I don't fully agree with this statement, it's more that you're not just affecting your rainfall, but neighbors as well. As we speak, 8 of the Western states in the US are performing scientific trials together.
There's no hard data that shows exactly how much weather modification actually works. Some data shows 5 to 15% increased snowfall, but that's just statistical analysis. Once we get hard data that shows the cost/benefit, you're likely to see more weather modification efforts (e.g. how many dollars per acre-foot of water? Is this cheaper or more expensive than pipelines, or drinking water reservoirs? What would a budget look like for bolstering our agriculture? Can a state government budget a few million for the next year due to an anticipated reduction in rainfall? How many million would we need? What's the human and ecological (particularly beneficial bacteria and algae) impacts of being exposed to AgI?)
We also don't know how wide-scale it works. Yes, China can seed clouds to reduce smog to have blue skies for PRC meetings in Beijing, but can it work on the scale of say, an entire mountain range? Or the agricultural area of an entire state? Can't say. It's only been in the last few years that we've gotten RADAR and compute that's capable of analyzing our experiments.
Also another thing, you can generate precipitation, but even weather modification technology can't overcome a drought. If you have a high pressure system (like the one currently sitting over most of the West US at the moment) you're stuck with dry skies.
California has an agriculture problem.
* Since 1987, the United States has been the largest producer of almonds worldwide. The success of the California crop in seizing the No. 1 rank in world almond production is due in large part to the use of irrigation and mechanization, resulting in higher yields and cost effectiveness.
The US produces 10x more almonds than number two on the global biggest exporters list: over 2m tons/year, #2 on the list is Spain with 200k tons. California is the #1 producer of almonds in the world. It takes 1.1 gallon of water to grow one(!!!) almond.
https://www.atlasbig.com/en-in/countries-by-almond-productio..., https://keepcaliforniafarming.org/produce/california-almonds..., https://www.paesta.psu.edu/podcast/how-much-water-does-it-re...
Look at page 4: https://www.cdfa.ca.gov/statistics/PDFs/2017-18AgExports.pdf
Pistachios, walnuts, dairy, wine, beer, kiwis(!), avocados, grapes, rice!
To be fair, we had big, honkin', town-killin' fires back when it rained and snowed more than average for decades.
It's hard to tell how much is due to drought, how much to a shift from snow to rain, how much is home development, how much is homeless people torching off areas (more than you'd like to think).
So, maybe you're referring to an earlier period, in which case, cool.