Williamson County flood history
Illinois · From FEMA's flood insurance and disaster data · Updated 2026-10-08
FEMA's National Flood Insurance Program (NFIP) data lists 239 flood insurance claims in Williamson County, Illinois since 1978. The NFIP paid $2.1 million on them (building, contents and Increased Cost of Compliance payments, in the dollars of the year paid).
The year with the most claims was 1996, with 38.
In the last ten years (2017–2026) there were 29 claims, and the average paid claim was $19,575.
21% of the claims with a recorded flood zone came from buildings outside FEMA's high-risk zones (rated zones B, C and X).
About 0.5% of homes in Williamson County, Illinois had an NFIP flood policy in FEMA's latest count (141 of 29,524 residential buildings). In the high-risk flood zones (Special Flood Hazard Areas), it was 15% (106 of 715).
Since 2000, FEMA has made 3 flood-related disaster declarations covering Williamson County, Illinois. The most recent was DR-1991-IL (Severe Storms and Flooding), declared June 7, 2011.
NFIP claims by year
Show as a table
| Year | Claims | Paid |
|---|---|---|
| 2026 | 3 | $0 |
| 2023 | 3 | $59,086 |
| 2022 | 1 | $0 |
| 2021 | 1 | $3,863 |
| 2018 | 1 | $1,944 |
| 2017 | 20 | $326,612 |
| 2011 | 6 | $8,174 |
| 2010 | 2 | $22,983 |
| 2009 | 6 | $68,300 |
| 2008 | 33 | $382,464 |
| 2005 | 3 | $7,299 |
| 2002 | 1 | $147 |
| 2000 | 2 | $0 |
| 1999 | 6 | $53,724 |
| 1998 | 4 | $28,998 |
| 1997 | 1 | $499 |
| 1996 | 38 | $467,820 |
| 1993 | 6 | $63,618 |
| 1991 | 9 | $113,265 |
| 1990 | 10 | $135,783 |
| 1989 | 4 | $132 |
| 1985 | 6 | $20,614 |
| 1984 | 10 | $78,741 |
| 1983 | 25 | $119,771 |
| 1982 | 34 | $136,797 |
| 1980 | 1 | $0 |
| 1979 | 2 | $5,207 |
| 1978 | 1 | $186 |
Named flood events
| Event | Year | Claims | Paid |
|---|---|---|---|
| March storm | 2008 | 24 | $357,667 |
| Flooding | 1982 | 6 | $10,608 |
| Mid-spring storms | 2011 | 6 | $8,174 |
| Flooding | 1985 | 1 | $2,801 |
How many homes have flood insurance
FEMA counts 141 residential NFIP policies in Williamson County, against 29,524 residential buildings (0.5%). Of the 715 residential buildings in high-risk flood zones (Special Flood Hazard Areas), 106 have an NFIP policy (15%). Private flood policies aren't in these counts.
Whether you're required to carry flood insurance depends on your flood zone and your mortgage. See do I need flood insurance?
Flood-related disaster declarations
| Declaration | Declared | Event | Help for individuals |
|---|---|---|---|
| DR-1991-IL | Jun 7, 2011 | Severe Storms and Flooding | Yes |
| DR-1850-IL | Jul 2, 2009 | Severe Storms, Flooding, and Tornadoes | No |
| DR-1416-IL | May 21, 2002 | Severe Storms, Tornadoes and Flooding | Yes |
Check your own address
County numbers can't tell you about a single building. Look up your property on FEMA's flood map, then read what your flood zone means. More counties: all of Illinois.
Where these numbers come from
All figures on this page are calculated from FEMA's public OpenFEMA datasets:
- NFIP Redacted Claims (v3) (FEMA (OpenFEMA)): NFIP claims since 1978, downloaded 2026-10-08. Dollar amounts are what the NFIP paid, not adjusted for inflation. Claims filed under private flood insurance aren't included.
- NFIP Residential Penetration Rates (v1) (FEMA (OpenFEMA)): NFIP residential policy contracts in force (as of August 3, 2026) divided by FEMA's count of residential buildings from the National Structure Inventory. FEMA notes that inventory is incomplete in some counties, which can inflate the rate. Private flood policies aren't counted.
- Disaster Declarations Summaries (v2) (FEMA (OpenFEMA)): disaster declarations, downloaded 2026-10-08. We count a declaration as flood-related when FEMA lists flooding (or a dam or levee break) as its incident type or a designated incident type, or the declaration's title mentions flooding.
FEMA's redacted claims data doesn't identify properties, and FEMA notes that some records lack a county or flood zone. See how we use the data.