This post is a thought experiment. Clearly, I’m missing some of the nuance around this issue. However, thinking about how to solve this was fun, and I think some of the below ideas could be useful.

Lately, there has been a loooot of fighting, politicizing and hand-wringing about the drought in California (see CA website). You know it’s been going on for a while when the state government has time to put a webpage up about it!

from MIT’s Technology Review

States measure water in acre-feet, where one acre-foot is the amount of water required to cover an area of one acre to a depth of one foot. One acre-foot is the equivalent of 326,000 gallons of water, or the average use of an American household per year.

Right now, California faces a shortage of roughly 6 million acre-feet. This shortage is due to a lack of rainfall and snowstorms that replenish California streams. To make up for this shortfall, California is tapping groundwater sources (called “aquifers”), drilling deep into the ground to reach non-renewable sources of water.

Scott from Slate Star Codex (one of my favorite blogs on the internet) wrote an excellent piece on the California water drought that’s well worth reading. In it, he pulled together the below infographic that shows where California’s 80million acre-feet of water goes each year:

As you can see, roughly 3.5% of all water usage comes from the 40 million citizens of California. This 2.8 million acre-feet includes every gallon of water used for laundry, toilets, showers and faucets by every person, every year.

Thus, if every person was to completely stop using water for an entire year, the state would still be short 3.2 million acre-feet.

Hmm. Unlikely the voters would pass this.

What about if people stopped watering their lawns? That’d save 3.8 million acre-feet of water per year, leaving “just” a 2.2 million acre-feet shortage.

This faces a similar problem: people won’t stop watering their lawns. And, to be fair, one person watering their lawn once a week doesn’t make much of a difference… but that individual decision, compounded 20 million times over, has a large impact on the California water shortage.

A California entirely run and inhabited by robots would only just have enough water in these drought conditions to continue agricultural and industrial production. That’s not a good sign for the 40 million Californians. So, what options do we have?

Potential Solutions

Before I talk about ideas for potential solutions, I’ll start by saying I will notrecommend anything that has to do with large-scale behavioral change or sweeping policy changes (like taxing or regulating water usage by big agriculture companies). In my opinion, both are unlikely to occur, so I’ll focus on technology solutions.

Idea #1: Raise the Price of Water

In several articles I’ve read online, commenters have said that simply creating a market around water prices would solve this issue. Raise the price, fewer people will use it, and bam: water crisis solved.

However, this article from Bloomberg tells a different story. Farmers in California — that group that uses 40%+ of California’s annual water — arealready paying 10x more for water than they were just a year or two ago. Yet, they keep using water.

Why?

From what I can tell, as a farmer you can’t just stop farming. “Not farming” is not an option. Farmers have already invested in the land, equipment, labor, and machines that make large-scale agriculture work — not farming means they make zero money.

So, what they do instead, in a world of 10x water prices, is plant less and charge more. The article mentions some farmers that can’t get water (or can’t afford it) are leaving large tracts of land unplanted to save money. At the same time, the cost of fruits, vegetables and nuts (of which California makes up half the US supply) is set to rise upwards of 6%.

One area where price increases could have an impact is on well water. Right now, well water — the water source that California is currently drilling dry — is priced as if it will never, ever run out, about 1/10th of a cent per gallon. See below graph for a cost comparison of different water sources (in non-drought conditions):

note: in current drought conditions, irrigation water (the main water source for agriculture) is priced 5–10x more than the $70 per acre-foot this chart suggests.

Under current regulations, groundwater (or well water) comes with land rights. If you own land that’s on top of a groundwater source, you can drill and tap it as much as you like: no restrictions. This has created a dynamic where those who own land with access to groundwater can take as much as they like and sell it to farmers who desperately need it.

So, we see prices going up but little impact on water usage by agriculture (who, if you remember, uses 34 million acre-feet per year). What are some other options?

