A federal judge has ruled that a state agency — the Hawaii Agribusiness Development Corp. — violated the federal Clean Water Act off of Kauai’s west side by discharging millions of gallons of water contaminated with pesticides, sediment and heavy metals along Barking Sands and MacArthur beaches without a permit.

U.S. District Judge Derrick Watson’s ruling Tuesday means that the Agribusiness Development Corp. needs to obtain a National Pollutant Discharge Elimination System permit — or stop discharging materials through a plantation-era ditch system it operates on the Manana Plain for current tenants, which include agribusinesses and industrial operations.

“They are not exempt from the Clean Water Act,” Earthjustice attorney Kylie Wager Cruz told the Honolulu Star-Advertiser. “In order to comply with the Clean Water Act, they need to obtain a permit — or stop discharging altogether. Until they do either of those two things, they’re violating the Clean Water Act every day.”

In a statement to the Star-Advertiser, the Agribusiness Development Corp. said, “ADC is currently reviewing the recent court order to determine the best course of action regarding this matter. ADC and its tenants will continue to implement best management practices to care for the land and water, to monitor discharges, and to find better ways to improve the drainage system for the residential, commercial and farming community in Kekaha.”

The agency was created by the Legislature in 1994 and is administratively attached to the state Department of Agriculture, according to its website.

“ADC’s role is to protect the future of agriculture in Hawaii by facilitating its transformation from a dual crop economy of sugar and pineapple to a multicrop industry,” according to the website. “The breadth of ADC’s responsibilities includes transitioning former plantation lands and water systems to diversified long-term agricultural use, initiating and developing diversified agriculture facilities, and finding innovative solutions for issues facing the agricultural industry today.”

Watson ruled that the agency has been discharging polluted water without a National Pollutant Discharge Elimination System permit since it withdrew its renewal application in August 2015.

If the ADC applies for a permit, it likely would be monitored by the state Health Department, Cruz said.

“DOH can go above and beyond EPA (the federal Environmental Protection Agency) on stricter limits,” Cruz said. “The outfalls are discharging at popular recreation, surfing and gathering areas. DOH should be ensuring the limits are strict enough so all those people are protected.”

Cruz said Watson’s ruling vindicates community groups Na Kia‘i Kai, Surf­rider Foundation and the Pesticide Action Network.

Earthjustice in a news release quoted members of each organization, including Surfrider Foundation member Gordon LaBedz, who said, “The ditches empty directly into the Kinikini surf break. Test after test shows the ditches contain pollutants that are harmful to people and our precious ocean ecosystem. We hope the Agribusiness Development Corporation will take the court’s order seriously and immediately begin the process of bringing the ditches into compliance with the Clean Water Act.”

The roughly 40 miles of drainage ditches collect polluted runoff and ground­water from thousands of acres of former sugar plantation lands that the Agribusiness Development Corp. “now licenses to large-scale agribusinesses and various industrial operations,” according to Earthjustice.

The ditches are unlined, eroding and discharging contaminated water along beaches “where people fish to feed their families, gather limu for subsistence and ceremonial purposes, surf, and swim,” Earthjustice said. “Children regularly play in and around the drainage ditch outfalls. Surfers have noted a distinctive chemical smell near the drainage ditches over the years.”