A community group filed a lawsuit against Hawaii County on Monday saying treated wastewater from the county’s Kealakehe Wastewater Treatment Plant is polluting Honokohau Harbor in violation of the Clean Water Act.

Hui Malama Honokohau notified the county of its intent to sue in May, but the county didn’t act, prompting the complaint filed in U.S. District Court in Honolulu by attorneys from Earthjustice.

The county-owned wastewater treatment plant discharges about 1.7 million gallons of treated sewage every day into a natural disposal pit located in a lava field less than a mile from the water.

According to the suit, multiple scientific studies have found that the wastewater flows into the harbor and nearshore marine waters through the groundwater.

Hawaii County, the suit argues, must obtain a National Pollutant Discharge Elimination System permit in order to comply with the Clean Water Act, but so far the county has refused to do so.

Asked for a response to the lawsuit, spokesman Cyrus Johnasen said the county doesn’t comment on ongoing legal matters.

The complaint is strikingly similar to a high-profile case filed against Maui County for sewage water discharges from the injection wells at a West Maui wastewater treatment plant.

That case was brought in 2012 by the Hawai‘i Wildlife Fund, Sierra Club, Surfrider Foundation and West Maui Preservation Association. The county ended up appealing the case all the way to the U.S. Supreme Court.

In 2020, the high court ruled in favor of Earthjustice and its clients, affirming that point source discharges (like those from a wastewater treatment plant) into navigable waters (like the Pacific Ocean) through groundwater are regulated under the Clean Water Act.

The bottom line is that the federal Clean Water Act requires a National Pollutant Discharge Elimination System permit for any facility that discharges into waters as a tool for reducing water pollution.

In the Big Island case, the distance and travel time of wastewater — about 0.7 of a mile from the disposal pit to the harbor over a few months at most — are similar to the values the federal court in Hawaii had said triggered the Clean Water Act in the Maui County case.

According to the suit, polluted discharges from the Kealakehe plant, which started in 1993, have had a detrimental effect on the water quality and health of the nearshore waters and ecosystems in and nearby to the Honokohau Boat Harbor.

What’s more, the county has plans to increase the volume of wastewater treated at the facility, and discharges into the ocean will only increase in the future.

Hui Malama Honokohau describes itself as a group of Native Hawaiian cultural practitioners, fishers, paddlers, recreational ocean users and concerned community members who use Honokohau Harbor and nearby ocean waters.

“We have waited for far too long for the county to clean up its act,” said Mike Nakachi, president of Hui Malama Honokohau, in a news release. “No more. We cannot continue to sit idly by while the county dumps nearly two million gallons of contaminated wastewater into our oceans and along our reefs every day. We need to protect our community and the ocean on which we all depend.”

The suit says members of the hui fish and gather seaweed in the waters around Honokohau and have become increasingly concerned about contaminants in the water and in the fish, shellfish and seaweed they gather to feed their families.

“Since becoming aware of the significant pollution issues in Honokohau Harbor in 2017, Hui members have avoided fishing in the Honokohau Harbor area, but they would like to resume subsistence fishing in the harbor area and would do so regularly if the water quality improves,” the suit says.

According to the suit, the contaminants in the water are coming from the Keala­kehe plant, and the nutrient- laden groundwater entering the bay helps generate algal blooms that stress the bay’s reef ecosystems, making them more vulnerable to storms and other disturbances.

The discharged effluent is also the likely cause of numerous staph infections suffered by users of the harbor and surrounding waters, according to the suit.

The complaint seeks to compel the county to make upgrades to the operations of the Kealakehe plant to reduce the amount of contaminants entering the harbor. It also seeks civil penalties for the violations.

The group is encouraging the county to recycle the wastewater for irrigation, firefighting and other uses instead of dumping it into the harbor.