Brian Shamblen via Flickr
Emerald Bay in Lake Tahoe as it stands in August 1997. Lake Tahoe has become more polluted by vehicle activity over the years.

Lake Tahoe is considered by many to be a flourishing national park; however, the locals and tourists are damaging the ecosystem drastically with their vehicles. Specifically, water clarity at Lake Tahoe is slowly degrading over time due to the pollutants from cars, which in turn affects climate change and stormwater runoff. According to the Tahoe Environmental Research Center, water clarity in 1968 was at 102.4 feet, while in 2016 the water clarity was only at 69.2 feet.

The research method that has been used to test water clarity for the past 48 years is a white Secchi disk. Named for Italian astronomer Angelo Secchi, the disk is used to measure the turbidity or cloudiness of the water by being lowered in by boat until it is no longer visible. The lowest year was 1997 at 64.1 feet, which is 38.3 feet lost in only 29 years.

TERC’s research seems to show more and more effects of climate change, especially as the water warms and snowfall numbers fall.  The highest surface water temperature was recorded only two years ago at 76 degrees in July, 2015. The lowest maximum water temperature was recorded on March 1, 2015, at 43 degrees. This year Lake Tahoe’s deep water mixing was at an all-time low, meaning less nutrients and oxygen were spread across the lake. This is important because there are also high nitrate levels in Lake Tahoe’s water, causing aquatic life to die.

One of the nonprofit organizations looking to preserve clarity at the lake is Keep Tahoe Blue, which is set on protecting the lake and providing community events for the public. The organization also has research departments, like the Pipe Keepers, who research the runoff of stormwater from pipes that lead into the lake. This research department analyzed over 1,800 stormwater samples over the past year. They also measured the turbidity of the water and fine sediment pollution, according to Keep Tahoe Blue’s recent 2016 annual report.

This type of pollution is also another reason for the decline in water clarity. Fine sediment pollution stormwater mixes with soil, oil, pesticides and other pollutants that are released into the water and can harm aquatic life.

“Pollution is becoming more and more of a problem because of urbanization in Lake Tahoe. Runoff from cars and developments have been seeping into the water and affecting the chemical balance,” said Jenna Zuro, a junior wildlife ecology and conservation major.

Former President Barack Obama visited the 20th annual Lake Tahoe Summit in 2016, which led to the Lake Tahoe Restoration Act that grants $415 million for public Lake Tahoe projects.

“Our warming climate amplifies existing threats: an increased risk of catastrophic wildlife and more precipitation falling as rain than snow, leading to more stormwater pollution pummeling lake clarity,” Obama said during the summit. “This is a cycle that can only be broken by community efforts to lessen the amount of pollution.”

24 million visitors visit in about 9.5 million cars annually, according to the Keep Tahoe Blue Foundation.

“Transportation is the most important issue in Lake Tahoe. Cars are creating fine sediment that goes into the lake and damages the clarity. Therefore, we have started ‘Lime Bike’ to reduce car trips and in the summer approximately 1,200 trips were taken,” said Marissa Fox, Senior Policy Analyst of the Keep Tahoe Blue Foundation.

“Lime Bike” encourages tourists and locals to reduce the amount of traffic and pollution in the Lake Tahoe area. Other options also include carpooling and public transit, which can stop the high amounts of fine sediment pollution into the Lake.

In 2010, Keep Tahoe Blue published a press release on the toxic ozone levels that have been reported in the Lake Tahoe area.  Boats and exhaust are the main reasons for the influx of ozone pollutants, specifically nitrogen. Instead of clean mountain air, locals and tourists are breathing in toxic pollutants.

Katie Shaw can be reached at and on Twitter @NevadaSagebrush.