California is a land of extremes – where preparing for extremes must be constant and eternal.
The past six years have demonstrated California’s precipitation extremes. From 2012 to 2015, California endured one of its driest periods on record. And 2016 was an additional near-average year, classified into drought because water storage levels were so low.
It seems likely that 2017 will be the wettest year on record in northern California and one of the wettest years ever in most of California. Most of California so far has over 160 percent of average precipitation, with over 150 percent of average snowpack. Reservoirs are now about 2 million acre-feet above their long-term average for this date (having been about 8 million acre-feet below average two years ago).
After wondering for years if the drought would end, the drought is definitively over, even as some impacts to forests, fish populations and groundwater levels will persist for decades. Last Friday, Governor Brown lifted his drought emergency declaration for the state, with a few exceptions. But to keep drought lessons alive, this lifting also stressed a need to reduce wasteful water use and was accompanied by a state plan to make “conservation a way of life.”
What should we have learned (or re-learned) from this decade’s dance with extremes?
- California is a land of water extremes. California is a dry place, which is sometimes much drier than usual for long periods of time – we call these droughts. California also can become very wet – which can cause floods if inadequately managed and prepared for.
- California must manage for both extremes. Wet years allow the gathering of water into aquifers and reservoirs, but we can never economically capture all water in wet years. Even in dry years, we need to prepare for floods, in preparing infrastructure and emergency management. In all years we need to improve capabilities and coordination among water agencies (local, state and federal).
- Conditions can change quickly. The drought took two years to develop and two years to end (although some effects will last for decades). Floods move faster and more violently, seen when Oroville’s spillways tore themselves apart in mere hours.
- Groundwater is key to sustainability and prosperity for California’s human water uses. Increased groundwater pumping replaced about 70 percent of the drought’s agricultural water shortage. Groundwater provides by far the most water storage in California, and is the predominant storage for longer droughts. The 2014 Sustainable Groundwater Management Act shows that this lesson was learned, but implementation remains a challenge.
- The southern Central Valley will see large reductions in net water use. This uncomfortable truth is now widely accepted following the drought. About 15 percent of the southern Central Valley’s agricultural land depends on groundwater overdraft. Problems in the Delta and increased outflows of the San Joaquin River threaten perhaps another 15 percent of supplies. Soil salinization, urbanization of agricultural land, technology and climate change will also mostly push to reduce irrigated acreage.
- Preparation is key to managing extremes – for both droughts and floods. Most cities and farmers did well in the recent drought and floods. A roughly 30 percent loss of water supply reduced statewide agricultural revenue by about 2-3 percent, and urban losses were financially inconvenient but economically negligible. Local impacts were sometimes much worse, especially for some rural communities. The biggest losses were in the areas least prepared. Ecosystems were unprepared for this drought, with often devastating effects. This wet year saw widespread minor flooding, but little major flooding, and identified some areas as needing more attention and funding.
- Future droughts and floods will be a bit different. This drought was worsened by higher temperatures, hit an agricultural economy with many more permanent (and more profitable) crops and hit a system with more effective water supply agency cooperation, and a different compos