What Does Climate Change Really Mean to California’s Water Resources?

August 6, 2019 Robert Shibatani Guest blogger

By Robert Shibatani

Whether you are a water utility manager, elected official, or homeowner, future water availability is a concern. There are several factors fostering that concern and one of them is climate change. In fact, these days, climate change is a rapidly growing global hot topic (no pun intended). But as the empirical evidence mounts and a once doubtful citizenry become more informed, it is instructive to review what a changing climate fundamentally means to California’s water resources; arguably our most important.

There have been many reports, commissioned studies, Statewide Plans, visionary and mission statements over the years, each providing an enlightening overview of the climate change state-of-knowledge at the time and what the most recent evidence was indicating. Outstanding efforts have been made by several State authorities to bring this information to the public. Most of our State leaders now acknowledge climate change as a clear and present danger. Their commitment, often in the face of less than fully supportive administrations in D.C, is highly commendable. However, there is much left to do, but California is one of the leading U.S. States in the dissemination of climate change information.

Today, we can say that there is agreement on some basic expectations for future water resources in the State as a result of continuing climatic change. But what does that really mean? How will it directly affect California’s waterbodies and waterways? How will it affect all of the water utilities, irrigation districts, water conservation and flood control districts across the State? And how will it affect each of us, the consumer, beneficial user, and resident of our daily necessities and activities?

The primary question is somewhat misleading since one cannot realistically decouple water resources from all of the other natural resources, processes and managed activities that make up our livelihoods. All of our social, cultural, financial, and recreational pursuits. To give the question fair tribute, a thorough multi-disciplinary review of all the secondary and tertiary direct and indirect effects would be necessary. But we’ll leave that to another time. For the purposes of this narrative, let us confine ourselves to strict water resource-related activities.

Water resources across the State can be broadly grouped into two primary categories. First, the inherent or ambient resource itself; which would include all of the waterbodies, waterways, and conventional storage. Second, the managed portion of the annual cycled resource; this includes what we do with all of the snow, meltwater, and rain we receive each year, how and for what purposes. These two categories represent the majority of the State’s static water resource reserves at any given time.

Conclusions from many early studies on California’s water resources have not materially changed. We have to remember that the early projections, despite seeming precision, were based on spatial and physical limitations (relative to today) and at rudimentary spatial scales that did not offer the majority of field water managers the resolution needed to establish definitive conclusions about future climatic projections; certainly not sufficient enough to develop specific management prescriptions.

For California, there are several broadly accepted projections. For example, everyone accepts ongoing and accelerating snowpack depletion. That means a reduced spring freshet until, at some point, the complete elimination of “melt-enhanced” spring flows as annual hydrographs for California reservoir inflows become direct rainfall-runoff generated. On the one hand this becomes easier to project and simulate since the inflow is a direct function of tributary inflow, on the other hand, it requires more judicious winter-spring operations as carryover must be more carefully managed; the spring refill can’t be continually relied upon.

Changing hydroclimatic character across broad swaths of the State will lead to net wetter and drier areas. The inflection point between wetter and drier as systems from the interior Pacific move inland is still a crude projection; likely lying somewhere between Santa Barbara and the Bay Area. Along with net changes in annual precipitation, the intensity and frequency of measurable events will also pose considerable threats to the State’s infrastructure, commerce, and resident livelihoods.

Major rivers and their higher order tributaries will see altered flow regimes. Some will be drastic, others more muted. A real concern to all water users of these waterways and waterbodies is the regulatory and institutional approvals that have been granted by regulatory agencies; approvals that were based on an analysis of the hydrology of the past and now bear increasingly little similarity to what we can expect in the future. This growing incompatibility will extend from water rights, to water quality permits, to water transfers, to power purchase agreements, to flood control operations, etc. Somewhat surprisingly, particularly for California, is the fact that virtually no effort has been undertaken to assess the potential extent, depth, and implications of these incompatibilities. Regulatorily, we are blindly stumbling ahead with climate change in terms of water resources adaptation.

Over the next 30+ years, we will see notable changes in riverine hydrology across the State. Some extreme year sequencing will generate elevated concerns, but nothing that can’t be endured in the short-term.

The real concern is that the water industry is focusing on the wrong issues, having been influenced by the GHG curtailment lobby. A zero-carbon footprint (assuming such a lofty goal is even possible), while laudable, is not going to materially affect a utility or State from major water resource problems. Source control of GHGs must be a federal commitment, not something placed on State- and regionally-based industries. China, India and other SE Asian industry giants must be wooed by D.C., not Sacramento. A utility’s responsibility is to its ratepayers and customers today, tomorrow and next month. Adaptive measures must be developed now, focusing on local/regional delivery and service obligations to ensure continued service.

The State needs a real policy wake-up on climate change … the physical environment is changing and our entire regulatory framework is unprepared …

About the Author:  Robert Shibatani, a physical hydrologist with over 35-years combined academic, legal, consulting and water advisory expertise, is an international expert witness on reservoir-operations, climate change hydrology, commercial flood damage litigation, and water supply development.  He is Managing Partner for The SHIBATANI GROUP International, a division of The SHIBATANI GROUP Inc. and resides in Sacramento, California. robert@theshibatanigroup.com