Idea #2: Individual Water Restrictions

On individual, level, it’s hard to prevent people from using as much water as they want. And, as we’ve seen, if you cut each individual’s water consumption by 25% (installing more efficient toilets, cutting down on showers and water at restaurants, etc.), these rather inconvenient efforts still save only 0.7 million acre-feet. Put another way, by forcing multiple inconveniences on every individual in California, we can get about 11% of the way to closing the water shortage gap. Not very promising.

However, one area I think that’s ripe for potential improvements is in lawn care. You see, lawns are responsible for 3.8 million acres of water-feet usage each year — more than all human water consumption combined. This 3.8 million acre-feet represents 63% of the shortage California faces — fix this, and we’re a lot closer (and with a lot less personal inconvenience) to solving the problem.

Now, I’m not suggesting that we let every yard die and go brown. I lived in Las Vegas for a time, and that’s not a pretty sight. Plus, people want their lawns to look nice — it’s a human desire, on par with wanting to brush your teeth and shower to appear presentable. So, for the purposes of this thought experiment, I’ll assume it’s difficult to get people to stop watering their lawns.

No. Rather, than suggest that, I think there’s a way people can still get the green lawn look, but with much less water. Simply use a different kind of grass!

Most lawns in California use fescue grass, which requires “deep watering” 2–3 times per week.

After a bit of searching, I came across Enviroturf, a kind of grass that only requires deep watering once every 2 weeks.

Now, you’d want to roll this out by replacing many of the current incentives California has for water-saving toilets and showers (like the $125 incentive bonus for installing a water-saving toilet) and using the same money to pay people to re-seed their lawns with a more water-efficient grass seed.

If every household in California replaced their normal grass with Enviroturf (or a similar species of grass), this would save between 75–90% of the water that’s currently used to water lawns. In other words, if every lawn made the switch, it would save between 2.8 and 3.4 million acre-feet: close to half the amount California is short! All without sacrificing lawn aesthetics or personally inconveniencing people. It would also have the advantage of making California further resistant to future droughts.

This is great, but even if implemented across the board only solves about half of the problem. Other options…

Idea #3: Install Ocean-based Solar Stills off the Coast of California

This one is a bit on the crazier side.

A solar still is a device that allows you to distill (hence, the “still”) fresh water from saltwater. It works by using the solar heat from the sun to evaporate saltwater and then capture the resulting evaporated freshwater. You can get a rough idea for how this works below:

Theoretically, you should be able to float devices like the above on ocean water and collect the resultant freshwater. The output of a solar still is 0.61 gallons per square meter per day. So, in order to produce just 1 acre-foot of water using solar stills, you’d need to cover 534,182 square meters of ocean water with solar stills. In order to make up the 6 million acre-foot shortage, you’d need to cover 3,205,092,000,000 square meters of ocean water… or 1.158 square miles. That’s about the size of the town of Miles, Iowa, or about 1/400th of the San Francisco Bay.

The largest cost to implement this would be collecting and transporting the fresh water. The cost for pumps and hoses, transporting the water to land and then shipping it to where it’s needed would be the most expensive part of this operation, not to mention the ~$86 million you’d spend on plastic to build the things.

The only way I could see this working (given prohibitively expensive cost to collect and transport water) would be setting up a farm of solar stills on the surface of a river delta or estuary, and just letting the new freshwater flow into California’s river system, where it would then replenish the rivers and streams that are currently taxed beyond capacity. This way, freshwater would make its way into the California ecosystem, and you wouldn’t have to worry about collecting freshwater from each individual solar still.

That’s one option that could work. And, though expensive, when it comes to ensuring the Golden State doesn’t become a brown one, California’s annual budget is $113 billion. If this seems like a feasible option, the funding is probably there.

So that’s solar stills. After doing a bunch of research and wracking my brain, I could only think of three more…

Idea #4: Set up Reverse Osmosis Desalination Plants

This experiment is currently going on in San Diego, with the construction of a $530 million dollar desalination plant. Just a single one of these plants can produce 5–10% of San Diego’s annual water supply.

