Water can be a real point of contention in California, a state that has over the past few decades been taken on a wild rollercoaster of drought and surplus rainfall. People are passionate about water, and for good reason; we need it to grow food and to live, among a myriad of other uses. Fortunately for our county, a weather modification technique that sounds like something from a spell book could help buffer farms against future drought.

That’s good news for Talley Farms, a family-owned business in the Arroyo Grande Valley that’s been producing food since 1948. Grown on the 1,500-acre property are 30 different kinds of vegetables and fruits like blackberries, raspberries, strawberries, lemons and avocados. About 129 acres are dedicated to growing wine grapes. “This is one of the best places in the world to farm for the things that we do, and we need supplemental water for all of that,” says Talley Farms President and CEO Brian Talley.

Some parts of the year, Brian relies on natural rainfall to grow his crops. But the rest of the year, access to groundwater is pivotal. The groundwater Talley Farms uses comes from Lopez Lake.

“We are blessed with a fairly shallow and rapidly recharging aquifer under the Arroyo Grande Valley; that means, as long as there’s water there, it’s pretty cheap to pump out,” he explains.

At the time of this writing, the lake’s reservoir was at 100 percent capacity, but that’s not always the case. “The issue that we were dealing with in the drought that persisted before the rains of 2023 was that Lopez Lake had reached its lowest level basically in its history, since the time that the dam was constructed back in 1969,” says Brian, referring to January 2023 when the lake fell below 25 percent capacity.

Brian holds a seat on the Zone 3 Advisory Committee, a group of representatives from all of the communities that receive water from Lopez Lake. Committee members include residents from Arroyo Grande, Grover Beach, Pismo Beach, Oceano and the Avila Beach Community Services District.

“We were becoming concerned that downstream releases were going to be curtailed to such an extent that it would really affect that aquifer,” explains Brian. “We were talking all the time about what’s the best way to get more water into this system, more water behind that dam, so that we can continue to release water into the Arroyo Grande Creek.”

After weighing options, it turns out an unlikely savior to San Luis Obispo County’s potential water woes was hovering in the clouds above: cloud seeding. Explaining how cloud seeding works sounds like a fever dream, but David Spiegel, Supervising Engineer for San Luis Obispo County, puts this meteorology magic into layman’s terms.

“[The way it works is] silver iodide is released into the clouds. What that does is it allows the cells to nucleate — the water and vapor wrap around those little particles — and increase cloud density,” explains David. “The idea is to increase the production of water that’s already there, essentially trying to squeeze more water out of a cloud. So, you’re not actually making any more water, you’re just trying to get more water out of it.”

But how do the silver iodide particles reach the clouds, and who places them? David says the particles are put into a flare, by North American Weather Consultants (NAWC), that burns and releases them into the atmosphere. While the sky may seem endless, the clouds they target can be very precise.

“The science is pretty sound with how long it takes those particles to nucleate and then drop out as either ice or rain,” says David. “[We] can look at storms and their trajectory and speed, and know where [we] need to release those particles to really target a specific area. And for us, we target the Lopez watershed in our cloud seeding operations.”

Water from the watershed gets drained out into Lopez reservoir which provides water for three sources: municipal agencies, the creek and agricultural land. “In addition to that water going down the stream, it’s also recharging the groundwater basin, which allows our agriculture industry to pump that groundwater,” describes David.

And cloud seeding has become one of the more cost-effective water solutions for the county, compared to using state water that Brian says can cost up to $1,000 per acre foot. An acre foot is about 326,000 gallons, which is enough water to cover one acre of land, about one foot deep.

“Depending on whether we do ground base seeding or air-based seeding, our program can run anywhere from about $150,000 up to $350,000 per year,” shares David. “The way we see it is, if you can produce 1,000 extra acre feet of water by cloud seeding, then that water essentially costs about $300 per acre foot. And that’s really inexpensive water.”

To mitigate concerns about who gets this water, county leaders adopted an interim downstream release schedule that dictates how it will release water out of the reservoir for environmental purposes and sets the stage for what agricultural sites can use as well.

“In my experience, people become more passionate about it during droughts — they get very concerned about our lack of adequate water supply,” says Brian. “Once we get to a point where we’re out of the drought, people kind of forget what a precious commodity it really is. Here at Talley Farms, my father took a real leadership role in water conservation and we have continued to embrace that, most notably through the widespread use of drip irrigation throughout all of our operations, which means we deliver water much more efficiently and conserve a lot of water compared to older irrigation technologies.”

Since the cloud seeding program began in 2020, the county has approved an operations plan that assigns roles and responsibilities for NAWC, as well the county. The plan lays out areas of concern, like the levees in Oceano that are prone to flooding.

“The plan allows the [Flood Control District] to suspend seeding operations at any point in time — no questions asked — based on creek levels, immediate flooding, weather announcements that say that there’s going to be flooding, et. So, we really do monitor all the weather reports, the National Oceanic and Atmospheric Administration reports and all our stream gauges, to try to stay on top of understanding how the weather is coming at us and if it’s responsible to seed or not,” David shares.

In fact, as of press time the program was on pause due to the massive amounts of rain San Luis Obispo County received in 2023. David says the reservoirs have been too full and the last thing the county wants to do is increase the spill volume, which would send water down the spillway. While the program isn’t in use at the moment, David says the county plans to keep it as a tool for times of drought. That safety precaution is promising for farmers like Brian.

“I think we are blessed with a progressive group in our county that seems to be committed to supporting agriculture,” Brian says. “I appreciate the collaborative approach that we have to work together to make San Luis Obispo County such a special place.”