FEMA expects more hazard damage per building in Lake San Marcos than in 85% of U.S. towns, mostly from river and rain flooding
On FEMA’s National Risk Index, Lake San Marcos gets a C− for hazard risk: higher expected damage per building than 85% of U.S. towns, #225 of 847 in California. Most of that expected damage is river and rain flooding (85%), then earthquakes (12%). FEMA’s files show no paid flood insurance claims here.
Graded on FEMA’s expected yearly building damage per dollar of building value (NRI v1.20, December 2025), weighted by where residents live; flood claims are shown, not graded. How hazard risk is graded
What Lake San Marcos faces
Each hazard’s share of the building damage FEMA expects here, and how its rate compares with the rest of the country.
River and rain flooding
Earthquakes
Shares are of FEMA’s expected building damage, the measure the grade uses; ranks compare each hazard’s building-damage rate with all 85,154 U.S. census tracts. In FEMA’s terms, river and rain flooding is FEMA’s “Inland Flooding” (rivers and streams overflowing their banks, or rain overwhelming drainage). FEMA defines coastal flooding as high or rising tides and storm surge, so surge damage is counted there. Drought isn’t listed: FEMA counts its losses in crops only.
What’s behind Lake San Marcos’ grade
River and rain flooding is 85% of the building damage FEMA expects in Lake San Marcos, and Lake San Marcos’ rate of river and rain flooding damage is in the top 9% of U.S. census tracts. Wildfire adds 2%, at a rate in the top 8% of U.S. census tracts.
C− #225 of 847 in California; higher expected damage per building than 85% of U.S. towns (21,298).
Lake San Marcos’ residents live in 5 census tracts; FEMA’s figures are combined by where they live.
The typical California town has higher expected damage than 92% of U.S. towns; within the state, Lake San Marcos has less expected damage per building than 74% of California towns.
In dollars, FEMA expects about $2.9M a year in losses across Lake San Marcos: $2.8M to buildings, the rest to people and crops.
Does Lake San Marcos flood? No paid flood claims on record
FEMA’s records show no paid flood insurance claims in Lake San Marcos. That’s not a promise: most homes don’t carry flood insurance, so small floods go unrecorded.
Lake San Marcos isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.
Insurance rates: San Diego County.The storms Lake San Marcos remembers
None of the 30 disasters declared for San Diego County shows FEMA aid or repair money reaching Lake San Marcos itself in FEMA’s records, so these are its biggest flood-claim years.
San Diego County has had 30 natural disasters declared by the President since 1953, most often severe storms, then floods. Not counted: the 2005 Hurricane Katrina evacuee emergency, which covered counties that took in evacuees.
Also 18 FEMA wildfire suppression grants (Fire Management Assistance, not a disaster declaration) for fires in San Diego County, 2002–2018.
Lake San Marcos and its neighbors
Lake San Marcos is 3rd of the 3 graded towns here, from least expected damage per building to most. Tap a town to see its hazards.
| Town | Hazard risk | Mostly (buildings) | Flood claims |
|---|---|---|---|
| Carlsbad | Cmore damage than 66% | river and rain flooding | 14 |
| San Marcos | Cmore damage than 74% | river and rain flooding | 18 |
| Lake San Marcos | C−more damage than 85% | river and rain flooding | 0 |
Hazard risk = FEMA’s expected yearly building damage per dollar of building value, vs. the 21,298 U.S. towns we grade; the map is shaded by fifths of the same scale. Flood claims = paid federal flood insurance claims on record.
Get ready for what Lake San Marcos faces
A short kit for the hazards that drive the building damage here, what to check before you buy, and where neighbors get alerts.
- Turn around at flooded roads: a foot of moving water can carry off a car.
- Flood insurance usually takes 30 days to start, so buy it before the forecast.
- Keep papers and medicines up high, in a grab-and-go bag.
- Drop, cover and hold on.
- Strap tall furniture and the water heater to the wall.
- Know how to shut off the gas.
- Look up the address on FEMA’s flood map.
- Ask the seller or landlord whether it has ever flooded, and what flood insurance costs there.
- Get a flood insurance quote early: policies usually start 30 days after you buy.
Know where neighbors sign up for alerts? Add it to the Handbook so everyone has it.
Questions about natural hazards in Lake San Marcos
Is Lake San Marcos at risk for natural disasters?
On FEMA’s National Risk Index, Lake San Marcos has higher expected damage per building than 85% of U.S. towns: C− for hazard risk, #225 of 847 in California. Most of the expected damage is river and rain flooding (85%) and earthquakes (12%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Is Lake San Marcos in a flood zone?
Flood zones are drawn street by street, so the answer depends on the address: look it up on FEMA’s flood map. In San Diego County, 24% of homes in mapped flood zones carry federal flood insurance, and 0.7% of all homes do.
How much is flood insurance in Lake San Marcos?
FEMA’s Community Rating System list shows no discount for Lake San Marcos’ flood program. Premiums depend on the building; policies usually start 30 days after you buy, so get a quote early.
Is Lake San Marcos at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (85%), and Lake San Marcos’ rate for it is in the top 9% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Lake San Marcos.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Lake San Marcos’ residents lived in the 2020 census; OpenFEMA: NFIP redacted claims, multiple-loss properties, community status book and residential penetration rates, housing assistance (owners and renters), public assistance funded projects, hazard mitigation properties and disaster declarations. Homes: Census ACS 2020–24. Preparedness tips: Ready.gov. FEMA’s model is an average of expected damage, not a forecast. How hazard risk is graded.