The federal government proposed raising the required amount of oxygen in an urban section of the Delaware River to improve conditions for fish and help meet a legal goal for a “fishable and swimmable” river.

The U.S. Environmental Protection Agency said Thursday it wants to raise the oxygen level — in a measure called “dissolved oxygen” — to between 5.4 and 7 milligrams per liter from the current requirement of 3.5, a standard that has stood since 1967.

The higher oxygen standard in a 38-mile tidal section of the river between Camden and Wilmington, DE would make it easier for fish to breed, particularly the endangered Atlantic sturgeon, whose Delaware River population is believed to be on the brink of extinction.

Declining oxygen levels in water hurt the growth and survival of fish and other aquatic organisms, the EPA said. “Maintaining a healthy ecosystem requires dissolved oxygen levels above thresholds that impair growth and survival of aquatic species,” the agency said.

The change would also bring that part of the river into line with its other sections, where oxygen levels are higher, and which are already classified as “fishable and swimmable,” as required under the federal Clean Water Act of 1972.

Changes in wastewater treatment

Boosting the river’s oxygen content would require wastewater treatment plants to reduce the ammonia they discharge into the river, which then depletes oxygen. The plants would need to install “nitrification” technology at a combined cost of $137 million a year for 30 years, the EPA said.

That technology is proven to work, and has been widely adopted in other places, said Greg Voigt, an environmental scientist with the EPA, during a call with reporters.

“This is stuff that other municipalities have implemented across these jurisdictions, and have used to successfully comply with regulatory requirements,” Voigt said.

The permit limits that would enable the new oxygen standard to be met will be the same as those already required for treatment plants in municipalities outside the river’s urban stretch, he said. “We’re not looking to raise the bar for these dischargers far and above what everybody else has to comply with. We’re basically just bringing everybody up to the same level playing field,” he said.

A spokesman for the Camden County Municipal Utilities Authority, which could be affected by the new rule, said it is evaluating the plan. “We want to be able to digest the full impact of this new policy on the authority and not speculate on what it could mean to the operation,” said Dan Keashen.

How the EPA took control

The EPA’s action is contained in a proposed rule under the Clean Water Act that is now subject to a 60-day public comment period, and which is expected to be finalized by the end of 2024, Voigt said.

Although the estuary has been used for limited fish propagation for the last 20 years, some fish likely face “lethal or sub-lethal” effects because of the current dissolved-oxygen standard, the EPA said in December 2022.

‘Unfortunately, while the EPA took an important step forward, they did not set the numbers as high as the science dictates and the sturgeon of the Delaware River need.’ —  Maya van Rossum, Delaware Riverkeeper Network

The plan follows a surprise announcement by the EPA a year ago that it had determined that water quality in the urban Delaware did not meet the requirements of the federal law, and so the agency was taking over updating the dissolved-oxygen standard from the local interstate regulator, the Delaware River Basin Commission.

The commission was conducting its own investigation into whether to raise the oxygen standard, and in September last year concluded that it would be possible to raise dissolved oxygen and upgrade the river’s designated use.

It had long been accused by environmental groups of dragging its feet on the issue. The delay led five of them to petition the EPA to take charge of the review, leading to the federal agency’s unexpected agreement with their request in December 2022.

Not good enough?

On Thursday, the groups welcomed the EPA’s latest plan but said it does not go far enough.

The proposal sets “meaningfully higher oxygen standards” in the estuary but stops short of a level that would protect the Atlantic sturgeon and the shortnose sturgeon, the groups said in a statement.

“Unfortunately, while the EPA took an important step forward, they did not set the numbers as high as the science dictates and the sturgeon of the Delaware River need,” said Maya van Rossum, leader of Delaware Riverkeeper Network, which led the petition.

Van Rossum urged the EPA to raise the proposed dissolved oxygen standard higher to a range of 6.3 to 7 mg/L to protect the sturgeon. She predicted that the operators of wastewater treatment plants will fight the changes because of their extra costs.

Credit: (Mauro Orlando from Flickr; CC BY-NC-ND 2.0)

Doug O’Malley, director of Environment New Jersey, called the EPA’s plan “a huge step” but said there’s more work to be done. “The Delaware River is facing unprecedented and growing pollution challenges, which led to the necessary but rare move by EPA to intervene and work to set standards that are more protective than the status quo,” he said.

The Delaware River Basin Commission, which was forced to take a back seat in the dissolved-oxygen review when the EPA stepped in, called the move a “milestone” in the decades-long effort to create a cleaner river. It said it would continue to work with the EPA and the environmental agencies of member states New Jersey, New York, Pennsylvania and Delaware to plan for implementation of the new standard.

“As waterbodies around the country struggle to achieve and maintain measurable water-quality improvements that balance ecological needs with economic growth and water affordability, the Delaware River estuary is a model for federal and interstate collaboration on shared clean-water goals,” said the commission’s executive director, Steve Tambini.

The plans represent an additional layer of environmental protection for the Delaware River after years when it has been neglected in comparison with the Chesapeake Bay, said Adam Ortiz, the EPA’s regional administrator for the mid-Atlantic.

“We spend a lot of time working on the Chesapeake Bay, and that’s important,” he said. “But there are other critical waterways where people are just as entitled to high-quality natural assets. The Delaware River in some ways has been lagging in those protections. The announcement today is a step toward healing that breach.”