Upstream. downstream on The Tuolumne River (part 3 of 3)

State Water Board Tuolumne River Proposal (part 3 of 3)

San Francisco's water rights are junior to Turlock and Modesto

The Tuolumne River is oversubscribed (see part 1 or part 2)

Turlock and Modesto are the oldest irrigation districts in California. Together they use about four times as much Tuolumne River water as the Bay Area. (My recent editorial opinion the San Francisco Chronicle understated this factor by saying they used only three times as much of the river's flow.)

figure_1.jpgThe Districts (as they are often called) have a cooperative but tenuous relationship with San Francisco. They were initially opposed when San Francisco sought Congressional permission to build Cherry, Eleanor and Hetch Hetchy Reservoirs in the upper watershed, and withdrew their opposition only after language explicitly recognizing the seniority of their rights to the Tuolumne River's flow was included in the Raker Act.

Like many places in California, these historically derived water rights on the Tuolumne can be described by the highly technical term "cattywampus" (also explained in a blog two years ago). In dry years like 2014 (see Figure 1), San Francisco gets almost nothing.


In the 1960's, due to their junior water rights, San Francisco was highly motivated to invest in additional storage. The Districts and San Francisco agreed to build Don Pedro Reservoir on the lower Tuolumne River, replacing the much smaller reservoir with the same name.  In summary:

  • Don Pedro holds up to 2,030,000 acre-feet of water, approximately 6 times the volume of Hetch Hetchy Reservoir;
  • Don Pedro is owned and operated by the Districts;
  • San Francisco paid 50% of the cost of constructing Don Pedro;
  • About one third of Don Pedro (twice the volume of Hetch Hetchy Reservoir) is dedicated to a "water bank" for San Francisco, which allows San Francisco to divert water upstream that would otherwise belong to the Districts; and
  • The Districts would be responsible for meeting downstream flow requirements in place at the time, but San Francisco would be responsible for meeting 50% of any increase in required flow.

The State Water Board's proposal that 40% or more of the Tuolumne River's natural flow be left in the river would require substantial changes, not only for San Francisco but for the Districts as well. The Districts do not want to give up any water- to the lower river or to San Francisco and have launched the Worth Your Fight website to rally fierce opposition within their communities. 




The Modesto Arch is a reminder of how the community feels about water.

From a revenue perspective, the Districts look like electric utilities, but water still drives politics in both communities.

From the State Water Board's perspective, the Tuolumne is an oversubscribed river. In many years, the Tuolumne below Don Pedro retains less than 10% of its natural flow. The State Water Board understands the challenges faced by the communities that rely on the Tuolumne and other heavily depleted rivers, but its job is to determine how water supplies ought to be balanced to maintain a healthy Delta while still recognizing the needs of our cities and farms. Finding and achieving that balance is a challenge.

San Francisco's obsession with developing the Tuolumne River more than a century ago has led to both of the environmental conflicts it faces today - being the only city to occupy a substantial portion of one of our national parks and being one of the communities which has substantially depleted the Tuolumne River. 

In the early 1900s, San Francisco considered, and rejected, alternatives to convey water from other Sierra Rivers, including the Feather, Yuba and American which were, and still are, less developed. The City became obsessed with the Tuolumne River and Hetch Hetchy, in part due to the prospect of hydropower production and public power for the City (public power never materialized, a disappointment to its advocates).

Dam builders a century ago saw little need to consider the health of rivers and wetlands downstream. Their mission was keep water from "wasting to the sea".

In hindsight, however, San Francisco's obsession with developing Hetch Hetchy Reservoir and other dams on the upper the Tuolumne River seems questionable. The City has been forced to make substantial additional investments to insure reliable supplies, and these supplies are today further in jeopardy due to downstream needs of the Bay-Delta and its fisheries. 

And, San Francisco, which prides itself as being "green" and "progressive", remains the only city in the United States to have so destroyed such a spectacular part of one of our national parks. We are committed to restoring the Hetch Hetchy Valley and returning it to Yosemite National Park and the American people.

So San Francisco is being squeezed at both the top and bottom of the Tuolumne River. As we proceed with our mission of restoring Hetch Hetchy to its natural splendor, we will also keep close tabs on what's going on downstream.