COLUMBUS, Ohio— The Ohio Environmental Council, Center for Biological Diversity and Darby Creek Association appealed a Plain City Wastewater Treatment Plant permit Wednesday that would double the amount of polluting discharge the facility is allowed to release into Big Darby Creek.

Big Darby Creek is a National Scenic River and one of the most biologically diverse rivers in the Midwest. The increase in polluting wastewater will jeopardize five endangered mussel species, fish and people. The rare and beautiful freshwater mussels are as colorful and unique as their names: rabbitsfoot, rayed bean, northern riffleshell, clubshell and snuffbox.

“The endangered mussels in Big Darby Creek are dying and headed toward extinction,” said Will Harlan, a scientist at the Center. “Mussels are nature’s wastewater treatment plants, filtering out pollutants and cleaning our rivers for free. They once lined the banks of Big Darby Creek for miles, but now only a few small populations remain.”

Fish are similarly threatened by water pollution. A catfish found only in the Big Darby Creek watershed was recently declared extinct. The toxic discharges also harm people. Wastewater from Plain City’s treatment plant includes heavy metals like mercury, arsenic, cadmium and lead. Microplastics, pesticides, hormones and pharmaceuticals are also part of the effluent that will double under the new permit.

The conservation groups are urging the Ohio Environmental Protection Agency to initiate regional planning to ensure the long-term health of Big Darby Creek.

“We are disappointed that we must resort to a legal appeal when in the past, cooperation and collaboration have driven the effort to protect Big Darby,” said John Tetzloff, president of the Darby Creek Association. “In Franklin County, the Ohio Environmental Protection Agency placed a pause on new development until conservation planning was in place. All we ask is that similar care be shown in the rest of the watershed.”

The state agency approved the increase despite hundreds of public comments calling for a halt to new wastewater permitting affecting the river until comprehensive environmental review and planning is completed. The permit was issued on Oct. 3, and doubles the amount of effluent Plain City can discharge directly into Big Darby Creek — from 0.75 to 1.5 million gallons per day. The Ohio Environmental Protection Agency failed to consider the impacts to endangered mussels in issuing this permit.

“As the Clean Water Act is celebrated for its 50th anniversary, now is the time to ensure strong safeguards are in place for one of the most biologically rich streams in the entire Midwest,” said Nathan Johnson, public lands director for the Ohio Environmental Council. “The Big Darby is a natural jewel for Central Ohioans, and countless school children and families play, learn and recreate in the Big Darby every year. If we don’t protect the Darby’s rare and declining biodiversity now, we will lose it forever.”

The Eastern United States is a global hotspot of freshwater mussel biodiversity. Unfortunately, freshwater mussels are the country's most imperiled group of animals. More than 70% of North America's mussel species are endangered or already extinct.