1,784 flood insurance claims·$49.6M paid·6 federal flood & hurricane disasters
Share of the whole county outline, rivers and lakes included; parts FEMA hasn’t mapped count as zero.
Shaded areas are FEMA’s mapped flood hazard zones in and around Boulder County, Colorado. Zoomed out they are simplified; at street level the map switches to FEMA’s exact layer. Tap anywhere to check that spot, or search an address above.
Flash flooding from summer thunderstorms dominates the flood risk profile in Boulder County, CO, backed by 31 recorded flash flood events and 4 deaths compared to 6 standard flood events over the last 30 years.
Recent history illustrates this hazard. In June 2015, severe thunderstorms produced minor flooding and mudslides along the Saint Vrain River and south of Bohn Park in Lyons. Later, a June 2021 thunderstorm triggered a 3 to 4 foot surge of debris and water flowing down Geer Canyon in the Calwood burn area, impacting Geer Canyon Drive. Another flash flood event occurred in July 2021, when up to 2.5 inches of rain fell in the Calwood and Cameron Peak burn areas, and 3.5 to 4.5 inches of rain produced flash flooding and stranded vehicles in Erie.
Homeowners and real estate agents should pay the most attention to properties in Zone A, which accounts for 888 NFIP claims with an average payout of $45,651 and an average recorded water depth of 8 inches, as well as Zone X properties, which logged 791 claims with an average payout of $26,441 and an average recorded water depth of 7 inches.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
10% of Boulder County’s flood insurance claims were on properties rated outside FEMA’s high-risk zones.
985 NFIP claims with a recorded rated flood zone, 1978 to date. The zone is the one FEMA used to rate that policy, which may not match today’s map. Source: OpenFEMA NFIP claims.
In flood insurance claims here that reported a flood depth, the average was 8 inches.
Drawn to scale against an 80-inch door. Even a few inches soaks flooring, the bottom of the drywall and anything plugged in near the floor.
Average of the depths reported on claims (zero and implausible values left out); FEMA’s record doesn’t say exactly where each depth was measured. Source: OpenFEMA NFIP claims.
The worst year was 2013, with 1,520 claims and $48.4M paid, the year of Severe Storms, Flooding, Landslides, and Mudslides.
Bar height is scaled by square root so ordinary years stay visible next to the worst one. NFIP claims by year of loss. Source: OpenFEMA.
13 NOAA storm reports from Boulder County describe what happened, in the words of the forecasters who covered it. Read the Colorado flood stories →
19 federal disaster declarations since 1969, 6 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Stone Mountain Fire | Jul 30, 2024 |
| Marshall Fire | Dec 30, 2021 |
| Wildfires And Straight-line Winds | Dec 30, 2021 |
| Calwood Fire | Oct 17, 2020 |
| Severe Storms, Tornadoes, Flooding, Landslides, And Mudslides | May 4, 2015 |
| Severe Storms, Flooding, Landslides, And Mudslides | Sep 11, 2013 |
| Four Mile Canyon Fire | Sep 6, 2010 |
| Olde Stage Fire | Jan 7, 2009 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
37 since 1996: 31 flash floods and 6 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flash Flood | Jul 31, 2021 | $10,000 |
| Flash Flood | Jul 30, 2021 | $20,000 |
| Flash Flood | Jun 27, 2021 | $10,000 |
| Flood | May 8, 2015 | $100,000 |
| Flash Flood | Jun 4, 2015 | $15,000 |
| Flash Flood | Sep 12, 2013 | — |
| Flood | Sep 12, 2013 | — |
| Flood | Sep 12, 2013 | $297.0M |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flash Flood · Jul 31, 2021. Heavy rain in the Calwood burn areas caused flash flooding from Geer Canyon Drive to CO 36.
Flash Flood · Jul 30, 2021. Flash flooding occurred on Tonahutu Creek. Trees, mud and debris shut down Grand Lake's hydro plant. Approximately 50 downed trees piled up at the plant's head gate and ash and mud filled the ditch leading to another gate. Another flash flood impacted CO-125. Additional flash flooding occurred in the Calwood and Cameron Peak burn areas, where up to 2.5 inches of rain fell in one hour. In Erie, heavy rain anyw…
Flash Flood · Jun 27, 2021. A thunderstorm produced heavy rain and flash flooding in the Calwood burn area. Law enforcement reported a 3 to 4 foot surge of debris and water flowing down Geer Canyon. |The debris flow impacted stretches of Geer Canyon Drive and the lower part of Geer Canyon.
Flood · May 8, 2015. Areal flooding developed along the Cache La Poudre and South Platte River Basins as a combination of heavy rainfall and spring runoff unundated the region. The Cache La Poudre reached flood stage from the 10th the the 14th. The South Platte rose above flood stage at Kersey from the 9th to the 15th. A few landslides were initially reported along the Saint Vrain River with minor flooding south of Bohn Park in Lyo…
National Weather Service narratives, lightly trimmed. Source: NOAA Storm Events Database.
Every colour on the map above is a place on this drawing: where the ground sits relative to the flood FEMA plans for.
If a building in Boulder County is in a high-risk zone (A or V) and its mortgage comes from a federally regulated or insured lender, or is federally backed, flood insurance is required.
Outside those zones it is optional, and often worth having: from 2014 to 2024 nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area. Since Risk Rating 2.0, NFIP premiums are set for each building, so the only reliable price is a quote: FloodSmart.gov or a local agent.