UC Davis has revealed in its annual Tahoe: State of the Lake Report that the lake has been warming at an alarming rate along with significant changes in its clarity, physics, chemistry and biology over time.
Researchers at the UC Davis Tahoe Environmental Research Center note in the report that lake Tahoe has warmed at an alarming rate of over 0.3 F per year and that this warming is 15 times faster than the long-term warming rate and average surface temperature of the lake was the warmest on record, 53.3 F.
Scientists have long known about the increase in air temperatures over the lake and the latest study has found evidence of surface water temperature increase. Along with these findings, researchers note that they have observed changes in the lake’s internal physics and this they say is going to have ecological impacts.
Some of the other findings highlighted in the report are change in precipitation at the lake due to climate change, lack of adequate mixing and for the year 2015 the mixing depth of the lake was 262 feet which is the lowest recorded. Deep mixing that a lake undergoes in the winter is crucial for adding oxygen to the depths and redistributing nitrogen that tends to accumulate at the bottom.
Scientists also point out that the attached algae around the lake’s margins were at record-low levels and this was largely due to the low lake level, which fell by 9 inches in 2015. Lake Tahoe was below the natural rim for all but one day in 2015, so no water could flow into the Truckee River.
Clarity of the lake was another thing the researchers looked at and measurements indicate an average annual clarity of 73.1 feet in 2015, a 4.8-foot decrease from the previous year, a measurement announced in April 2016. The decline was due in part to warmer inflowing water.