A slope tells you the most right after a storm. Water is still moving. Mud lines are fresh. Cracks haven’t had time to dry shut. Give it a week and a lot of that evidence is gone.
So if you own a hillside lot in Poway, the day after heavy rain is the day to walk it. Not during the storm. After. Here’s a simple route, top to bottom, and what each stop is telling you. Our hillside foundation repair page covers repairs. This is about looking.
First, safety
- Wait until the rain has stopped and the ground isn’t actively moving.
- Stay off steep, saturated slope faces. Look from the top, the bottom, or the side.
- Don’t stand below a wall that is leaning, bulging, or dropping soil.
- Stay away from downed lines and fast water in channels.
- If you see a crack opening in the ground near the house, or a door that suddenly won’t close, call for help before you go poking.
Why water is the trigger to watch
Poway’s own Public Safety Element is blunt about it. Among the factors it lists that are likely to start ground movement on unstable slopes is saturation of weak material by prolonged rainfall, over-irrigation, leaky swimming pools or utility pipes, and leach line discharge. Oversteepened slopes, undercut toes, and extra weight on top are on the same list.
You can’t control the rain. You can control where it goes once it lands on your lot. That’s the point of this walk.
Stop 1: the roof and gutters
Start at the house. Look at gutters for overflow marks and sagging runs. Check that every downspout is attached and discharging where it should. A downspout dumping onto the top of a slope sends a concentrated stream right where you don’t want it.
Stop 2: the pad around the house
Walk the perimeter of the foundation.
- Is water ponding against the wall anywhere?
- Did splash or runoff wash soil away from the footing?
- Is the ground still sloping away from the house? The residential code asks for at least six inches of fall in the first ten feet, or drains and swales where the lot can’t do that.
- Are area drains and inlets clear, or packed with mulch and leaves?
Mark any puddles with a stake or a photo. Puddles that are still there a day later are telling you about grading. Our post on DG pads and drainage covers that in more depth.
Stop 3: brow ditches and swales
Many graded slopes have a concrete brow ditch along the top and terrace drains across the face. The City’s Winter Storms page says private owners are responsible for maintaining the drainage courses, storm drains, and creeks on their own property or easement, and it specifically calls out clearing private drainage channels and brow ditches of landscape material and debris.
After a storm, look for:
- Debris dams where leaves, mulch, or rocks stopped the flow.
- Overtopping marks where water jumped the ditch and ran down the slope face.
- Cracks or separated joints in the concrete.
- Undermining, where water has washed out soil beneath the ditch.
An overtopped brow ditch is one of the most common reasons a slope face starts to erode.
Stop 4: the slope face
From a safe spot, scan the slope.
- Rills and gullies. Small channels cut by running water. Note where they start. That’s usually where the water came from.
- Bare patches. Areas where ground cover washed away. The City suggests vegetation or mulch to prevent erosion and, in an emergency, plastic sheeting secured with sandbags over disturbed soil.
- Bulges or slumps. A section of slope that looks pushed out or dropped down. That’s more than erosion.
- Ground cracks. Especially cracks running parallel to the top of the slope. Photograph them with something for scale.
- Wet spots that persist. Seepage coming out of the face days after rain can point to a leak or to water moving through the soil.
Stop 5: retaining walls
Walk the length of every wall.
- Are the weep holes or drains at the base running clear, or plugged?
- Is the wall leaning out compared to your last photos?
- Are there new cracks, or old ones that opened wider?
- Is soil spilling over the top, or washing out at the base?
A wall that can’t drain builds up water pressure behind it. Our post on estate retaining walls in Poway covers the long walls common on bigger lots.
Stop 6: back inside
Finish where you started. Check doors and windows on the downhill side of the house. Look for new cracks in drywall, tile, or slab. If something changed overnight, write the time down.
Do and don’t after the storm
Do:
- Clear brow ditches, inlets, and area drains once it’s safe. The County’s private drainage guide suggests inspecting and cleaning private drains before the rainy season and after storms.
- Redirect downspouts away from the top of slopes.
- Cover fresh bare soil with sheeting and sandbags. When heavy rain is forecast, the City offers free, unfilled sandbags and sand at set locations.
- Shut off irrigation on the slope until it dries out.
- Take dated photos from the same spots every time.
Don’t:
- Don’t push dirt back into a gully and walk away. You’ll be doing it again next storm.
- Don’t regrade or cut into the slope on your own. The City’s grading page says a permit is required for things like excavations two feet or deeper with slopes steeper than 2:1, moving 50 cubic yards or more, or changing drainage patterns. Its small-landscaping exemption has limits too, including staying ten feet from structures and not altering drainage as it leaves or enters neighboring lots.
- Don’t stack new fill or heavy items at the top of a slope.
- Don’t ignore a wall that leans more after every storm.
When to call someone
Erosion you can fix with cleanup and ground cover is one thing. A slump, a ground crack near the house, a wall that moved, or new cracks inside the house are another. The residential code treats footings on or next to slopes steeper than one unit vertical in three horizontal as a special case for setbacks, which is a clue to how sensitive these sites are.
That’s when to get a structural evaluation. On slope and wall problems, coordinate with licensed engineers as needed, because the answer often involves soils and drainage as much as concrete.
What usually shapes the repair scope:
- Erosion only, or actual ground movement.
- Condition of brow ditches, terrace drains, and outlets.
- Wall height, type, and drainage.
- How close the house footings sit to the top of the slope.
- Whether the soil involved is granitic material or clay-bearing fill.
- What permits the City requires for grading and wall work.
We cover all of Poway, from the valley floor to the steepest lots off the hillside roads. If the last storm left you with questions, request a Free Quote. Bring your photos.