But it's unclear if the agency will pay a penny.
"At this time we have not determined whether it will be appropriate to remit payment for those assessments," spokeswoman Dorothy J. Clark said. "We will study the issue and come to a decision in the near future."
The uncertainty reflects a broader murkiness on whether federal agencies will pay the new state-mandated fee. Derided by some as a "rain tax," the fees are meant to pay for pollution-reducing improvements and are generally based on a property's amount of paved or hard surfaces.
Anne Arundel County Executive Laura Neuman said Friday that the question of federal payments is "a moving target," adding, "We're trying to seek clarification on the issue."
The county is home to two large federal properties: the Naval Academy and Fort Meade, which houses the National Security Agency. Officials at Fort Meade and the Navy office that oversees the academy's facilities did not respond to questions about stormwater fees.
A 2011 federal law sponsored by U.S. Sen. Ben Cardin would seem to have settled the matter. It says that the federal government must pay all "reasonable" stormwater fees, and he has said the measure "holds polluters financially accountable for the pollution that they cause, including Uncle Sam."
And while the state General Assembly exempted local and state government when it approved the stormwater fee law last year, it did not give the federal government a pass.
Yet it's not so simple, says Maryland Association of Counties lobbyist Les Knapp. "There is a policy at the federal level to honor local stormwater fees, but there is an out — federal agencies do not have to pay the fee if the state government exempts itself from paying the fee," he said.
Sure enough, he said: "Federal agencies have maintained that they do not have to pay the fee." Officials in Montgomery County, which has had a stormwater fee for several years, say federal agencies haven't yet paid any fees there.
Last week a spokeswoman for the General Services Administration, which acts as landlord for many federal properties, said the agency "expects to pay such assessments … once we have determined that they meet the requirements" of the Cardin law.
Del. Maggie McIntosh, a Baltimore Democrat, said she expects the O'Malley administration to include funds in next year's state budget to cover stormwater fee payments to the counties for any state properties not already required to control their runoff.
She acknowledged some federal agencies are apparently refusing to pay as long as the state doesn't. "If we can get the state to pay, that will help us when we go to collect from the feds," she said.
Like Baltimore County, Baltimore City and Howard County plan to charge fees on federal properties.
Harford County officials say they will bill most federal sites, including an Army tank testing facility and Postal Service land. But county spokesman Ben Lloyd said the county doesn't think it can collect from Aberdeen Proving Ground because it has its own federal stormwater discharge permit.
Noting that the new fees stem from federal mandates, Lloyd said it would be "ironic" for the U.S. government to assert a blanket exemption, "especially given the strain that these requirements place on our taxpaying citizens and businesses trying to stay afloat in this economy."
Sun reporter Timothy B. Wheeler contributed to this article.