People ask us the same thing a lot: “Is my lot in a landslide area?” Fair question. Poway is hilly. The honest answer starts with another question. Which map?
There are several public maps that touch on landslides and slope stability in Poway. They were made by different agencies, at different scales, for different purposes. Used right, they tell you where to look harder. Used wrong, they either scare you for no reason or give you false comfort.
Here’s the straight rundown.
First, what the City says
Start with Poway’s own General Plan. The Public Safety Element, adopted in May 2026, names landslides, rockfalls, seismically induced movement, settlement and expansive soils as the principal geologic hazards in the City.
It also says where landslides tend to come from. Historically, the Friars and Mission Valley formations have been involved in numerous landslides, mostly rotational slides. The element estimates most of them happened 15,000 to 20,000 years ago, and says sliding generally appears to have started at the contact between the upper Friars formation and the lower Stadium Conglomerate. In the granitic terrain, the concern is rockfall from oversteepened slopes.
The element includes a geologic formations map, Figure 6-1. That’s your first look at what kind of ground your neighborhood sits on.
The County’s 2023 hazard mitigation annex for Poway rates landslide as a Medium hazard with limited extent. Translation: it’s real, it’s local, and it isn’t everywhere.
Map one: the CGS landslide hazard maps
The California Geological Survey mapped landslide hazards for the northern San Diego metropolitan area in the mid-1990s. Its San Diego County publication list includes Open-File Report 95-04, Landslide Hazards in the Northern Part of the San Diego Metropolitan Area, published as Landslide Hazard Identification Map No. 35 at 1:24,000 scale. The CGS regional geologic map pamphlet lists Tan and Giffen’s 1995 work among its sources for the Poway quadrangle.
What it’s good for: showing where mapped landslide features and slope-stability problem areas were identified when it was made.
What it isn’t: a parcel survey. At 1:24,000, a pencil line on the map covers a lot of ground. And it reflects what was known when it was drawn.
Map two: the statewide susceptibility map
CGS Map Sheet 58, from 2011, shows susceptibility to deep-seated landslides across California. CGS says it’s based on regional estimates of rock strength and slope steepness, plus the locations of past landslides. Weak rock and steep slopes rate higher.
What it’s good for: a broad sense of whether your part of Poway is in a high- or low-susceptibility setting.
What it isn’t: anything close to lot-level. It’s statewide. The map sheet also notes it doesn’t cover debris flows, the fast, wet slides that follow intense rain, especially after fire.
Map three: the landslide inventory
CGS lists a California Landslide Inventory web application and an Information Warehouse of landslide maps and reports on its maps page. The inventory shows mapped landslide features. The warehouse lets you find and download older CGS landslide maps as PDFs.
What it’s good for: checking whether a mapped landslide feature sits on or near your lot or the slope above it.
What it isn’t: complete. CGS describes its landslide mapping as episodic, often driven by specific disasters and mandates. No mapped feature doesn’t mean no landslide.
Map four: EQ Zapp
CGS’s EQ Zapp tool lets you look up an address against the State’s official earthquake hazard zones. Those zones cover three kinds of ground failure: fault rupture, liquefaction and earthquake-induced landslides. CGS says these zones trigger geologic and engineering investigations for certain projects.
What it’s good for: knowing whether an official zone applies, which matters for building and for disclosure when you sell.
What it isn’t: a general landslide map. It’s about earthquake-induced ground failure where zones have been issued. The Safety Element points out a major earthquake could trigger an old landslide to move again, which is exactly why those zones exist where they do.
Map five: your own parcel’s records
This is the one people skip. It’s often the most useful.
The City of Poway’s records page links to PowGIS, which provides parcel property reports along with engineering, grading and landscape plans, and to a property history search for permits and projects. If your lot was graded as part of a subdivision, there may be grading plans and soils reports on file. Our post on reading a Poway as-graded report explains what to look for when you find one.
A grading file can tell you things no regional map can: whether your pad is cut or fill, how deep the fill is, whether a known slide was removed or buttressed during grading, and what the geologist saw at the time.
How to use them together
Here’s a simple order:
- Look at the Safety Element’s geology map. Is your neighborhood on Friars or Mission Valley formations, granitic rock, or alluvium?
- Check the CGS inventory and older hazard maps for mapped features on or above your lot.
- Run your address in EQ Zapp.
- Pull your parcel’s grading and permit history through the City.
- Then walk the lot. Our after-rain slope walk post lays out what to look for.
If the maps and the ground agree that things are quiet, good. If any of them raise a flag, or the ground shows something the maps don’t, that’s when it stops being a map question.
What the maps can’t tell you
The Safety Element lists what actually sets slopes moving: oversteepening by erosion or grading, especially on slopes over 30 percent; undercutting the base; overloading the slope; saturation from long rains, over-irrigation, leaky pools or pipes and leach line discharge; and earthquake shaking.
None of those show up on a map. They’re about what’s happening on your lot now. A slope that’s been stable for decades can change when someone adds a pool above it or lets a sprinkler run downhill all summer.
Do this
- Read the maps for context, not verdicts.
- Pull your grading file before you buy, build or add onto a hillside lot.
- Keep water off slopes: roof drains, irrigation, pool overflows.
- Note cracks, bulges, leaning walls and fences, and seepage at the toe of a slope.
Don’t do this
- Don’t assume no mapped feature means no risk.
- Don’t assume a mapped feature means your house is moving.
- Don’t regrade, add fill or build near a slope edge without asking what permits and reports apply.
- Don’t rely on a statewide map for a lot-level decision.
When it becomes a geotechnical question
If maps or field signs point toward slope movement, the next step is a site-specific look. The Safety Element says the most effective way to avoid landslide damage is not to develop landslide-prone areas, and that modern engineering can stabilize slide-prone ground through measures like removing or compacting unstable earth, drainage, buttress fills and careful landscaping and irrigation. Those are engineering decisions made from site data. We coordinate with licensed engineers as needed, including geotechnical engineers and engineering geologists.
What drives the scope of that work: how steep and high the slope is, what’s on file for the parcel, whether there’s fill and how deep, how close the house sits to the slope, drainage conditions, access, and what testing is needed. Our hillside foundation repair and fill settlement repair pages explain the foundation side.
We serve all of Poway. If the maps have you wondering, or the slope has you worried, send a Free Quote request and we’ll help you sort out which question you’re really asking.