Below the dam, Los Angeles has kept lower Rush Creek – once the finest brown trout stream in the eastern Sierra – bone dry. That is, until three wet winters a few years ago swept trout over the dam. These fish actually re-established their own wild spawning population once again, though perhaps only temporarily. The creek would be dry through the summer, were it not for a temporary injunction brought on best mountain bikes under 300 by fishermen’s groups and the Mono Lake Committee, which has been fighting to protect Mono Lake. The injunction requires Los Angeles to maintain a 19-cubic-feet-per-second minimum flow. Anglers have been treating the reborn creek as a wild catch-and-release trout stream.
Returning to U.S. 395, head south, crossing Rush Creek, and turn left onto State Highway 120, east toward the Mono Craters, which tower 2600 feet above the surrounding plains. These volcanic craters are practically newborns in geologic terms. This is especially true of Panum Crater. You can take a short trip to the crater’s rim and take in the surroundings. Panum Crater was formed only 640 years ago when explosive eruptions piled up pumice to create the rim, set up by the oozing of a glassy, obsidian plug. To the west, Sierran canyons show the broad U-shape of glacier-carved valley. Mono Lake itself rests in a bathtub-shaped basin with the eastern Sierra as the wall, with faucets on one end and with volcanic highlands forming the rims, but this tub loses water only to evaporation. Today, it is drying up because of Los Angeles’ diversion of four of the five Sierran streams that flow toward Mono.
Return to Highway 120 and turn left. After about three miles, turn left onto a dirt road, then follow the left fork. This takes you to an interpretive trail at the South Tufa Grove. Tufa is one of the most peculiar products of the lake, owing its existence to Mono’s unusual chemistry. Mono’s water is three times as salty as the sea and about 80 times as alkaline, which makes it feel soapy. One type of these salts is carbonates – chemically related to baking soda – which react with the calcium in spring water as it wells up from the lake bottom. The result is tufa. The fragile, other-worldly sand tufa at the nearby Navy Beach was formed in the same way as the tufa towers, except that the calcium carbonate formed in sand. The hardened calcium carbonate holds the grains of sand together in fragile formations.