Last weekend Stephanie and I ventured all the way through Yosemite to get to Mono Lake on the other side. We didn’t really have a reason to go, except that it was there. After stopping for lunch in the town of Lee Vining, we went to explore the Tufa rock formations in the south of the lake.

Tufa, a type of calcium carbonate, is formed when mineral-rich springs under the lake react with the alkaline lake water. The towers that are currently visible all used to be hidden under the surface of the water—where they form—until 1941, when fresh water sources that fed the lake were diverted to the city Los Angeles. This caused the lake level to drop 45 feet, from 6,417 feet above sea level to 6,372, thus exposing the tufas.

Unfortunately this also had a disastrous effect on the unique ecology of the lake. It increased the salinity of the already hypersaline water, threatening the lake’s 4-6 trillion brine shrimp, a vital source of food for migrating birds, it created land bridges to islands in the lake where birds used to nest, exposing them to predation, and it exacerbated alkali dust storms due to the exposed lake bed.

In 1994, after a 16 year legal battle, an agreement was reached to restore the lake to a goal of 6,392 feet above sea level. It’s currently somewhere around 6,382. It’s very likely that when it reaches 6,392 feet, the tufa towers we saw will once again be under water.