The Coachella Valley stretches roughly 45 miles through the desert of Riverside County in southeastern California. It’s home to about 450,000 people — from the wealth of Palm Springs and Indian Wells to the farmworker communities of Thermal, Mecca, and Oasis. And beneath this valley, the groundwater that supplies nearly all of the region’s drinking water contains contaminants that have made the Coachella Valley one of California’s most significant water quality battlegrounds.
Chromium-6: The Erin Brockovich Chemical
Hexavalent chromium (chromium-6) is the contaminant most closely associated with the Coachella Valley’s water quality challenges. This is the same chemical compound made famous by the Erin Brockovich case in Hinkley, California — and it occurs naturally in the Coachella Valley’s volcanic and metamorphic geology at levels that exceed California’s public health goal.
California established a maximum contaminant level (MCL) of 10 micrograms per liter (µg/L) for total chromium in drinking water, and the state’s public health goal for chromium-6 specifically is 0.02 µg/L — a level far below what many Coachella Valley wells produce. Several water systems in the valley have detected chromium-6 at levels that, while meeting the total chromium MCL, significantly exceed the state’s public health goal.
The challenge with chromium-6 is that it occurs naturally in the aquifer materials. This isn’t industrial contamination from a single polluter — it’s baked into the geology. That means there’s no responsible party to force a cleanup, and water systems have to either treat the water, blend it with cleaner sources, or find alternative supplies. All of those options are expensive, and the communities most affected — the small, low-income systems in the eastern valley — are the least equipped to pay for them.
Nitrate From Agriculture
The Coachella Valley’s eastern end is intensively farmed. Date palms, citrus, table grapes, peppers, and other crops are irrigated with Colorado River water delivered through the Coachella Canal. Decades of fertilizer application have pushed nitrates into the shallow groundwater, and some wells in the agricultural areas produce water that approaches or exceeds the EPA’s 10 mg/L MCL for nitrate.
Nitrate contamination is particularly concerning because of who it affects. The communities of Thermal, Oasis, Mecca, and North Shore — predominantly Latino, predominantly low-income — sit directly above the most contaminated portions of the aquifer. Many residents in these areas are served by small water systems or private wells that lack the treatment infrastructure to remove nitrates.
The California State Water Resources Control Board has identified several small water systems in eastern Coachella Valley as failing to meet drinking water standards. Some have been placed under compliance orders, and the state has directed funding toward consolidation projects that would connect small, failing systems to larger, better-equipped water providers.
Perchlorate: A Military Legacy
Perchlorate — a chemical used in rocket propellant, munitions, and fireworks — has been detected in Coachella Valley groundwater. The likely sources include historical military operations at sites in the broader region, as well as potential agricultural sources (some imported fertilizers have contained perchlorate as a contaminant).
California has established an MCL of 6 µg/L for perchlorate in drinking water. Some Coachella Valley wells have shown detectable levels, though most are below the MCL [NEEDS VERIFICATION]. Perchlorate interferes with thyroid function, making it particularly concerning for pregnant women and developing children.
The Salton Sea Connection
The Salton Sea — the massive, shrinking lake at the valley’s southern end — isn’t a direct drinking water source, but its decline affects regional air and water quality in ways that compound the Coachella Valley’s challenges.
As the Salton Sea recedes, exposed lakebed (playa) generates dust storms that carry fine particulate matter, including selenium, arsenic, and other contaminants from decades of agricultural drainage that fed the sea. This dust can settle on land surfaces and eventually work its way into surface water and shallow groundwater through runoff and infiltration.
The Salton Sea’s decline also reflects the broader water dynamics of the region: as Colorado River water gets redirected from agricultural use to urban use (particularly through fallowing agreements that send water to San Diego and other coastal cities), the agricultural drainage that sustains the Salton Sea diminishes. This is an environmental justice issue with direct water quality implications for the valley’s most vulnerable communities.
Environmental Justice and Water Access
The Coachella Valley is one of California’s starkest illustrations of water inequality. Within a 30-mile drive, you can go from multi-million-dollar homes with lush golf course landscapes to communities where residents receive water that doesn’t meet basic safety standards.
California’s Human Right to Water Act (AB 685, signed in 2012) declared that every Californian has the right to safe, clean, affordable, and accessible drinking water. In the eastern Coachella Valley, that right remains unrealized for thousands of residents. The state’s SAFER (Safe and Affordable Funding for Equity and Resilience) program, established in 2019, directs funding toward communities that lack safe drinking water — and eastern Coachella Valley communities have been among the program’s priorities.
What Coachella Valley Residents Can Do
Know your water system. The Coachella Valley has dozens of water providers ranging from large utilities like Coachella Valley Water District and Desert Water Agency to tiny mutual water companies. Your water quality depends heavily on which system serves you. Request the annual Consumer Confidence Report from your provider.
Test private wells. If you’re on a private well — common in the eastern valley — test for chromium-6, nitrate, bacteria, and TDS at minimum. The Riverside County Department of Environmental Health can provide guidance on testing.
Consider treatment. For chromium-6, reverse osmosis and strong-base anion exchange are effective treatment technologies. For nitrate, reverse osmosis and ion exchange systems can reduce levels below the MCL. Point-of-use RO systems are the most practical option for most households.
Get involved in water system consolidation. If you’re served by a small system with compliance issues, support efforts to consolidate with a larger provider that has the resources to treat and monitor water effectively.
If you’re concerned about your water quality, a certified water treatment professional can test your water and advise on solutions.