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Jan 9, 2015

04:26:05 GMT--Biological Hazard - North-America - USA

EDIS Number: BH-20141231-46506-USA

Date / time: 31/12/2014 05:25:51 [UTC]

Event: Biological Hazard

Area: North-America

Country: USA

State/County: State of Nevada

Location: Sparks [Sparks Marina]

Number of Deads: N/A

Number of Injured: N/A

Number of Infected: N/A

Number of Missing: N/A

Number of Affected: N/A

Number of Evacuated: N/A

Damage level: N/A


Fish are once again dying at Sparks Marina due to depleted oxygen levels in its waters. One year after plummeting oxygen killed all of the marina's fish, a similar but thus-far much smaller event appears to be occurring, officials with the Nevada Department of Wildlife and the city of Sparks report. About 100 dead trout were found along the shoreline of the urban lake between Saturday and Monday, with another 100 to 200 discovered Tuesday morning, said Sparks spokesman Adam Mayberry. "It certainly appears to be happening again," Mayberry said. "It doesn't seem as violent as it did last year." In mid-December 2013, officials first estimated that about 3,000 fish died from low oxygen levels in one corner of the 77-acre lake. Weeks later after tests found virtually no dissolved oxygen in the lake's waters and an electronic fish-finder was unable to locate any fish swimming in the lake's depths, Department of Wildlife experts concluded the lake's entire fishery - some 100,000 trout, catfish and bass - was wiped out. Biologists determined the die-off was likely the result of a "violent turnover" of the lake's waters associated with a cold snap that sent Reno-area temperatures to near zero. Such events can rapidly diminish oxygen levels in the upper levels of the lake and cause oxygen-poor waters from the bottom to rise to the surface. On Monday, experts with the Department of Wildlife tested the lake's waters and while healthy levels of dissolved oxygen were found in some locations, poor oxygen levels of 4 to 5 parts per million were found in others. Any levels less than 4 parts per million can be dangerous to trout. "It's not the total zero we saw last year but it does look like we're having another turnover," Department of Wildlife spokesman Chris Healy said. After dissolved oxygen levels at Sparks Marina returned to normal levels last March, the department began restocking trout in effort to rebuild the popular fishery. Some 50,000 rainbow trout, about twice the amount normally stocked, have since been put in the marina at a cost of about $1 per fish, Healy said. The fact that two die-offs have occurred over the course of one year is a "big surprise" that warrants further investigation, Healy said. Discussions with Sparks officials about artificial aeration of the lake's waters are possible, Healy said. "We're definitely going to have to talk about it," he said. Aerating such a large lake, Mayberry said, would likely prove "very, very costly." "Clearly it's a concern this damage is being done to a very popular fishery," Mayberry said. "That's something we're going to talk with NDOW officials about in the days to come." Windy conditions on Tuesday could improve oxygen levels at Sparks Marina, Healy and Mayberry said. He stressed that the water quality of Sparks Marina remains good and the water presents no danger.

Event updates:

Situation Update No. 1 on 2015-01-03 at 04:25:26.

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