You might not feel it while you’re drinking your morning coffee in Red Bluff or driving out past Corning, but the earth is moving. Not in the "earthquake" kind of way, but in a slow, silent, and frankly expensive way. The dirt is dropping. It’s called Tehama County land subsidence, and honestly, it’s one of those problems that feels invisible until your well goes dry or your irrigation canal starts flowing backward.
Groundwater is basically the lifeblood of the North Valley. When we pump too much of it out during droughts—which, let’s be real, are becoming the "new normal"—the spaces between the underground silt and clay collapse. Think of it like a sponge. When it’s wet, it’s plump. When you squeeze all the water out and let it dry, it shrivels. The catch? You can’t just "re-wet" the ground to make it pop back up. Once that clay collapses, that storage space is gone forever.
It’s a permanent loss of infrastructure.
The Reality of Tehama County Land Subsidence Today
Most people think land subsidence is a San Joaquin Valley problem. You’ve probably seen those famous photos from the 1970s of Joe Poland standing next to a telephone pole showing where the ground was 50 feet higher back in the 1920s. We aren't seeing 50-foot drops in Tehama County yet, but the California Department of Water Resources (DWR) has been tracking some concerning shifts. In certain pockets of the county, specifically near the borders of Glenn and Colusa, the land has dropped several inches in just a few years.
That might sound like nothing. "Oh, two inches? Who cares?"
Well, gravity cares. Water infrastructure cares. If you have a massive irrigation pipe designed to run on a 1% grade and the middle of the field sinks three inches, that water isn't going where it’s supposed to go. You end up with standing water where you don't want it and bone-dry crops where you need them.
The Corning Subbasin is particularly under the microscope right now. Because this area relies so heavily on the Tehama-Colusa Canal and local groundwater, the pressure on the aquifer is intense. During the 2012-2016 drought, and again in the early 2020s, pumping surged. When the rain doesn't fall, the pumps stay on. It’s a simple, brutal math problem.
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Why the Geology Here Makes It Worse
It’s all about the clay. Tehama County sits on a mix of sediments washed down from the mountains over millions of years. Some layers are gravelly—these are the good ones because they hold water and don't collapse easily. But then you have the fine-grained silt and clay layers.
When the water pressure in those clay layers drops, the weight of the soil above literally crushes the layers flat. This process, known as "aquitard compaction," is the primary driver of Tehama County land subsidence. It’s not just a surface issue; it’s a structural failure of the geological layers hundreds of feet down.
SGMA: The Law That Changed Everything
Back in 2014, California passed the Sustainable Groundwater Management Act (SGMA). For decades, if you owned land, you basically had a "Wild West" right to pump whatever was underneath you. SGMA ended that. It required local agencies to form Groundwater Sustainability Agencies (GSAs).
In Tehama, we have the Tehama County Flood Control and Water Conservation District acting as the GSA for several subbasins, including Antelope, Bowman, Los Molinos, and Red Bluff. Their job is basically to make sure we don't pump the county into a hole.
But here's the kicker: they have to reach "sustainability" by 2042. That sounds like a long way off, but the plans they are writing right now—Groundwater Sustainability Plans (GSPs)—are already changing how farmers and residents use water. If the data shows that Tehama County land subsidence is accelerating in a specific area, the GSA has the power to limit pumping. That’s a massive deal for property values and the local economy.
The Human Cost of a Sinking Landscape
It isn't just about big ag. If you're a homeowner with a domestic well, subsidence is your enemy. As the ground compacts, well casings can literally buckle or snap. I've heard stories of people whose well heads are suddenly sticking out of the ground higher than they used to be. The well didn't grow; the ground around it sank.
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Then there’s the issue of "losing" the aquifer. Once that ground collapses, it can no longer hold water. Even if we have a "miracle march" with record rainfall, that underground storage is gone. It’s like breaking a jar; you can't put the water back in it once it's smashed.
