Thanks to the cooperation between the District and the counties of Fairfax, Montgomery and Prince George’s, the Blue Plains sewage treatment facility is top-notch at cleaning wastewater so that it is fit to pump back into the Potomac River. (Linda Davidson/The Washington Post)

Regular readers know I complain frequently about the lack of cooperation within the Washington region. So it’s only fair for me to take note and celebrate when the area manages the rare feat of working together successfully on something big.

That something is sewage.

It hardly draws much attention, but our area is a world-beater at cleaning wastewater so it’s fit to pump back into the Potomac.

The Blue Plains plant in the District — north of the Wilson Bridge and across the river from Alexandria — is the largest “advanced” sewage treatment facility on the planet. “Advanced” means it uses extra steps to produce cleaner water than inferior plants in more backward regions.

Blue Plains shows that the District and various suburbs can set aside their differences when the mutual advantage is clear. All benefit from lower costs, and a cleaner river and Chesapeake Bay.

A District agency, DC Water, operates the facility, but most of its 2 million customers are in the suburbs. The District and our three largest suburban counties — Fairfax, Montgomery and Prince George’s — have shared the plant’s expenses since 1985 with little infighting.

Now they’ve signed a new, 99-year accord to continue doing so, a feat saluted Wednesday at a high-level event at the Metropolitan Washington Council of Governments.

“I would describe what we’re doing today as regionalism at its best,” Fairfax County Board of Supervisors Chairman Sharon Bulova (D) said.

“We sometimes compete with each other. We sometimes disagree with each other over different things. But we are one big family in the Washington metropolitan area, and it’s important that we come together and work well together on the things that matter, such as that we have clean water,” she said.

District Mayor Vince Gray (D), Montgomery County Executive Ike Leggett (D) and Prince George’s Chief Administrative Officer Brad Seamon also attended.

It took a decade to thrash out the new Intermunicipal Agreement. The suburbs agreed to pick up more of the costs than before, when new analyses showed they were responsible for a larger share of the water being treated.

Still, the collaboration means lower water bills for everybody served by Blue Plains. That’s because the plant’s large size translates into greater efficiency. DC Water says it collects and treats a million gallons of wastewater for $1,330, compared with the national average of $2,308.

A series of technical improvements at the plant have also yielded a significantly cleaner river downstream since 1965, when President Lyndon Johnson pronounced the Potomac a “national disgrace.” Underwater grasses have returned and water clarity has improved.

“Typically, our discharge into the Potomac is cleaner than the water already in the river,” DC Water General Manager George Hawkins said.

Upgrades at Blue Plains are expected to reduce nitrogen pollution flowing into the Chesapeake by between 2 million and 3 million pounds a year, said Beth McGee, senior water quality scientist at the Chesapeake Bay Foundation.

That’s a respectable gain — albeit only a fraction of the overall federal goal by 2025 of reducing the nitrogen load in the bay by 60 million to 70 million pounds.

Given this success, I’d like to see the Blue Plains spirit extended to some other common challenges facing the Washington area.

For instance, let’s accept that the region would be best served by placing the new FBI headquarters at one of the underused Metro stations in Prince George’s. As I’ve written before, that would help reduce traffic and redress the imbalance in jobs in the area.

It would annoy Northern Virginians, who want the FBI for themselves. We can placate them by promising to add a Potomac crossing north of the District.

Finally, the area should get behind a project to build a new stadium for the Redskins — in the District. We can handle 370 million gallons of sewage a day. We ought to be able to put a football team back in the city for which it’s named.

For previous Robert McCartney columns, go to washingtonpost.