fish dead in Alameda Creek

Investigators are still trying to determine what led to a major fish kill in Fremont this weekend. Between 3,000 and 5,000 fish were found dead in a segment of Alameda Creek between Mission Boulevard and the train overpass in Niles.

The fish apparently died due to lack of oxygen in the water, but investigators are still trying to determine why the oxygen levels had decreased, said Paul Piraino of the Alameda County Water District. Possible explanations are runoff from the first storm of the season Friday night or a pipe failure at Dublin San Ramon Services district which resulted in a discharge that flowed into Alameda Creek.

Tests should be completed on Thursday.