A federal court ruled this month that the Environmental Protection Agency can't force Virginia to regulate stormwater flow because stormwater itself is not considered a pollutant.

The debate brought together Republican Virginia Attorney General Ken Cuccinelli and the Democratic-led Fairfax County Board of Supervisors in a lawsuit against the EPA filed early in 2012.

The debate stemmed from regulations the EPA established in April 2011 that limited the rate of stormwater allowed into Accotink Creek, a 25-mile tributary of the Potomac River. The intent was to limit the amount of sediment entering into the creek, since the EPA believed it had a negative effect on organisms in the river.

But Virginia officials argued that the EPA has overstepped its bounds by seeking to regulate stormwater levels and said that the Clean Water Act only gave the EPA permission to regulate pollutants themselves -- and stormwater is definitively not a pollutant.

U.S. District Court Judge Liam O'Grady sided with Virginia and Fairfax County in a ruling last week, and oral arguments were heard last month.

While EPA is charged with establishing limited on pollutants, "that does not give them authority to regulate nonpollutants," the judge wrote.

The ruling probably doesn't have far-reaching implications for other jurisdictions, at least for now. The EPA has only sought similar limitations in just a handful of other locations, all located in Missouri. But Cuccinelli did warn that if the state had been unsuccessful in its suit, it would have set a "dangerous precedent" for the EPA that would have caused costs for the state and its local governments to soar as it sought to implement the EPA's orders.

State officials have argued that it would have cost the county $250 million and the state $70 million to come into compliance with the rules set by the EPA, which would have required a nearly 50 percent reduction in peak stormwater flow into the creek.

Critics of the EPA had used the situation to deride the agency as taking such a hard line that it had essentially declared water itself as a pollutant. "EPA literally is treating water itself—the very substance the Clean Water Act was created to protect—as a pollutant," Cuccinelli wrote in his lawsuit.

That's somewhat of a mischaracterization of the EPA's position, which sought to use stormwater measurements as something of a proxy for sediment.

The EPA had argued that it's policy wasn't expressly prohibited by the Clean Water Act, so the agency was allowed to pursue it. Cuccinelli disagreed, and the judge took his side. "Logic like that would lead the EPA to conclude that if Congress didn't prohibit it from invading Mexico, it had the authority to invade Mexico," he said in a statement.

It's unclear why the EPA sought to use stormwater as a "surrogate" for sediment -- as opposed to limits directly on sediment itself. The EPA is likely to appeal the decision, according to an analysis by D.C law firm Barnes & Thornburg, which wrote a brief in support of Virginia. Governing is awaiting a response from the agency.