It was a little harder to see down into Lake Tahoe last year than it was the year before, and researchers say the drought is a contributor to the decline in Tahoe's clarity.

The measurements taken through 2015 put Tahoe's average visibility depth at a little more than 73 feet, a decline of nearly five feet from 2014, down in both the summer and the winter months.

The U.C. Davis researchers who have been taking the measurements for about the last half-century say with the drought, the lower snow-to-rain ratio led to warmer water flowing into the lake. That took fine particles with it, and it kept them closer to the surface, which affected the clarity.

Tom Lotshaw with the Tahoe Regional Planning Agency says it is not a long-term trend.

"The clarity decline peaked around 15 years ago," Lotshaw said. "Since that time, there's been a slow and steady stabilization and improvement trend over that time."

Lotshaw also says that since pollution and fine sediment from storm water runoff also does a number on the lake, there has been steady work to capture that storm water, including about a half-billion dollars in highway improvements from Caltrans alone.