It would be arguably the most ambitious public works project in San Diego history.

The envisioned pipeline would carry Colorado River water more than 130 miles from the Imperial Valley — through the Anza-Borrego Desert State Park, tunneling under the Cuyamaca Mountains, and passing through the Cleveland National Forest — to eventually connect with a water-treatment plant in San Marcos. An alternative route would run through the desert to the south, boring under Mount Laguna before emptying into the San Vicente Reservoir in Lakeside.