Water Supply Solution: How California can thrive during the next mega-drought

The main constraints to having sustainable water systems (both human and natural) in California are not technological or economic, but political and social. There is a very simple (simple to lay out but hard to politically follow through) process we need to go through to achieve sustainability. And if the word "sustainability" rubs you or your audience the wrong way, then just replace it with "reliability" which means the same thing over the long term.

Right now we try to "use" every bit of water we can. In a variable climate like California's, and with a water rights system like ours, that is a recipe for disaster--we expand our "needs" in wet years and they must inevitably contract in dry years. This is not sustainable, or reliable, or any way to try to build anything stable. The Westlands (a low-priority water right) should never have been irrigated because
those lands rely on surplus water, which is unreliable. Human and economic systems built on that unreliability will cause people pain. Political solutions will tend to focus on how to support what exists, even though that will cause ecological catastrophe in dry times. What exists may not belong there--but good luck finding a public figure with the political will to be honest about that.

We must begin to rely only on what is available in dry times, and let ecosystems have everything else. This will result in both healthy economies and ecosystems. In other words, we must set limits and stick to them.

A process that all water systems must go through is the only politically fair and feasible way to weed out the unsustainable ones, like the Westlands Water District (sorry to pick on Westlands, but they have set themselves up as the bad guy in California water, both by intention and historical accident). 

Here is my proposed process. This focuses on volume and not the timing of flows, which would require a similar process. This isn't that different from the successful process achieved in the Mono Basin, although it starts in a slightly different place.

1. For each watershed, river, groundwater basin, or water system of interest, determine the lowest annual long term volume of water likely to be supplied. Based on hydrologic records and tree ring records, what I want to know is what is the driest day, month, year, decade, and century I should expect? And lets employ the precautionary principle--be conservative. We don't want to rely on something that isn't there. Any uncertainty sends the extra water to ecosystems in this methodology.

2. During those dry times, how much water do the water-dependent ecosystems need?

3. How much water remains? That remainder is what is available to divert to human uses in ALL years, not just dry years.

4. Reduce water rights and human uses to those dry levels.

5. In systems with reservoirs, water rights and uses can be expanded to use the proportion of storage available during the dry time that can be filled up again during the wet time, and wet year uses can be expanded over dry year needs to fill the reservoirs.

For example, a watershed yields 100,000 ac-ft on average, however during the dust bowl drought it yielded 300,000 ac-ft over a decade. This is 30,000 ac-ft per year, and the ecosystem needs 15,000 ac-ft of that. This leaves 15,000 ac-ft per year available for water rights and human uses in all years (because when that dry time returns you don't want to need more). If there is a reservoir that holds 50,000 ac-ft of usable storage (assuming no other constraints e.g. flood control), and our dry-times analysis shows that the water in it only needs to last a decade before it can fill up again, that makes another 5,000 ac-ft (one-tenth of the storage) available each year, for a total of 20,000 ac-ft per year of human needs. This means that in an average year, people use 20,000 ac-ft and ecosystems get 80,000 ac-ft. In a dry year people still get 20,000 ac-ft (for the first decade until the reservoir goes empty--after a decade of worst-case-scenario drought 25% water conservation would be required) and ecosystems get 15,000 ac-ft. In a 200% of average wet year, assuming the reservoir was full, humans would get 20,000 ac-ft and ecosystems would get 180,000 ac-ft.

This may seem a bit simplistic. Each watershed would have its own twists and turns on this idea... and most would end up with quite complex analyses. But you have to start somewhere. Is it unrealistic? Maybe there would be some successes and maybe there would be some failures, but as Aldo Leopold said,

"We shall never achieve harmony with land, any more than we shall achieve absolute justice or liberty for people. In these higher aspirations the important thing is not to achieve, but to strive."

Success would result in stable human and ecological communities. Endangered species would no longer compete for water. And neither would humans. Once we reduce our needs to what nature provides, we will live in a culture of abundance, as opposed to our current culture of scarcity.

This reminds me of the drivers on the road that are always tailgating, and their speed is always limited by the car in front of them. Drivers that slow down a little and increase their following distance will get to set their own speed that is more consistent and less susceptible to sudden outside influences. Self control and self-imposed limits = more stability and safety. You just have to slow down a little to reap the benefits.

The hard part is getting there, but we can do it. If we start working on this now, perhaps before the next mega-drought we will have transformed our society and economy into something that can not only weather a century-long drought, but thrive during it. And we won't compromise our precious ecosystems either.