Water storage for a not-so-rainy day

We all know water storage is important in a state like California.

Rain is almost nonexistent for half the year and multiyear droughts occur way too often. Water storage has long been and will continue to be necessary for California's communities, businesses and agriculture to survive and to thrive.


How to develop sustainable water supplies throughout the state is very much on everybody's minds in this fourth year of drought. It is a question that Restore Hetch Hetchy has always been committed to answering, at least for San Francisco and its Bay Area customers. We have always understood that restoration will take place only if we can assure than no water supply will be lost.

There are other tools, of course, that are important for developing sustainable supplies and effective water management programs. Crop choices, efficiency, recycling, marketing, land-use planning and other factors all play key roles in the big picture. But storage is still high on the list for many water agencies and policymakers.

Both houses of Congress have produced bills in furtherance of five new and/or expanded reservoirs that were proposed 15 years ago in a joint federal and state process known as CALFED (I wrote about these on June 26). The bills differ principally in that the house version (Rep. Valadao, Fresno) would also direct less water from federally controlled facilities to fisheries and more to agriculture. The Senate version (Senators Feinstein and Boxer) would leave current policies unchanged.

Only one of these proposed projects, Temperance Flat on the San Joaquin River, would be a major new storage facility on a free flowing river. Shasta Dam would be expanded, inundating additional reaches of the Sacramento and McCloud Rivers and other streams that feed the reservoir. The other three projects would be new or expanded offstream reservoirs.

As a state, California is taking a different approach - one that is intended to consider both surface and groundwater storage projects, with the better projects being awarded state funds for up to 50% of the cost. Proposition One, the water bond passed in November 2014 provides up to 2.7 billion dollars for the "public benefits" associated with new storage. While Proposition One identifies these specific reservoirs as potential recipients, it says the money can be applied to groundwater projects as well. The California water commission is tasked with evaluating proposals for spending these billions on water storage, which will also require interpretation of the phrase "public benefits" as defined by the bond language.

The California Water Commission's deliberations should prove interesting. In recent decades, the direction of water storage development has inexorably been in the direction of groundwater recharge rather than additional surface reservoirs. 

Since 1990, more than 5,500,000 acre-feet of water storage have been developed in California in the locations shown in Figure 1.  Two of these projects, Los Vaqueros and Diamond Valley Reservoirs, are "off-stream" surface reservoirs. Most other large projects are groundwater aquifers that have been developed either to serve local communities or to use as "banks" that exchange ground and surface supplies, using California's vast network of canals, with distant communities in dry years.

Over the last 20 years, water agencies have invested far more in groundwater storage projects than they have in surface storage. When discussing groundwater development, it is first and foremost essential to distinguish between drilling new wells simply to "mine" limited and unsustainable supplies and installing injectors, establishing recharge areas or other infrastructure so that aquifers can be deliberately replenished in wet years. Figure 1 below illustrates the size of some of these projects and compares them to the size of Hetch Hetchy Reservoir.


Restoring Hetch Hetchy Valley in Yosemite National Park depends entirely on a fair and cost effective plan to replace the water supply provided by Hetch Hetchy Reservoir. We are convinced it can be done and we look forward to presenting alternatives in the California courts. 

Please contribute to the campaign to return Hetch Hetchy Valley to Yosemite National Park and all people.