Almost hidden in Congress’ recent reauthorization of the federal flood insurance program is a provision that, if it stands, would have some homeowners in Wareham’s waterfront communities facing annual flood insurance costs climbing to $20,000 per year — or perhaps more.

To rein in the taxpayer cost of the flood insurance program, the Biggert-Waters Flood Insurance Reform Act, which takes effect October 1, dropped two key provisions that had kept rates where they are now: Flood insurance will no longer be subsidized by tax dollars for homes that pre-date the flood insurance program, and homes that met flood-zone requirements when they were built, but have since been placed in a higher risk flood zone, will no longer be “grandfathered” in to previous insurance rates.

To Congresspeople sitting in Washington, that simply meant that everyone will be paying for insurance based on the actual risk posed to each actual home. To homeowners in Swifts Beach, Onset, Cromesett, and more, it could mean a 2014 flood insurance bill that dwarfs other insurance and property tax costs combined.

Blame global warming or just a stretch of freaky, vicious weather, but the cost to the federal government of helping to insure coastal property has skyrocketed in recent years.

Because of the risk involved in flood insurance, it is only offered through the federal government program. As Katrina flattened New Orleans and Sandy swept into New York and New Jersey, insurance claims made it clear that flood insurance premiums were insufficient to cover the costs.

The Federal Emergency Management Agency estimates that homeowners will only see premiums higher than $20,000 "in rare cases," but local insurance agents say if the program is not revised, homeowners in the South Coast area will likely see premiums in excess of $20,000.

"I think it's absolutely devastating to the economy, and we need change," said David Dunn, who runs G.H. Dunn Insurance locations in West Wareham, Mattapoisett, and Buzzards Bay.

U.S. Rep. Bill Keating (D) said lawmakers must craft legislation that would properly fund the flood insurance program while helping homeowners.

“As someone who has heard from families in Southeastern Massachusetts seeing premium increases, I believe more work is needed to ensure the solvency and affordability of the flood insurance program,” said Keating. “Yet, I am disappointed to see that many homeowners will face sudden devastating hikes to flood insurance rates. While there is no question that a comprehensive long-term solution is needed, we need immediate action to help homeowners in Massachusetts and across the country.”

Keating co-sponsored the Flood Insurance Implementation Reform Act, which delays certain provisions of the Biggert-Waters legislation. The act would allow homeowners to avoid the impending rate increases, according to Keating’s spokeswoman Ganesan Annamalai.

Oddly enough, Maxine Waters -- co-author of the original legislation -- has also joined the Flood Insurance Implementation Reform Act as a co-sponsor.

Just how much rates will increase depends on the property.

Homeowners' whose primary home pre-dates the flood insurance program will keep their current subsidy until their property is sold or their policy lapses.

For owners of secondary homes that pre-date the program, annual flood insurance rates will increase by 25% until rates reach what FEMA deems is necessary for the property's risk of flooding.

When their flood insurance plans expire, homeowners will be required to get an elevation certificate from a surveyor, which, in essence, ensures the building is properly elevated.

Homeowners will have to foot the bill for the elevation certificate, which can cost $700 to $1,000, and bring it to an insurance company to receive a new rate.

While flood insurance is optional for those who own their homes outright, all mortgage-holders require that mortgaged properties most susceptible to flooding be insured, making the program particularly worrisome for homeowners on tight budgets.

Deb Martin of West Wareham-based Grassi Insurance says she has clients who are selling their homes because "the flood insurance has gotten too astronomical."

But the program, if not revised, will make it more difficult for homeowners to sell their homes.

Adding insult to injury, homebuyers currently have the option to "buy in" to the previous owner's subsidized flood insurance rate until the policy expires, but once that policy expires, the new rates go into effect. That option is no longer available as of October 1.

The legislation comes on the heels of the recent redrawing of the flood insurance maps, which put many homeowners in higher risk flood zone, and thus, made their homes more expensive to insure.

"I already see people not purchasing homes because of the cost of what flood insurance is going to be," said Martin.

Geoff Worrell of Wareham-based Prospect Mortgage urged both current homeowners and homebuyers to research the new flood insurance program and how it affects them, and work with a trusted professional to determine their best options.

Worrell recommended the National Flood Insurance Program's website, www.floodsmart.gov, which can be used to look up a property's flood risk and provides information about the program.