What Most People Get Wrong About Subsidence
A common misconception is that if we just stop pumping today, the sinking stops tomorrow. It doesn't. There’s a "lag time" in the geology. The deeper clay layers can continue to compact for months or even years after groundwater levels have stabilized.
Another myth? That it’s all the "big corporate orchards" to blame. While large-scale nut crops definitely use a lot of water, the issue is systemic. It's a combination of climate change, reduced surface water deliveries from the Central Valley Project, and a historical lack of oversight. Everyone—from the hobby farmer with five acres to the massive operations—is drawing from the same straw.
Measuring the Invisible
How do we even know it’s happening? DWR uses some pretty cool tech called InSAR (Interferometric Synthetic Aperture Radar). Satellites bounce signals off the ground to measure elevation changes with millimeter precision.
When you look at the InSAR maps for the Sacramento Valley, Tehama County used to be "green" (stable). Over the last decade, we've started seeing more "yellow" and "orange" spots. These are the areas where the ground is dropping by 0.1 to 0.2 feet per year. It’s a slow-motion disaster.
Actionable Steps for Property Owners
If you live in Tehama County, you can't just ignore this. Whether you're worried about your home's foundation or your orchard's longevity, there are things you should be doing right now.
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Monitor Your Well Levels
Don't wait for the pump to start sucking air. You should be tracking your standing water level at least twice a year—once in the spring when it's highest and once in the fall after the heavy pumping season. If you see a multi-year downward trend, your area is at higher risk for subsidence.
Check Your Infrastructure
Walk your property. Look for new, unexplained cracks in concrete pads, tilting fence lines, or doors that suddenly don't close right. In agricultural settings, watch for changes in how water flows in your ditches. If a spot that used to drain perfectly is suddenly a pond, the ground might be shifting.
Get Involved with the GSA
The Tehama County Groundwater Sustainability Agency holds public meetings. Go to them. These are the people deciding who gets to pump what. If you aren't at the table, you're on the menu. You can find their meeting schedules on the Tehama County Public Works website.
Invest in Recharge
"On-farm recharge" is the big buzzword. If you have extra surface water during wet years, find ways to let it soak into the ground instead of letting it run off into the creek. Some farmers are even flooding their orchards in the winter to help "refill the bank."
The Long View: Can We Fix It?
Honestly? We can’t "fix" the subsidence that has already happened. That land is down for good. But we can stop it from getting worse.
The future of Tehama County depends on a delicate balance. We need the agriculture—it’s the backbone of our local tax base and jobs. But we also need a stable surface to build on. If we keep mining groundwater like it’s an infinite resource, the infrastructure costs of repairing broken canals, roads, and bridges will eventually outweigh the profits from the crops.
We are currently in a transition period. The "Wild West" of water is over. Moving forward, the counties that manage their subsidence risks the best will be the ones that remain economically viable. Those that ignore the satellite data and keep pumping blindly? They’re literally sinking their own future.
Practical Next Steps to Protect Your Land
- Verify your subbasin: Check the DWR SGMA Portal to see exactly which groundwater subbasin your property sits in and read the specific "Annual Report" for that area to see the latest subsidence measurements.
- Inspect well casings: Have a well professional do a video inspection if you suspect your well is failing; early signs of casing "pinching" can sometimes be addressed before the well is a total loss.
- Diversify water sources: If you are 100% dependent on groundwater, look into the feasibility of securing surface water rights or participating in local water transfers during dry years.
- Support local storage projects: Projects like the proposed Sites Reservoir, while controversial to some, are designed to provide the surface water buffer that reduces the need for groundwater pumping during droughts.
- Update your land surveys: If you are planning major construction or irrigation overhauls, don't rely on 20-year-old elevation data; get a fresh survey to ensure your grades are still accurate.
The ground is changing, and our approach to water has to change with it. Staying informed isn't just about being a "good citizen"—it's about protecting the literal foundation of your home and livelihood. Keep an eye on the maps, watch your well, and stay vocal in local water politics. The era of taking the dirt beneath our feet for granted is officially over.