Federal and city regulators may have to create entirely new regulations for E. coli levels in D.C.’s waterways after a U.S. District Court on Monday night determined that the current standards violate the Clean Water Act, as well as the District’s own water quality laws.

The judge vacated D.C.’s old regulations on the basis that the Environmental Protection Agency failed to approve them in accordance with federal and local laws. The new standards must be set up within the year, and they must be stringent enough to allow for safe kayaking, canoeing, and fishing in D.C.’s rivers and tributaries, according to Seth Johnson, a lawyer for Earth Justice, which represented the plaintiffs in the case.

The lawsuit against the EPA was filed in 2016 on behalf of three environmental groups: Anacostia Riverkeeper, the Kingman Park Civic Association, and the Potomac Riverkeeper Network. As the case got underway, DC Water interceded as a defendant, arguing on the EPA’s side.

The standards at issue in the suit are called “total maximum daily loads,” or TMDLs. The idea behind a TMDL is mostly what it sounds like: it sets a maximum amount of a pollutant allowed to enter a body of water per day  per the EPA. States and the District of Columbia are required to set a TMDL for pollutants in bodies of water that are “impaired” (aka that have pollutants in them) and the EPA approves those TMDLs in accordance with the federal Clean Water Act.

The crux of the plaintiffs’ argument was that the EPA approved inappropriate TMDLs for E. coli that had been set by the District government. E. coli is a bacteria often found in fecal matter that can cause severe illness, including vomiting, diarrhea, fever, pink eye, and skin infections and rashes.

The court ruled that the TMDLs set by the city were illegal for two reasons: first, because they were not true maximums, since the EPA said that it was acceptable for the waterways to exceed the numeric TMDL in a 24-hour period. Second, the court found that the EPA approved the TMDL without actually establishing that the level would make the waterways safer and allow people, plants, and animals to use the water without getting sick, as D.C.’s municipal regulations require.

“In this case, we were suing the EPA and basically saying, hey, these total maximum daily loads are not total and they’re not maximum, and as a result they’re not as protective as they need to be. You didn’t show how they’re going to make the water safe,” Johnson says. The court largely agreed, ruling against the plaintiffs only on one technical part of their argument that had to do with a specific form of measuring pollutants in the water.

As a result—and barring an appeal to the decision—the TMDLs will have to be rewritten in such a way that the rivers and their tributaries will meet D.C.’s own water quality standards.

The EPA is “reviewing the decision,” a spokesperson tells DCist. DC Water is also reviewing the ruling, CEO David Gadis tells DCist via email. The agency operates the Blue Plains Wastewater Treatment Plant, as well as the sewer system, and runoff from those pipes often ends up in the District’s waterways. In recent years, DC Water has undertaken a bevy of projects to reduce pollution, including a new sewer tunnel that captured 5 billion gallons of sewage in its first year of use.

“Our efforts thus far have resulted in significant improvements in the Anacostia River’s water quality, and we will continue our active engagement to bring tangible, measurable benefits to the District’s waterways,” Gadis says.

But activists say the new standards will also help improve water quality in the District’s waterways.

“D.C.’s water quality standards give all of us the right to use these waters without getting sick. This is an important step toward realizing that goal,” Johnson says. “These TMDLs are an important tool for cleaning up dirty water, and it’s important that they be meaningful and that they protect all of the water quality standards, primarily that the water be clean and usable.”