Mono Basin: Tufa

Tufa towers are unique calcium carbonate formations. They are formed when calcium-bearing freshwater springs well up through the alkaline lake water, which is rich in carbonates. Groups of tufa towers and sand tufa deposits are scattered around Mono Lake's shores. The towers range in height from a few inches to 10-25 feet. They are unusual light gray or white rock formations of spines, pinnacles or knobs. They rise abruptly from the shore or near-shore lakebed.

The south Tufa, shown in this photo is the largest of the visible Mono Lake tufa groves. The South Tufa deposits are relatively young and may have formed after irrigation began in the upslope Pumice Valley in 1920 as percolating irrigation waters reached the lake. They are shallow rooted and susceptible to undercutting by wave action during rises in lake level.

 
South Tufa (photo courtesy of the Mono Lake Committee)

The photograph was taken in 1995 in the County Park on the northwest shore of the lake. The boardwalk meanders to the lake through the willows and marsh of the Mono Lake Tufa Sate Reserve. I'm kneeling to point at a plaque. The plaque informs visitors that the lake stood at this elevation (6392 feet) back in the year 1963. The current policy is to allow the lake to return to this level

The photo shows one of the tufa towers in the County Park tufa grove, also known as the DeChambeau Creek tufa grove. These tufa structures are older and more rounded or domelike than those in the South Tufa grove.

You can see the waters of Mono Lake in the background. Now visualize the lake waters when the lake reaches the target elevation. Clearly, the base of the tower behind me will be submerged. Jones and Stokes (1993, table 3I-6) estimates that 40% of the towers in this grove will be submerged at their base and around 5% will be totally submerged when the lake returns to the target elevation.

 
Author's Photo taken in Nov 1995 at the plaque marking the
elevation 6392 feet, the target for Mono Lake.

In Storm Over Mono, John Hart explains that the tufa was a key factor leading to the Board's final decision to limit the target elevation at around 6,392 feet. The South Tufa grove is a particularly important site for visitors to the lake. If the lake were allowed to rebuild to the 6410 feet,for example, all of the towers at the South Tufa grove would be toppled or submerged. With the 6390 feet alternative, on the other hand, around half of the towers wold be toppled, and around 20% would be submerged at their base (Jones and Stokes 1993, table 3I-6). Hart explains that that 6390 feet elevation was viewed as a way to preserve a smaller version of the South Tufa grove to allow visitors to view the towers protruding from the water in "their most spectacular setting" (Hart 1996, 173).