Drive south from Coachella on Highway 111 and the smell finds you before the water does — a low sulfur tang off the exposed flats, strongest on a hot afternoon when the wind comes off the playa. Then the Salton Sea opens up on your right: California's largest lake, 227 feet below sea level, ringed by a pale crust of dry lakebed that gets wider every year. Locals call it the bathtub ring. It is the receipt for a decision made 200 miles upstream.
The Salton Sea is drying because the water that kept it alive was never a river or a spring — it was agricultural runoff. When the Colorado River got "saved" through conservation and transfer deals, that runoff was rerouted to cities, and the sea it had sustained for a century began to collapse. This is the cost of conservation that no program has ever put a price on.
If you searched "why is the Salton Sea drying up," here is the honest answer, in one paragraph, before anything else.
the short answer
The Salton Sea is an accidental lake. In 1905, Colorado River floodwaters broke through an irrigation canal and poured into the Salton Sink for 18 months. What should have evaporated away instead stayed full — because for the next century, farms in the Imperial, Coachella, and Mexicali valleys drained their irrigation water into it. The sea was, in effect, plumbed to agriculture. It shrinks now for one reason: it is getting less of that drainage. Less water to the farms upstream, and less runoff, means a lower sea, a wider exposed lakebed, and toxic dust blowing into some of the poorest communities in California.
That's the whole mechanism. The rest of this piece is why it happened, who is paying for it, and why the cost was invisible on every ledger that mattered.
the lake that runoff built
Stand on the north shore near the old Torres-Martinez tribal lands and it's hard to picture, but this water body is younger than the state highway that reaches it. The Salton Sea has no natural inflow. Its two main feeders — the Alamo River and the New River — are essentially agricultural drains, carrying spent irrigation water off Imperial Valley fields and, from the south, out of Mexicali.
That plumbing is the whole story. A $2 billion-a-year farm economy irrigates with Colorado River water delivered through the All-American Canal; whatever the crops don't drink runs downhill into the sink. For a hundred years, that return flow roughly balanced evaporation, and the sea held. The Salton Sea is not a natural lake that we failed to protect. It is a byproduct of irrigation that we quietly depended on — a nursery on the Pacific Flyway and a buffer keeping a century of farm chemicals safely underwater.
the deal that saved the river and starved the sea
In 2003, seven states signed the Quantification Settlement Agreement (QSA) — often called the largest agricultural-to-urban water transfer in U.S. history. The Imperial Irrigation District agreed to conserve water and send it to San Diego and Coachella instead. On the Colorado River ledger, this was a win: water "saved," cities supplied, pressure eased on an over-allocated river. It is exactly the kind of conservation the whole basin is now scrambling to do more of.
Here is the part the headlines skipped. Conserved irrigation water means less irrigation runoff. Less runoff means less water reaching the Salton Sea. The negotiators knew this, so the QSA included 15 years of "mitigation water" — deliveries meant to keep the sea propped up while the state built a restoration plan.
That mitigation water ended on December 31, 2017.
The sea responded immediately. Shoreline retreat, running at about 12.5 meters a year from 2002 to 2017, tripled to roughly 38.5 meters a year after 2018. The lake now drops about a foot annually. Salinity has climbed past 60 grams per liter — nearly double the ocean — collapsing the tilapia the birds feed on. Every foot the water drops uncovers more lakebed. And that lakebed is not clean.
the dust, and who breathes it
Imperial County already has childhood asthma rates above 20 percent — roughly double California's average. A 2025 UC Irvine study tracking kids in the surrounding towns found a direct link between dust exposure and declining lung function. The communities downwind — North Shore, Niland, Calipatria, Westmorland, Bombay Beach — are more than 85 percent Hispanic, many of them farmworker families, with a median household income around $47,000. They did not sign the QSA. They did not get the transferred water. They get the dust.
Think about what that means as a chain of decisions. A grower conserves water and is paid for it. A city 200 miles away turns on the tap. And a child in Calipatria reaches for an inhaler on a windy afternoon. Every link in that chain shows up on someone's books — the conservation payment, the urban water bill — except the last one. The asthma is real. Its price, on every ledger that governs the river, is zero.
And it isn't only people. With 95 percent of California's wetlands already gone, the Salton Sea has become one of the most important bird stops in the West — 433-plus species use it. Nearly all of California's eared grebes pass through. So do a third of North America's white pelicans. It is the only reliable place in the United States to find the yellow-footed gull. As the sea turns too salty for fish, that flyway node blinks out too — another cost no invoice captures.
the externality nobody prices
Here is the uncomfortable turn. Everything that dried the Salton Sea was, by the river's own rules, the right thing to do. Conserving water in an over-allocated basin is the goal. San Diego needed a firmer supply. The Imperial Irrigation District holds the single largest entitlement on the river and used it to strike a deal the whole basin held up as a model. No villains — just a win that quietly pushed its cost onto people and birds who weren't at the table.
Economists have a word for a cost that lands on someone outside the transaction: an externality. The dust off the Salton Sea is a textbook one. And the reason it keeps growing is that no one whose decision creates it has to carry it on their books. The conservation deal priced the water. It never priced the runoff the sea depended on, or the lakebed that would emerge, or the lungs downwind.
The Salton Sea is what happens when we price the water we save but not the harm we move downstream. Fix the accounting, and the harm becomes something you can fund a solution to.
