Environmental groups are urging California regulators to require stormwater permits for commercial properties like big-box stores and warehouses, arguing that runoff from large parking lots carries metals, chemicals, oil and bacteria into waterways that regula
Rain over a California shopping center looks harmless from above—until it hits the pavement.
Across large parking lots outside big-box stores and warehouses. water runs off carrying metal dust and chemicals from vehicle tires and brake pads. oil and grease from engines. and bacteria from trash. That mixture washes into storm drains, then into creeks, rivers, and beaches. Now. environmental advocates want state regulators to crack down by requiring stormwater permits—essentially best practices—for businesses they say have never been held accountable under a stormwater permit.
“Commercial properties right now are not regulated under any stormwater permit,” said Sean Bothwell, executive director of California Coastkeeper Alliance. “Think Costco, think Amazon warehouses. Large places with large parking lots are really what we’re going after.”
The push is aimed at state rulemaking that would extend beyond the cities and counties that currently bear responsibility for stormwater cleanup where the runoff lands. Nonprofit groups submitted petitions to regional water officials across the state this week demanding commercial properties be regulated—spurring a fight over who pays. who regulates. and what counts as “cleanup” in the first place.
The groups want the State Water Resources Control Board to establish a statewide rule, or permit, for “commercial, industrial and institutional” properties. That category would also include stadiums, malls, and private hospitals.
Bothwell warned of consequences if the state does not act. “our waterways will never be safe to fish or swim in, particularly Southern California beaches.”
He said his group estimates—using methods developed by the federal Environmental Protection Agency—that unregulated businesses are responsible for 30% to 60% of metals like copper and zinc found in waterways. depending on the area. At high concentrations, he said, those metals are toxic to fish and other animals.
In Southern California, many creeks and concrete-lined channels are already deemed “impaired” by regulators because pollution levels violate water quality standards.
The current enforcement approach, Bothwell said, leaves businesses without an obligation to reduce the runoff that ends up in drains. Instead, the cleanup costs fall on cities and counties. Researchers estimate California cities and counties spend more than $700 million each year on capturing and cleaning up stormwater.
California, the advocates say, would be the first in the country to adopt a statewide standard or permit for commercial properties. The state already requires stormwater permits for construction sites, roads, and certain industrial plants.
Business groups oppose the proposal.
John Myers. a spokesperson for the California Chamber of Commerce. said a mandate requiring stormwater permits for businesses has been discussed for several years in L.A. County after environmental groups won a favorable court ruling. He argued that copying that effort to other regions without a careful look at benefits and costs could harm the state economy.
The Los Angeles County Business Federation, or BizFed, raised similar concerns. “Everyone wants cleaner waterways. However, this proposal simply isn’t ready for prime time,” said Mike Lewis, BizFed’s water co-chair.
Lewis said in an email that. as written. the plan “hits existing property owners with retroactive costs while simultaneously ignoring the stormwater taxes they’ve been paying in good faith for years.” He added. “This seems less like environmental policy and more like a penalty. There are better, fairer ways to clean up stormwater.”.
Under the advocates’ concept. a statewide permit could push companies to either prevent contamination before it reaches the ground and drains or fund local projects that capture and treat runoff. If a statewide measure applied to commercial businesses. Lewis said many would likely need to build retention ponds or swales to filter contaminants before water percolates underground. Others, Bothwell said, could pay an annual fee.
Bothwell said money collected from companies would be used for building wetlands, water-absorbing parks, and other green spaces next to parking lots—features that help clean runoff instead of letting it run into storm drains.
That approach is coming as Southern California cities invest more in projects to capture stormwater and recharge groundwater, as the region seeks to rely less on water imported from Northern California and the Colorado River.
“If the state doesn’t act, contaminated water will continue running off businesses’ parking lots into drains,” Bruce Reznik, executive director of Los Angeles Waterkeeper, said—adding that it contributes to what he described as a “toxic soup” in Southern California waterways.
The petitions were submitted by California Coastkeeper Alliance and a coalition of local Waterkeeper groups to regional boards in the Inland Empire, San Diego, the Bay Area, the Central Coast, the North Coast, and the Sacramento Valley.
The groups invoked a provision of the Clean Water Act that authorizes states to require additional permits on a case-by-case basis. In L.A. County, they point to prior success: L.A. Waterkeeper and other environmental groups used the same provision to convince the EPA in 2024 to require permits for businesses near the polluted Dominguez Channel and Los Cerritos Channel. State regulators are preparing to issue those permits, Ailene Voisin, a spokesperson, said.
Voisin said the regional water boards received the new petitions and will consider them.
The effort also runs into political history. In 2022, Gov. Gavin Newsom vetoed legislation that would have required stormwater permits for many businesses statewide. In 2025, a similar bill faced opposition and died in the Legislature.
Now the fight is shifting toward whether state regulators will create an avenue for permits beyond that stalled legislative path—one that could determine whether polluted runoff from some of California’s largest properties becomes a business obligation rather than a city bill.
California stormwater permits polluted runoff big-box parking lots Clean Water Act State Water Resources Control Board California Coastkeeper Alliance Los Angeles Waterkeeper Gavin Newsom veto metals like copper and zinc stormwater taxes