1. Agriculture uses way more water than cities, but not necessarily 80 percent.

We hear all the time that growers use 80 percent of California's water. And state officials do say California's 9 million acres of farmland consume that much. But that's 80 percent of human water use.

Cities and towns account for the rest. For a long time, that was the dominant way of tallying the state’s water use. But state officials now count environmental uses for water, too:

So, with those uses, the total water budget has grown. The breakdown now:

Wild and scenic rivers protected under federal law get 31 percent.

In other rivers, we keep water flowing at a certain rate for recreation, environmental reasons or both. Maintaining such “instream flows” takes around 9 percent.

Keeping seawater out of the Sacramento-San Joaquin River Delta — the source of much of the state's drinking water — uses about 7 percent.

Managed wetlands get 2 percent.

Cities and towns get 10 percent.

What that means is that agricultural irrigation accounts for around 41 percent of the state’s water pie.

The Public Policy Institute of California helpfully shorthands that to: 50 percent environmental, 40 percent agricultural, 10 percent urban.

But Jeffrey Mount at UC Davis’ Center for Watershed Sciences says that’s all wrong. He argues the state’s accounting system is misleading and should leave out wild and scenic rivers, since it’s impractical to get water out of them for any kind of human use.

He says the right water pie includes net usage of water from California’s interconnected river and aqueduct delivery systems. By his accounting, agriculture gets 62 percent, urban water users 16 percent, and environmental purposes 22 percent.

2. Farms and cities mostly get their water from the same place.

The federal government and the state both operate a system of reservoirs, aqueducts and canals that capture rain and snow melt and sell that water to farms and towns.

The federal Central Valley Project's primary source is Lake Shasta (actually a dammed reservoir), and it mostly provides water to farms in the San Joaquin Valley. The California-run State Water Project draws most of its water from Lake Oroville (also a reservoir) and ships most of it to farms and cities in southern part of the state.

But during the drought, water allocations to farms have regularly been cut back, sometimes significantly.

3. Farms are relying on groundwater more and more.

To make up for curtailed surface deliveries, farmers have pulled more water out of the ground. Farmers use some groundwater even in wet years to irrigate their crops, but the thinking is those supplies will be replenished in wet years.

In dry years, that groundwater can make up as much as 46 or even 60 percent of supplies, and little precipitation means little replenishment.

California was, until recently, the only state without a comprehensive statewide groundwater management plan.

Some places are doing better than others at managing groundwater. But it’s pretty spotty, and a lot of local plans lack goals or standardized definitions for what is sustainable.

Bottom line: we know we’re using more than we should. But we don’t know how much.

4. California's first-ever groundwater law will take years to implement.

A law passed in 2014 requires better planning. But that planning is complex.

The law requires groundwater planning for sustainability, but gives a very long timeline for achieving it — around 30 years. Getting strict limits in place, and a definition for sustainability, will itself take years.

The planning process is unlikely to be completed in time to limit the impacts of the most recent drought's groundwater overdrafts.

5. Prices for farm water can vary widely.

Water prices for farmers can be cheap. They are often offered a discounted rate for water they purchase through the federal Central Valley Project.

In 2005, the Environmental Working Group estimated that the yearly subsidy farmers got from buying water through the CVP amounted to $60 million.

But farmers also need water when they need it. You can’t take a year off from tree nuts and stone fruits. And as it becomes more scarce, water gets way more expensive. In 2013, the Westlands Water District paid $140 an acre-foot of water. In 2014, that price soared to $1,100.

What's more, the price of digging groundwater wells has risen as aquifers are drained and farmers need to sink even deeper wells to access the groundwater.

6. Farmers plant almonds because we (the consumer) demand them.

Farmers aren’t the kind of people who buy Uggs just because the paparazzi caught a celebutante wearing them at LAX. And they didn’t just plant almonds because they’re trendy. High dollar-value crops are getting more common because they’re worth it to farmers. And almonds have gotten a lot more common in a relatively short time: Since the early 2,000s, they've tripled in production.

Farmers are also making use of newer technologies. Drip irrigation is catching on because it helps farmers improve their yields.

Farmers think of almonds as a 25-to-30-year investment. Along the way, they’ll take a lot of steps to keep that investment safe.

7. The Bay Delta, heart of California's water system, is stressed out.

Almost half the state’s water flows through the Sacramento-San Joaquin River Delta (often shorthanded to "Bay Delta"). It's an estuary that is more than 1,100 square miles and ranges over five counties.

Water from the rivers flows through Suisun Bay into the Delta region, where the fresh water mixes with seawater from the ocean. Water in the Delta either flows back out to the ocean through San Francisco Bay or gets exported to Sacramento and cities around it or to farms and cities to the south.

Over time, California has been pulling more water into use – and that’s changing the mix of salt and fresh water in the estuary. That’s made the Delta vulnerable to invasive species, habitat degradation and loss and disappearing wetlands.

Also, sea-level rise connected to climate change pushes salt water further into the delta, increasing pressure on subsiding levees and worsening the other environmental problems.

None of this is new, and since 1994, a joint state-federal program called CALFED works to improve levees, protect water supplies and restore a failing ecosystem. Fourteen state entities, an equal number of federal ones and various Native American tribes are part of the effort.

8. The Delta Smelt is the canary in the Bay Delta.

The smelt is both a 2-to-3-inch-long silver fish and a symbol. Environmentalists say it’s one of the best indicators of the health of the Delta, and what it’s indicating isn’t good, especially since just 12 of 29 fish species endemic to the region still exist there.

Under the federal Endangered Species Act, the smelt are a threatened species. Farmers see it as an enemy, since water supplies they use for crops are frequently curtailed to maintain river and estuarine flows in the delta.

9. Many farmers and their supporters see the drought as 'Fish vs. People.'

Maybe you heard Carly Fiorina make this argument in Time, about how the Bay-Delta is being managed:

Specifically, these policies have resulted in the diversion of more than 300 billion gallons of water away from farmers in the Central Valley and into the San Francisco Bay in order to protect the Delta smelt, an endangered fish that environmentalists have continued to champion at the expense of Californians. This water is simply being washed out to sea, instead of being channeled to the people who desperately need it.

Fiorina argues that 70 percent of California’s water washes out to the sea.

But the California Water Foundation, a non-partisan water policy think tank, disagrees, saying that the number is closer to 50 percent. And that includes water in the far northern part of the state dedicated to rivers designated "wild and scenic": water that would not otherwise enter the projects delivering supplies to cities and farms.

10. 'Fracking' uses a fraction of the state's water.

Reuters has reported that, according to California officials, oil and gas operations used 214 acre-feet of water in the process of hydraulic fracturing. That’s the equivalent of 70 million gallons, or what 514 California households need for a year.

But it’s also worth pointing out that those operations bring 387,000 acre feet to the surface. That’s because two-thirds of that water goes back into aquifers, and a third of it is cleaned up, or injected into the ground or evaporated.

Investigations about how state regulators are overseeing the disposal of that wastewater (and admissions by the regulators themselves) have revealed problems with the state’s oversight of this water.

In 2014, the EPA issued emergency closure orders for 11 injection wells, most of which were illegally dumping wastewater in groundwater aquifers meant to be protected.