When District officials scrambled to put in place health insurance exchanges mandated by President Obama's Patient Protection and Affordable Care Act, they faced a number of potential pitfalls -- including the possibility that monthly costs would skyrocket.

As insurers have begun unveiling their plans, the huge cost increases that some prognosticators had foreseen have not come to pass.

"The bottom line here in the District is we're not seeing the rate shock that some other folks around the nation have been discussing," said Mila Kofman, executive director of the DC Health Benefit Exchange Authority.

There had also been concern that CareFirst, which provides health insurance to the majority of District residents on individual and small-business exchanges, would not fully participate in the health exchange. But the city has announced that the health provider will offer bronze, silver, gold and platinum plans for the both the city's individual and small-business health benefit exchange.

"We're obviously very happy to see the companies have submitted almost 300 plans," said William White, commissioner of the Department of Insurance, Securities and Banking. "In short, we're well on our way to a whole new market place that's transparent and competitive."

CareFirst PPO health insurance for an average 40-year-old on a gold-rated plan in the District's health benefit exchange for small businesses is expected to cost about $390 a month. On the individual marketplace, a plan for the same average 40-year-old will cost about $367.

The actual price paid by consumers would be subsidies for many families.

"I'm pleased that all of them are going to do business through the exchange," Yvette Alexander, chairwoman of the D.C. Council's Committee on Health, said about the District's current health insurance providers.

Now, the District and federal government will kick the tires on those plans to make sure that the costs are fair -- and companies could still adjust their prices to keep up with their competitors.

"This is the first time that insurers have seen what their competitors are offering," said Leighton Ku, a professor at George Washington University and a member of the health exchange's executive board. "That's the purpose of having an open and transparent market."

The exchange is scheduled to open on Oct. 1.