At a glance: The Turlock and Modesto Irrigation Districts are advancing an audacious water grab on the Tuolumne River—one that would raise dams, build new reservoirs, and divert nearly every drop of “unclaimed” water, with profound consequences for the river and those who depend on it.
The Tuolumne River is the largest tributary of the San Joaquin River Basin and has been extensively developed as a water supply for the Turlock and Modesto Irrigation Districts (TID & MID, or “Districts”) and the City of San Francisco and much of the SF Bay Peninsula. The Tuolumne and Merced Rivers also provide limited support for the San Joaquin River and its water users (these rivers are essentially the San Joaquin River’s present-day headwaters) and, of course, export customers served by the Central Valley Project (CVP) and State Water Project (SWP) pumps. The Tuolumne River also supports regional groundwater as it sinks into the ground dewatered by modern pumping.
The big historic battles over the Tuolumne River include John Muir’s failed attempt to safeguard Hetch-Hetchy Valley in Yosemite National Park and the scattered objections to the 1921 Don Pedro and 1966 (New) Don Pedro Dams. The Districts and San Francisco’s attempt to license the Clavey-Wards Ferry hydro and water storage project upstream of Don Pedro Reservoir led to the creation of the Tuolumne River national wild and scenic river from the headwaters to the Don Pedro Reservoir gross pool (or near gross pool) in 1984…