Many State Flood Maps Are Not Up to Date. Connecticut Is Trying to Fix That

Connecticut is taking an unusual step to confront a growing national problem: flood maps that lag reality. The state has launched a public climate-risk mapping tool where residents can see the estimated flood exposure of their property — along with wildfire, wind and other climate risks. The tool, which is accessible through the insurance department’s website, is powered by the same type of private risk-modeling firm that insurers turn to for setting rates.

Severe flooding in western Connecticut in 2024, in which three people died and thousands of properties were destroyed or damaged, underscored for state officials just how wide the gap can be between mapped risk and lived experience.

Interim Insurance Commissioner Josh Hershman emphasizes that the portal is informational only; it does not change insurance requirements or zoning rules. The goal, he said, is to close information gaps before the next disaster strikes.

“If you don’t see water, you might not think you have a flood risk,” he said. “This is about giving consumers as many tools as possible so they can make an educated decision.”

The initiative has ignited a familiar debate over the unintended consequences of risk disclosure. A lot of wealth is tied up in home values, and homeowners and some in the real estate industry complain that the models aren’t transparent or regulated; they worry about devaluation.

Alexander Chingas, an agent with the Bross Chingas Bross Team at Coldwell Banker Realty in Westport, said that the models have led buyers to rule out homes that are perfectly good. “The problem is some people don’t look at the tools as a starting point but rather view them as final and absolute,” Chingas said.

Connecticut’s experiment comes against a backdrop of rising climate-fueled extreme weather catastrophes and rising home insurance costs.

Insurers use advanced risk models to determine premiums, but this has become increasingly controversial —particularly in California — as those models, which are private and not required to be responsive to homeowner feedback, have predicted levels of risk that sometimes send insurance premiums soaring.

Flood insurance is a little different since it is excluded in most home policies. Only people seeking federally backed mortgages for homes in a zone that the Federal Emergency Management Agency designates as a severe risk are required to get flood insurance. On its website, FEMA says that on average, 40% of the flood insurance claims it gets for the National Flood Insurance Program are outside of these zones. And the actual number of people experiencing flooding is likely greater than that, because that figure doesn’t represent those without flood insurance.

Connecticut decided to partner with hazard risk modeler First Street Technologies Inc. — which rates risk on a scale of one to 10 — in large part to have people re-examine whether they need flood insurance. Before launching the portal, the department asked First Street to compare its projections with the August 2024 flood footprint. The state found the modeled maps closely aligned with properties that experienced flooding.

First Street said their model identifies approximately 81,000 more properties (all types, not just residential structures) facing severe flood risk than FEMA does. That difference, they said, is largely because FEMA maps do not include localized flooding from heavy rainfall.

There is debate about which of the many private risk models is more accurate. A recent paper published in the Journal of Catastrophe Risk and Resilience analyzed the performance of seven of the most widely used private risk models against actual NFIP claims data and found that while three—Verisk, KatRisk and Moody’s R.M.S.—represent historical flood losses within a 4 % differential of actual NFIP claims, First Street reports flood damage estimates “nearly twice as high.”

First Street chief executive officer Matthew Eby said that paper used data from a 2020 version of a First Street model, which has since been updated. He added: “First Street’s model should not be compared against traditional catastrophe models that are calibrated against historical data. The climate is not stationary, and flooding and damages are already increasing—any traditional, rearward-facing catastrophe model is expected to underestimate current risk.”

There is no doubt that a warming climate is adding more moisture to the air and making rainfall events more severe. As insured damages from natural catastrophes in the US now routinely exceed $100 billion, there have been spotty efforts by states to better inform residents of changing risks. Florida has maps for flooding and storm surge. California and Washington both map wildfire risk zones for the public. Local versions of FEMA flood maps are widely available. Commercial real estate sites like Redfin already display some risk data from First Street.

But Connecticut says it is the first to provide a “pro” version of the First Street model not usually available to the public. Instead of a general risk score, users can see street-level details and specific projected financial losses from flooding — information typically reserved for insurers and investors.

The portal coincides with new state legal requirements. Beginning July 1, 2026, Public Act 25-33 will require sellers and landlords to disclose flood risk details to buyers and tenants, including FEMA zones, flood history, and elevation certificates — bringing a property’s risk history to the closing table.

It’s also too early to gauge effects on flood insurance purchases or home prices.

Jonathan Miller, president of appraisal firm Miller Samuel Inc., who lives in Connecticut, said the effect of flood-risk disclosures depends on broader market conditions.

“In periods where the market is tight, it has less impact,” Miller said. “When the market is soft, it arguably has more impact on values. The market is very tight in Connecticut.”

Some homeowners wonder if the portal is already causing them trouble. Laura Lageman’s 1835 farmhouse in Woodbury, a strong market, has been for sale for months. She worries that the 9-out-of-10 flood designation given to her home — despite its location outside FEMA’s high-risk zones — may be discouraging potential buyers.

“We accepted an offer, but for no reason, they backed out,” she said. “It’s been strange.”

Compass agent Mark Pruner in Greenwich said the numerical risk ratings have the potential to distract buyers.

“It adds confusion and an unreal level of specificity,” Pruner said. “The difference between a six and an eight for a homeowner who lives there 10 years probably is not significant.”

Pushback against First Street scores caused the real estate site Zillow to stop displaying them last year. This came after a couple in Chappaqua, New York, just miles from the Connecticut border, sued both First Street and Zillow for listing their home as a 9-out-of-10 severe flood risk even though it was not in the FEMA severe flood zone. They argue that it damaged their property’s value and are asking for half a million dollars in compensation.

Both First Street and Zillow Group Inc. said they could not comment on ongoing litigation; but they have asked the court for the complaint to be dismissed, and parties are awaiting a ruling by the judge.

“There’s always tension when information changes how people perceive risk,” said Gary Yohe, a professor of economics and environmental studies, emeritus at Wesleyan University. Yet he said this is an important first step in leveling the playing field for homeowners and insurers so they both see the same information. “Suppressing information doesn’t make the underlying risk disappear.”

Top Photo: A view of the flooded area after the severe thunderstorm in Connecticut, United States on June 30, 2024.