The trouble with these plants is that they’re expensive. Not only is it expensive to build the plant in the first place, but it’s expensive to operate. Take another look at our graph from earlier — you can see that water from RO plants is far more expensive than water from almost any other source.

The expense problem is very real. After all, California won’t always be in drought conditions. The only reason we’re in this hot mess is due to a black-swan combination of near-zero snowfall and very little rain.

What that means for RO plants is that as soon as California is no longer experiencing a drought, it will stop using RO plants as a water source. This is exactly what happened in Santa Barbara after they went through a drought: things returned to normal, and they shut the plant down.

Ok. So building a RO plant, on top of being extremely expensive, likely wouldn’t be used 5–10 years from now when conditions (presumably) return to normal. Let’s take a look at our last two options.

Idea #5: Poison All Alfalfa Crops!

Well, not really. But not far off.

You see, the alfalfa industry in California uses about 5.3 million acre-feet of water per year. That’s more than double the amount of water used by almond farmers, and almost double the amount of water used by each of the 40 million people in California in a given year.

Scott from Slate Start Codex put it best in his article:

The California alfalfa industry makes a total of $860 million worth of alfalfa hay per year. So if you calculate it out, a California resident who wants to spend her fair share of money to solve the water crisis without worrying about cutting back could do it by paying the alfalfa industry $2 to not grow $2 worth of alfalfa, thus saving as much water as if she very carefully rationed her own use…

Cutting water on the individual level is hard and expensive. But if instead of trying to save water ourselves, we just paid the alfalfa industry not to grow alfalfa, all the citizens of California could do their share for $2. If they also wanted to have a huge lush water-guzzling lawn, their payment to the alfalfa industry would skyrocket all the way to $5 per year.

So. That seems promising. Though, at that price level, implementing an effective anti-alfalfa-growing campaign is unlikely to be done by the citizenry. We’d need a government tax or intervention, and I’m sure there’d be plenty of pushback from the eminently powerful alfalfa lobby industry. I don’t know how likely it is that this happens, but my guess is that it’s low. So, even though doing something to curb alfalfa’s water usage would have a big impact, I’m not sure what that something would reasonably be.

Other than burning their crops with fire, that is. This brings us to our last option…

Idea #6: Recycle and Reuse Wastewater for Agriculture

Over the course of researching this post, I did a lot of reading about countries in the Middle East: literally, countries that exist in the desert.

A commonality among many countries in drier parts of the world is their use of water recycling techniques, especially in agriculture. For example, according to this article…

Israel has, in the meantime, become the world leader in recycling and reusing wastewater for agriculture. It treats 86 percent of its domestic wastewater and recycles it for agricultural use — about 55 percent of the total water used for agriculture… the United States recycles just 1 percent, according to Water Authority data.

This seems promising. Israel gets more than half of all the water used for agriculture from treated domestic wastewater, while the US recycles just 1% of all wastewater.

The US has 9 million acre-feet of water used for lawns, individual consumption and industrial uses. At current rates, that means that we’re recycling roughly 90,000 acre-feet of wastewater per year.

However, if we were to treat just 66% of the water used for urban consumption, we’d easily close the 6 million acre-foot shortage that’s causing the California drought. What are our options for treating wastewater? From Wikipedia:

The plant, known locally as Shafdan, was lauded for its unique method of using the natural filtration qualities of sand to improve the quality of sewage. In 2010, about 400 million cubic metres/year of treated wastewater was reused, primarily in agriculture. This constitutes about 40% of water use in agriculture.

Again, building plants like these are expensive. However, unlike an RO plant that becomes unnecessary once drought conditions evaporate, a wastewater treatment plant will always be useful, as is reclaims water at a lower cost than other desalination processes.

I also found another way to treat wastewater, that simply requires somewhat larger tracts of land but no plant buildup: stabilization ponds. According to a world study, stabilization ponds are one of the most cost-effective methods for treating wastewater, as the only cost associated with their operation is the allocation of land.