Images from the Millerton Lakes Cave System

One of the world's most unique cave systems may be threatened by some of the plans now being considered by the State Legislature to expand water storage capacity on the San Joaquin River in central California.

The cave system at Millerton Lakes is the world's most notable example of a corrasional cave (i.e., scoured out by abrasive material, rather than dissolved) formed in granite. Almost a mile long, it has been sculpted over thousands of years by an active creek that runs year-round. Caves in granite are far less common than those formed in limestone or marble, and typically are just passages among boulder piles.

Millerton, by contrast, has been sculpted along an unusual convergence of a fault and a joint, and has beautiful stream-cut canyons in solid bedrock. It is noted for its well-developed speleogens such as sculpted blades, flutes, pendants, and potholes in bedrock. Besides its scientific value, the cave offers unique recreational opportunities.

Some of the current proposals for expanding storage capacity along the San Joaquin River, such as building the Temperance Flat Dam, will totally flood the cave system. Several alternative proposals would allow increased storage without inundating the cave. Please, help save this unique underground gem.