The head of the Metropolitan Washington Airports Authority warned that tolls approaching $5 could be on the horizon for drivers on the Dulles Toll Road.

Jack Potter, MWAA's president, said tolls could climb to cover the costs of construction on the Silver Line if local and federal funding sources do not come through.

This year tolls are up 50 cents from 2012 to $2.75, and next year they are scheduled to rise to $3.50.

"Every time, we have additional funding that will help mitigate the burden," Potter said during a D.C. Council oversight hearing Thursday afternoon.

The Virginia legislature has earmarked $300 million for Metro's Silver Line construction, but MWAA is still waiting on a federal loan to help cover construction costs.

Potter said that as the federal government has cut spending, it has placed a heavier burden on drivers on the toll road.

"It fell on the folks on the toll road. They're picking up a little more than 50 percent of the funding," Potter said during the oversight hearing run by Council Chairman Phil Mendelson.

The two-stage, multibillion-dollar Silver Line construction process is meant to connect Metro to Washington Dulles International Airport and Tysons Corner. When construction is completed, MWAA will fund the project through fares.

"I wasn't here when the decision was made, but I might have thought long and hard," Potter said of MWAA's decision to take control of the toll road, which has brought along with it political pressure to keep tolls low.

Potter was appointed to lead MWAA in June 2011 as the U.S. Department of Transportation's Inspector General's Office began an investigation that would ultimately identify a litany of problems with the agency. That report discovered that MWAA employees took trips paid for by contractors and hired family members.

Altogether, the audit revealed 12 problem areas. Potter told the chairman that improvements were already under way. MWAA's president estimated that about nine of the 12 recommendations would be complete by the end of June.

Potter said MWAA had hired an ethics officer and changed its policies to prevent future conflicts of interest. MWAA is also in the process of hiring two vice presidents, and another one is set to begin work on Monday, according to Potter's testimony.

He said MWAA would post online, four times a year, its contracts worth more than $50,000.

"Very quickly," Potter said, "the culture of the organization is changing."

Mendelson and Councilman David Grosso said they had seen positive signs that MWAA was making necessary reforms.

"I am hopeful that this progress does get out in the public consciousness," Mendelson said.