In the powerhouse food bowl of California, the impact of its most recent drought — which finally ended in 2017 after eight gruelling years — continues to be felt across the sunshine state.

Key points: The 2011-2017 Californian drought cost the US economy $AU5.6 billion

The 2011-2017 Californian drought cost the US economy $AU5.6 billion The drought exposed deep problems with water management and access across the state

The drought exposed deep problems with water management and access across the state Some Californian farmers are looking to how Australian farms survived droughts this century

Farmers, experts and lawmakers are working to find more sustainable ways to droughtproof farms and address the vexed issue of water allocation.

And it turns out many farmers and water experts in California are looking to Australia for answers as they face up to the biggest water reforms in the history of the US.

When California's worst drought in history ended in 2017, it cost the country $US3.8 billion ($AU5.6 billion) and exposed deep flaws in its water management processes.

"Being a life-long Californian, I've seen the population increase, but we haven't increased our ability to hold water as our cities get bigger and the demand for water increases," said Keith Bungo, a strawberry farmer from Salinas Valley, one of the state's most productive agriculture regions.

Last year, California produced $US50 billion ($AU74 billion) in food for the economy — 13 per cent of the nation's entire agricultural output.

The massive network of dams, pumping plants, hydro-power stations, and hundreds of kilometres of canals and pipelines of the California Water Project makes this happen.

Forty per cent of all water goes to irrigate 3.6 million hectares of crops.

But at the height of the drought in 2014, with no surface water to call on, agriculture was given zero water allocation in some catchments.

Farmers could either buy water at an exorbitant rate or excessively pump groundwater. It's estimated 5,000 new wells were drilled.

Some of the produce from the Salina's Valley to be exported to Japan. ( ABC News: Owain Stia-James )

At Bowles Farms, the owners are sixth-generation farmers. They grow cotton, tomatoes, vegetables and herbs on their 4,500 hectares using drip irrigation and employ up to 600 people during peak season.

"We did drill some additional wells just to try to protect ourselves," executive vice-president Derek Azevedo said.

"We are very fortunate in this part of the state; we have very good groundwater supplies and the pool of water we are towing from is rechargeable."

'Crop per drop'

Sustainability and innovation have been Bowles Farms' focus in recent years. They have a solar farm and drones to detect water leaks and monitor soil sensors.

Mr Azevedo says data is now a driving force when it comes to water management.

"Farming exists today because of advances in technology and irrigation, he says.

"We've had the opportunity to advance to not only have really high-quality flood irrigation, but also in recent droughts invested heavily in drip irrigation and sub-surface drip irrigation [to try to] optimise the value of the water we use and think about more crop per drop."

In a normal year, groundwater supplies 40 per cent of the requirements for farms and communities but during the drought it soared to 60 per cent, and in some places it was 100 per cent.

It was not without consequence, and the full picture is only now being revealed. In the San Joaquin Valley, the groundwater is over-allocated by 17 per cent.

Ellen Hanak, from the Public Policy Institute of California, said that this could lead to decreasing water quality, land sinking and, of course, wells drying out.

The policy research institute has completed one of the most comprehensive papers on how the state can replenish its overtaxed aquifer system.

It has found that in some places drilling has caused the land to sink by as much as 7 metres and is still sinking.

Californian farms produce a significant proportion of the US's fresh food. ( ABC News: Kristy O'Brien )

"The tough thing is that's one of those things that has a delayed reaction, so even now when we've had a few good years, the land is still sinking," Ms Hanak said.

Cracks and holes are forming in roads and in the worst cases sinking land can trigger the release of arsenic into the water, making it dangerous to drink.

New water laws

Changes are needed and that is why reducing groundwater use will soon become law.

Under the Sustainable Groundwater Management Act, local agencies in California will have until January 2020 to develop regulations to limit groundwater pumping and shut down wells.

Once agreed, they will have 20 years to put those plans into action. If it does not work, the consequences could be brutal.

"We estimate in the San Joaquin Valley that at least half a million acres are going to come out of irrigated crop land over the next 20 years as part of the implementation of this law," she said.

"It could be more if folks are not successful at maximising groundwater recharge."

William Bourdeau is one those directly in charge of coming up with solutions. He manages Harris Farms, which was formerly one of the biggest beef feedlots in the state. He is also on the district's water board that covers 500 family farms across 240,000 hectares.

"It was only until they cut off our surface water that we started over-drafting," he said.

"I'm sure we can overcome this and we won't have to overdraft the aquifer; let's use that only when it's absolutely necessary."

The Australian connection

Kevin France is also offering up a way of protecting the allocations that farmers have. He is part of the Western Growers Association Center for Innovation in the Salina's Valley and is essentially a water accountant.

He developed an "accurate, actionable and auditable data" system in conjunction with the US Department of Agriculture, which also has the backing of two Australian investors.

"You're talking about the livelihoods of the legacy generations of growers that are for the first time in their history looking at the real distinct possibility that they might have to go out of business and not provide food security for the country," he said.

"It's a serious problem."

He said Australia was offering some sound examples of how to proceed.

San Luis Dam is full again after good rain and snow this year, with 55 per cent going to the state and 45 per cent to the federal government. ( ABC News: Owain Stia-James )

"We saw what happened in Australia and saw the writing on the wall. In some regards, Australia went through exactly what's likely going to happen in the United States," Mr France said.

Building more dams to store water is often touted as a solution, particularly during big rain and snowfalls. But the world's largest agriculture lender Rabobank is quick to point out the costs and controversy involved.

"Currently there are over 1,400 dams in California [and] most of that infrastructure … is over 50 years old," senior analyst Roland Fumasi said.

"I get the question all the time — 'why hasn't more been done to increase the ability to store water during wetter years?'. The short answer is there's been a lot of environmental push back [against] new water infrastructure.

"[It's] seen as an impediment to the natural environment and the environmental regulations in California have actually been probably the largest hindrance."

He supports the idea that California must look to the driest inhabited continent on Earth for fresh ideas.

"Australia has some major resource constraints, just like California," he said.

"Australia has made some strides in developing its water resources and … I think in California, we've got similar challenges.

"I think Australia can be a great country to learn from as we continue to make our water situation better."

Major droughts certainly hurt, but also historically have led to major innovations and reforms, not just at legislative levels, but directly on farms, too.

These Californians know it is going to be tough but necessary for them to make changes to continue to toil on the land they love.

"I firmly believe we are at a point in our time that we can solve these problems," Mr Bourdeau said.