A new ruling by a federal judge means the state’s Agribusiness Development Corporation (ADC) will no longer be able to use a century-old ditch system as an open sewer to dump millions of gallons of untreated, polluted water into the Pacific Ocean off West Kauai every day. Now, to stop violating the U.S. Clean Water Act, the agency must take actions to protect the people who use and enjoy the beaches and swim in the waters of West Kauai.

The judge ruled against ADC last week in a lawsuit Earthjustice brought on behalf of Na Kia‘i Kai, Surfrider Foundation and Pesticide Action Network. The ruling means that, to comply with the act, the state agency will have to get a permit for any pollution discharges from the Mana Plain ditch system near Kekaha, or otherwise stop polluting. The 40 miles of ditches collect polluted runoff and groundwater from thousands of acres of former plantation lands now being licensed to large-scale agribusinesses and industrial operations.

The system’s discharge waters pollute popular beaches like Barking Sands and MacArthur’s. These beaches are the lifeblood of the community, where people fish to feed their families, gather limu (seaweed) for food and ceremonial purposes, surf and swim. Children play in and around the drainage ditches where they meet the sea because the waters there are shallow and calm. But swimmers have regularly seen brown clouds in the ocean waters, and surfers have noted a distinctive chemical smell near the drainage ditches over the years.

The people who rely on these waters for subsistence and recreation should be able to trust that they are safe. A permit would provide these assurances by setting pollution limits that would require treatment of the water if it exceeds those limits, and requiring regular monitoring and reporting of water quality.

ADC had a permit until 2015, when it decided it no longer needed one based on a Clean Water Act exemption. But that exemption only applies in situations where pollutants aren’t added to the water — and that clearly isn’t the case here.

“It is undisputed that the water discharged contains various pesticides and agricultural chemicals, byproducts of agricultural chemicals, and heavy metals, as well as sediment from the unlined canals through which it passes,” U.S. District Court Judge Derrick K. Watson wrote in the ruling. “It is further undisputed that these pollutants include those from which the CWA seeks to protect waterways … ”

Congress passed the Clean Water Act and strengthened it over the years with one simple goal: to ensure that the nation’s waters are safe for fishing, swimming and recreation. By blatantly and continuously discharging polluted waters, ADC has ignored its legal responsibilities, exposing the residents of West Kauai to harmful pesticides, chemicals, heavy metals and other toxins.

To end these egregious Clean Water Act violations, ADC will have to either get a permit — like it had for many years — or end its illegal practice of discharging pollution. We hope ADC will do the right thing and expeditiously take steps to follow the law.

Kylie Wager Cruz is an attorney with Earthjustice’s MidPacific regional office in Honolulu.