Mono Lake, North America's Oldest Lake

One of the disadvantages to traveling the eastern Sierras is that it's a long way from most people's homes. Most of northern California has to come all the way over the mountain passes to get there, and southern Californians have to drive several hundred miles along Highway 395, through some of California's most inhospitable terrain before arriving at their destination. Of course, it could be argued that one of the best reasons for coming to the eastern Sierras is because it's hard to get there, and therefore doesn't receive the tourist pressure of other parts of the state.

However you look at it, a trip to the eastern Sierras when you have time is sure to be a rewarding experience. If you hunt or fish, some of the state's best locations are on the eastern slopes. If you hike, the entire Sierra Nevada is accessible. Photography enthusiasts can find some of the most striking scenery anywhere around, and people just interested in the area can find a history that's rich in fact and lore and a geology that's anything but boring.

Mono Lake is a perfect example of the richness of the story of the eastern Sierras. Located at Lee Vining, or just outside the Yosemite National Park, this expansive lake is possibly one of the most interesting places in the Sierras. Formed approximately 760,000 years ago through volcanic activity in the Long Valley Eruption a few miles south, it's thought that this lake is the oldest lake to continuously hold water on the North American continent.

While several small rivers feed the Mono basin, the only natural outflow of water is through evaporation, which accounts for about 45 inches of water per year in the lake. Because no water escapes through streams or rivers, all of the salts and minerals that wash down out of the mountains in the normal course of erosion have been trapped in Mono Lake, giving it more salinity than any of the world's oceans. It's been estimated that Mono Lake contains 280 million tons of dissolved salts, but the significance of that number isn't as revealing as the total ratio of salts per liter of water compared to most oceans. While ocean water contains about 31.5 grams per liter, Mono Lake contained about 50 g/l (grams per liter) in 1941 before the City of Los Angeles started diverting water from the water shed. When the lake reached its lowest level in 1982, the ratio was 99 g/l; over twice its normal level, and about three times the level of the oceans. When water diversions were reduced, the lake began to rise once again. In 2002, the amount of salinity was 78 g/l. When it reaches its target level, it's estimated that the total salinity will be at around 69 g/l. This process will take about twenty years to complete. In addition to lots of salt in the water, the ph is considered extremely high – about 10 on a scale of 1 to 10 – compared to seawater at 7.4 to 8.5 ph.

Because of the hyper salinity and extremely high alkalinity, fish do not live in Mono Lake. It's not clear if they ever did, but they certainly have not in recent history. Because there are no fish is certainly not to imply that there is no life here. In fact, there is an abundant life structure that supports a rich eco-system.

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