This is the same blind spot playing out across the West — a conservation or diversion win upstream that quietly imposes a loss somewhere with no standing to object. It's why the same math is now unfolding at the Great Salt Lake, and why the durable fix everywhere is the same: make the downstream dependency visible before you move the water.
what's already working
The response is not zero — and the people doing it deserve to be named. The Salton Sea Management Program (SSMP), created by California's AB 1095 in 2017, is building shallow managed wetlands and capping dust: roughly 4,100 acres of species-conservation habitat in its first phase, another 2,000 acres flooded for dust suppression in 2025, with a stated goal of 29,800 acres by 2028. Audubon California documents the birds and has recorded a 15 percent annual rise in shorebirds where habitat has been rebuilt. The Salton Sea Authority coordinates across Imperial and Riverside counties, the water districts, and the Torres-Martinez Desert Cahuilla Indians, whose ancestral homeland this basin is and roughly 11,000 acres of whose land the sea inundated. Alianza Coachella Valley carries the environmental-justice fight for the downwind towns.
The architecture exists. What's missing is the same thing missing everywhere in this basin: money that shows up at the scale and speed of the problem, instead of one grant cycle at a time. State funding is real but slow; the sea drops a foot a year while restoration is measured in agency budget years.
There is also a new payor in the room. The southern end of the sea sits on one of the largest lithium reserves in the world — an estimated 18 million metric tons, enough to meet a large share of U.S. demand — and "Lithium Valley" is moving from plan to construction. That industry will make billions from this basin. The open question is whether any of that value is structured to fund the restoration the community needs. This is where the accounting problem becomes an opportunity.
who's already paying — and who can't afford to look away
Start with who already carries responsibility. The Imperial Irrigation District and the state of California are on the hook by history and by law — IID's transfers reshaped the sea; California committed the SSMP. Both are spending, both are behind.
Now follow the dependency chain to the people who will pay one way or another. Lithium and geothermal developers — Controlled Thermal Resources, EnergySource, BHE Renewables — need a social license, clean air near their workforce, and a stable basin to operate in for decades. Public-health systems and Imperial County absorb the asthma costs today, in emergency visits and lost school days. Foundations already funding environmental justice in the region are writing checks into the same gap. Each of them is exposed to the shrinking sea. None of them, right now, has a shared instrument to act on it together.
That last sentence is the whole problem — and ensurance's clearest use.
the ensurance opportunity
ensurance is a way to fund the protection and restoration of a natural system upfront, and to let the people who depend on that system pay for it as an investment rather than a donation. It works by putting a price on outcomes that markets currently treat as free — the exact failure that is drying the Salton Sea. (Ensurance is not insurance: insurance pays you after the damage; ensurance funds the fix before the loss.)
Three moves fit this place.
Price the externality with spillover accounting. The core tool is tracing how one decision ripples outward — in this case, upstream water conservation to lost runoff to exposed playa to dust in a child's lungs. Once that chain is measured, the harm stops being invisible. It becomes a line item you can fund against. ensurance is built on the principle that there are no externalities — only costs someone hasn't been made to see yet.
Fund restoration through a certificate tied to a measured outcome. A certificate here is simply a claim tied to a specific, verifiable result — say, an acre of playa capped or managed wetland built, or a documented drop in PM10 near a named town. Buyers fund the work and hold proof of the outcome. Audubon's bird counts and the state's dust-monitoring network already generate the measurements; ensurance turns them into something fundable. That lets a lithium developer, a foundation, and the county pay into the same restoration acre and each hold a share of the result — the coordination layer none of them has today.
Structure extraction to fund restoration. The Salton Sea could be the first place where industrial value pulled out of a basin is routed to heal it. If even a small fraction of lithium revenue were committed to a place-based account — an agent, an onchain account for the sea that can hold funds and route them to verified restoration work — the math changes entirely. Billions in extraction, a slice priced back to the playa. That is not charity. It is a company paying for the clean air its own workforce breathes.
None of this replaces the SSMP, the Salton Sea Authority, Audubon, Alianza, or the tribe. It is infrastructure for the coalition that already exists — the funding mechanism they've been missing, matched to the pace of the loss.
what comes next
The sea drops about a foot every year this stays unpriced. "Lithium Valley" is being permitted right now — the rare, narrow window in which the terms that route extraction value to restoration are still being written. The question in front of California is not whether the Salton Sea can be helped; the SSMP already proves it can. The question is whether the cost of drying it gets carried by the people who breathe it, or shared by everyone the basin's water actually served.
That smell off the playa on Highway 111 is not weather. It is an unpaid bill, blowing into a schoolyard. It can be paid.
talk to someone who can help →
frequently asked questions
why is the Salton Sea drying up?
Because the water that sustained it was agricultural runoff, and there is now less of it. The sea was kept full by irrigation drainage from Imperial Valley farms. The 2003 Quantification Settlement Agreement conserved that water and transferred it to cities; "mitigation water" propping up the sea ended in 2017, and shrinkage tripled.
is the Salton Sea dust actually dangerous?
Yes. The exposed lakebed contains decades of pesticides, selenium, and other residue that become windblown PM10 dust. Imperial County childhood asthma rates exceed 20 percent — about double California's average — and a 2025 UC Irvine study linked dust exposure to declining lung function in local children.
is the Salton Sea being restored?
Partly. California's Salton Sea Management Program is building managed wetlands and dust-suppression projects, targeting 29,800 acres by 2028. Progress is real but slower than the roughly one-foot-per-year decline, which is the core funding gap.
how does this connect to the Colorado River crisis?
The Salton Sea is the terminal sink of Colorado River water used by Imperial Valley agriculture. Every conservation or transfer deal upstream changes how much runoff reaches the sea — making it a live example of the tradeoffs facing the whole basin after the 2026 rules expire.
who should pay to fix it?
The parties who depend on the basin and benefit from its water: the state and irrigation district already responsible, plus the lithium and geothermal developers extracting billions from the same ground, county health systems, and foundations. The barrier has been the lack of a shared instrument to fund restoration together — the gap ensurance is built to close.