They say that before you criticize someone, you should "walk a mile in their shoes".
Joe South made a living turning metaphors into songs, including "Games People Play", "I Never Promised You a Rose Garden", and "Walk a Mile in my Shoes"
Restore Hetch Hetchy decided long ago that it was essential to care deeply about San Francisco's water supply needs. Our campaign for restoration will not be successful if we cannot show that San Francisco will still be able to get the water it needs.
Take the water, San Francisco, but don't store it in Yosemite.
Photo: Matt Stoecker
Early on, we adopted this mission statement: "The mission of Restore Hetch Hetchy is to return the Hetch Hetchy Valley in Yosemite National Park to its natural splendor ─ while continuing to meet the water and power needs of all communities that depend on the Tuolumne River." More recently, we have emphasized the water supply element of this commitment as "not a drop of water supply need be lost".
The analytical work that we and others have done goes well beyond these statements. While the vast majority of water deliveries could be made with minor conveyance improvements, some new storage, above or below ground, or a new source will be needed to ensure no loss of supply.
All water agencies worry primarily about surviving a succession of dry years - a "drought". San Francisco is no exception. Indeed, the parameters of it system makes it particularly vulnerable in the driest years. As a result the City has invested in surface storage equivalent to about five years of its system wide water use - see Figure 1.
San Francisco's system includes 3 reservoirs in San Mateo County, 2 in Alameda County and 4 in the Tuolumne watershed. Its share of Don Pedro Reservoir, which is operated by the Turlock and Modesto Irrigation Districts, is usually characterized as a "water bank". The City paid 51% of the cost of Don Pedro's construction in exchange for the bank and relief from flood control obligations upstream. Improved cooperation between the City and the Districts will make restoration easier to realize.
In most years, the Tuolumne River provides more than ample supply to San Francisco. Between 1971 and 2010, San Francisco diverted an average of 224,545 acre-feet of supply. During this period, San Francisco's water rights entitled the city to about 44% of the river's flow, of 864,510 acre-feet of the river's flow. So, on average, the Tuolumne River provides the City with almost four times as much water as it needs.
In the driest years, however, San Francisco gets very little water under its rights. Almost everybody gets less water in dry years, but for San Francisco there is a double whammy, because its water rights are junior to those of the Turlock and Modesto Irrigation Districts. For the six-year drought between 1987 and 1992, San Francisco received only an average of 151,102 acre-feet under its water rights, forcing it to make substantial withdrawals from storage to meet customer needs. This was a challenging period indeed.
As a planning mechanism, San Francisco assumes an even worse case scenario might take place. The City uses a "Design Drought" for its planning, in which the 1987-1992 drought would be followed by the very dry years of 1976 and 1977. Specifically, the City's planning objectives include:
- Our water supply planning is driven by drought conditions. There is plenty of water in normal years, but extended droughts are a big challenge.
- Our Level of Service objective for water supply (adopted in 2008) is to survive a specific 8.5-year drought planning scenario (1987-92 followed by 1976-77) with no more than 20% rationing from a total system demand of 265 MGD.
In such a "Design Drought", San Francisco would receive only 111,111 acre-feet on average over 8 years - requiring even greater reliance on stored water.
San Francisco's "junior" rights entitle it to 44% of the Tuolumne's flow on average, but only 16% during the 1987-1992 drought, and only 14% during the Design Drought. A double whammy indeed.
Some have opined that San Francisco should restrict its drought planning to droughts that have actually occurred in recorded history. Restore Hetch Hetchy is content to "walk a mile in their shoes", and accept the City's water planning objectives. We plan to show that the City can improve its system so it can deliver equally reliable water without Hetch Hetchy Reservoir - under any set of planning objectives.
We are hopeful that the appellate court will soon adopt the recommendations of the California Attorney General and State Water Board, and send our case back to the trial court for a hearing on the merits of restoration wherein the necessary water supply improvements will be fully considered.