Fish Die-off in Nevada Lake

100,000 Fish die in Helms Lake, Sparks, NV

As many as 100,000 bass, catfish and trout have died since mid-December in Helms Lake, a man-made 77-acre stocked fishery located in Sparks Marina Park, a popular recreation complex near Reno, Nevada.

State and wildlife officials are baffled as to what caused the unprecedented die-off, revealing that low oxygen levels in the water had killed about 3,000 fish in one area of the reservoir in December.

State biologists say the drop in oxygen levels may have been caused by a recent cold snap stirring low-oxygen waters.

“We’re seeing oxygen levels that are totally lethal to fish,” said Nevada Department of Wildlife spokesperson Chris Healy.

“Fish gain oxygen from water cycling across their gills and suffocate when oxygen concentrations dip below a certain level. Many types of fish struggle or die when oxygen is below 5 parts per million. Sampling of water across the lake has shown so-called dissolved oxygen as low as 1.1 parts per million,” reported Reuters  citing Healy.

Water Quality

However, Sparks Marina says its lake is continuously recharged with fresh, filtered water from an underground aquifer, and that the recharging process, which is similar to an artesian well, produces a water quality that exceeds the EPA standards for recreational use.

Helms Lake, a 77-acre man-made lake in Sparks Marina Park, Sparks, a city located east of Reno, NV, contains an estimated 1 billion gallons of water with a naturally occurring aquifer that replenishes the lake with 2 to 3 million gallons of fresh water daily. The lake has an average depth of 60 feet, with the deepest point being approximately 120 feet. The average temperature in the deepest parts is in the 40’s all year around, while the shallow areas will heat into the 70’s during the hot summer months, according to the park’s website.