100,000 dead fish turned up in Nevada's largest urban fishery this winter, and scientists say low oxygen levels are to blame.
Over the last month, scores of dead fish, including bass, trout and catfish, were found dead in Sparks Marina just outside of Reno, Nevada. The massive fish kill had scientists and locals scratching their heads trying to figure out how all the fish died.
"All the fish don't just die," resident Rick Dinoso told the Associated Press.
After a series of tests on sections of the marina, state environmental officials now believe the massive fish kill was caused by a sharp drop in the water's dissolved oxygen levels. The leading theory is that a cold patch last December, when temperatures in the area dropped to 0 degrees, caused the water's oxygen levels to significantly drop. Another postulation is that last year's hot and dry summer produced large amounts of oxygen-hungry algae growths.
RELATED: Read about a similar scenario that occurred last December in a Minnesota lake.
State environmental officials say that despite the dead fish, the low oxygen levels won't affect the public's safety.
"It's not good for the fish obviously, but the water quality itself is great and there's no health or safety issue," city spokesman Adam Mayberry told FOX News. "Other than fishing, there's no indication you can't do anything else out there that you have always been doing."
While environmental officials have said tests do not indicate any contaminants, the marina has had toxins leak into it in the past. Sparks Marina used to be a large rock quarry. A few of the locals remember the days when the marina was used as a dumping ground for garbage.
"In the old days you would just back up the truck and dump it all out," a Reno resident Kristine Rowland told the AP.
In the 1960's, a nearby petroleum tank farm leaked contaminants into the quarry pit. Those contaminants were discovered in the Marina's groundwater in 1988 and subsequently pumped out. Wildlife officials said current tests indicate that no pollutants from the tank farm were found in the lake.
The massive fish kill is a huge blow to Nevada's largest urban fishery. Wildlife officials usually restock the marina each March, but they said they plan on waiting until the oxygen levels reach more normal levels.