Lake Tahoe was a little murkier last year compared to the year before.
Researchers say a lack of snow is likely to blame for the reduction of 4.8 feet in clarity.
Geoff Schladow is with the UC Davis Tahoe Environmental Research Center. According to him, snow runoff is so cold it carries particulates to the bottom.
"Rain - it's somewhat warmer and warm water is lighter and all those pollutants that cloud the lake are coming in closer to the surface."
Only 5.3 percent of the precipitation last year was snow, the lowest percentage in more than a century.
Schladow says the average depth for clarity level was about 73 feet last year. That still is a little better than the 15-year average of 71 feet.
Researchers measure water clarity 30 times each year. They use a long pole with a disk at the end and submerge it until it disappears from view.
The lake's average clarity was at its lowest two decades ago when it measured just 64 feet.